Biomolecules Class 12 Chemistry Chapter 10 Notes

Biomolecules Class 12 Chemistry Chapter 10 Notes

Carbohydrates

• Carbohydrates are vital organic compounds primarily synthesized by plants.
• They form a diverse and extensive group of naturally occurring substances.

Common Carbohydrates

• Examples of carbohydrates include cane sugar, glucose, and starch.
• They exhibit a general chemical formula: Cx(H2O)y, which led to their name, “carbohydrates,” indicating they are hydrates of carbon.

General Formula and Exceptions

• The general formula Cx(H2O)y is characteristic of carbohydrates, e.g., glucose (C6H12O6) fits as C6(H2O)6.
• However, not all compounds conforming to this formula are considered carbohydrates.
• For instance, acetic acid (CH3COOH) fits C2(H2O)2 but isn’t categorized as a carbohydrate.
• Conversely, rhamnose (C6H12O5) is a carbohydrate but doesn’t adhere strictly to this definition.

Chemical Definition

• Carbohydrates are chemically defined as optically active polyhydroxy aldehydes or ketones or compounds that yield such units upon hydrolysis.
• This broad definition accommodates the structural diversity within carbohydrates.

Sweet Carbohydrates and Sugars

• Some carbohydrates are sweet-tasting and referred to as sugars.
• Common sugars include sucrose (table sugar) and lactose (milk sugar).
• Sucrose, composed of glucose and fructose molecules, is widely used in homes.
• Lactose is found in milk.

Alternate Name: Saccharides

• Carbohydrates are also known as saccharides, derived from the Greek word “sakcharon,” meaning sugar.

Functional Groups

• Carbohydrates exhibit specific functional groups, contributing to their reactivity and roles in biological processes.
• The hydroxyl (-OH) groups and carbonyl (C=O) groups are common functional motifs in carbohydrates.

Biological Significance

• Carbohydrates serve crucial roles in living organisms, such as:
  • Energy sources: They are a primary source of metabolic energy.
  • Structural components: Carbohydrates form structural elements in cells (e.g., cellulose in plant cell walls).
  • Recognition and signaling: They participate in cell recognition and signaling processes (e.g., glycoproteins and glycolipids).

Classification: Monosaccharides, Disaccharides, Polysaccharides

• Carbohydrates are categorized into monosaccharides (single sugar units), disaccharides (two sugar units), and polysaccharides (complex carbohydrates composed of many sugar units).

Classification of Carbohydrates

• Carbohydrates are classified based on their behavior during hydrolysis, the process of breaking them down into simpler units.
• They are broadly categorized into three groups: monosaccharides, oligosaccharides, and polysaccharides.

1. Monosaccharides

• Definition: Monosaccharides are carbohydrates that cannot be further hydrolyzed into simpler units. They are the simplest form of carbohydrates.
• Examples: Common monosaccharides include glucose, fructose, and ribose.
• Natural Occurrence: Approximately 20 different monosaccharides are found in nature.

2. Oligosaccharides

• Definition: Oligosaccharides are carbohydrates that yield two to ten monosaccharide units upon hydrolysis.
• Further Classification: Depending on the number of monosaccharides produced upon hydrolysis, oligosaccharides can be classified as disaccharides (two units), trisaccharides (three units), tetrasaccharides (four units), and so on.
• Common Type: Disaccharides are the most common type of oligosaccharides.
• Example: Sucrose, when hydrolyzed, yields one molecule of glucose and one molecule of fructose. Maltose produces two molecules of glucose upon hydrolysis.

3. Polysaccharides

• Definition: Polysaccharides are carbohydrates that yield a large number of monosaccharide units upon hydrolysis.
• Examples: Common polysaccharides include starch, cellulose, glycogen, and various gums.
• Sweetness: Polysaccharides are not sweet in taste and are also referred to as non-sugars.
• Biological Roles: They serve as energy storage (e.g., glycogen) and structural components (e.g., cellulose) in organisms.

Additional Classification: Reducing and Non-Reducing Sugars

• Reducing Sugars: Carbohydrates that can reduce Fehling’s solution and Tollens’ reagent are classified as reducing sugars.
• Characteristics: Monosaccharides, whether aldose or ketose, are examples of reducing sugars.
• Explanation: Reducing sugars have free aldehyde or ketone functional groups, which can participate in chemical reactions, including reduction.

Monosaccharides

• Monosaccharides are the simplest form of carbohydrates, consisting of a single sugar unit.
• They are further classified based on the number of carbon atoms and the type of functional group present.

1. Classification by Carbon Atoms

• Monosaccharides are categorized by the number of carbon atoms in their molecular structure.
• The most common categories include:
  • Trioses: Monosaccharides with three carbon atoms (e.g., glyceraldehyde).
  • Tetroses: Monosaccharides with four carbon atoms (e.g., erythrose).
  • Pentoses: Monosaccharides with five carbon atoms (e.g., ribose).
  • Hexoses: Monosaccharides with six carbon atoms (e.g., glucose).
  • Heptoses: Monosaccharides with seven carbon atoms (e.g., sedoheptulose).
• The number of carbon atoms influences the properties and functions of the monosaccharide.

2. Classification by Functional Groups

• Monosaccharides are also classified based on the type of functional group they contain:
  • Aldose: Monosaccharides that contain an aldehyde functional group (e.g., glucose, which is an aldohexose).
  • Ketose: Monosaccharides that contain a ketone functional group (e.g., fructose, which is a ketohexose).
• The presence of either an aldehyde or a ketone group distinguishes aldoses from ketoses.

Significance of Classification

• The classification of monosaccharides by carbon atoms and functional groups is crucial in understanding their structure, reactivity, and biological roles.
• It helps distinguish between different monosaccharides and predict their behavior in chemical reactions and metabolic pathways.

Glucose

• Glucose is a fundamental monosaccharide, known as a simple sugar, and is a key source of energy for living organisms.
• It is found both freely in nature and in various combined forms.

Occurrence of Glucose in Nature

• Free Form: Glucose occurs freely in nature, particularly in sweet-tasting substances.
• Sweet Fruits: It is naturally present in sweet fruits, contributing to their sweet taste. Examples include apples, bananas, and oranges.
• Honey: Glucose is a major component of honey, giving it its characteristic sweetness.
• Ripe Grapes: Ripe grapes contain significant amounts of glucose, which contributes to the sweetness of grapes and is important in winemaking.

Combined Forms

• Glucose can also be found in various combined forms within complex carbohydrates like starch and cellulose.
• Starch: It is a storage polysaccharide in plants, composed of glucose molecules linked together. Sources of dietary starch include potatoes and grains.
• Cellulose: Another polysaccharide, cellulose, found in plant cell walls, is made up of glucose units. Although indigestible by humans, cellulose is a vital component of dietary fiber.

Biological Significance

• Glucose serves as a primary source of energy in cellular respiration.
• It plays a crucial role in metabolic processes, including glycolysis and the citric acid cycle.
• Blood glucose levels are tightly regulated in the human body to ensure a constant supply of energy to cells.

Preparation of Glucose

1. Production of Glucose from Sucrose (Cane Sugar):

• Sucrose (C12H22O11), commonly known as cane sugar, can be hydrolyzed to yield equal amounts of glucose and fructose when treated with dilute acids in an alcoholic solution. The reaction can be represented as follows:
  • Reaction: Sucrose (C12H22O11) + H2O + Acid (e.g., HCl or H2SO4) → Glucose (C6H12O6) + Fructose (C6H12O6)
  • This process breaks the glycosidic bond between glucose and fructose in sucrose, resulting in the formation of the two monosaccharides, glucose and fructose, in equal quantities.
  • The reaction takes place under controlled conditions, often involving dilute acids and alcohol as a solvent.

2. Production of Glucose from Starch (or Cellulose):

• Commercial production of glucose involves the hydrolysis of starch, a polysaccharide, through a process that uses dilute sulfuric acid (H2SO4). The reaction is typically carried out under elevated temperature and pressure.
  • Reaction: (C6H10O5)n (Starch or Cellulose) + nH2O + H2SO4 → nC6H12O6 (Glucose)
  • In this reaction, starch (or cellulose), which is a polymer of glucose molecules, is broken down into individual glucose units.
  • The process is conducted at a temperature of 393 K (approximately 120°C) and a pressure of 2-3 atmospheres.
  • The resulting product is a solution containing glucose.

Significance:

• The production of glucose from sucrose and starch is essential in various industries, including the food and pharmaceutical sectors.
• Glucose is a crucial source of energy and a precursor for the synthesis of other compounds, making it valuable in both industrial and biological applications.
• These hydrolysis processes enable the efficient conversion of complex carbohydrates into simpler, more readily usable forms of sugar.

Structure of Glucose

• Glucose, also known as dextrose, is a fundamental monosaccharide with critical roles in biology and is a building block for larger carbohydrates like starch and cellulose.
• Its molecular structure and configuration were determined through a series of chemical reactions and comparisons with known compounds, specifically glyceraldehyde.

Key Evidences and Structural Determination of Glucose:

1. Molecular Formula: Glucose’s molecular formula, C6H12O6, was established through chemical analysis.

2. Chain Structure: When subjected to prolonged heating with HI, glucose forms n-hexane, indicating that all six carbon atoms are linked in a straight chain.

3. Carbonyl Group: Glucose reacts with hydroxylamine to form an oxime and adds hydrogen cyanide to form a cyanohydrin. These reactions confirm the presence of a carbonyl group (>C=O) in glucose.

4. Aldehydic Group: Glucose can be oxidized by a mild oxidizing agent like bromine water to form a six-carbon carboxylic acid called gluconic acid, indicating the presence of an aldehydic group.

5. Five Hydroxyl Groups: Acetylation of glucose with acetic anhydride results in glucose pentaacetate, confirming the presence of five -OH groups. This implies that these -OH groups are attached to different carbon atoms.

6. Primary Alcoholic Group: When oxidized with nitric acid, both glucose and gluconic acid yield saccharic acid, indicating the presence of a primary alcoholic (-OH) group in glucose.

Configuration of Glucose:

• Emil Fischer determined the exact spatial arrangement of different -OH groups in glucose, leading to the Fischer projection.
• Glucose’s configuration is represented as D(+)-glucose, where ‘D’ indicates the configuration, and ‘(+)’ denotes its dextrorotatory nature. It’s important to note that ‘D’ and ‘L’ configurations are not related to optical activity.
• The ‘D’ configuration in glucose means that it has a configuration similar to the (+) isomer of glyceraldehyde, where the -OH group is on the right side in the structural formula.
• The lowest asymmetric carbon atom in glucose, marked in the structure, is compared to glyceraldehyde for configuration assignment.
• Glucose’s structure is written so that the most oxidized carbon (-CHO) is at the top.

Cyclic Structure of Glucose

• Glucose’s cyclic structure was proposed to explain certain reactions and properties that couldn’t be accounted for by its open-chain structure.
• The formation of a six-membered ring involving the -OH group at C-5 was proposed, leading to the existence of two cyclic forms, known as anomers.

Cyclic Hemiacetal Formation:

• The open-chain structure (I) of glucose was unable to explain certain reactions and facts:
  1. Glucose’s failure to give Schiff’s test and form hydrogensulphite addition products with NaHSO3, despite having an aldehyde group.
  2. The pentaacetate of glucose’s inability to react with hydroxylamine, indicating the absence of a free -CHO group.
  3. The existence of two crystalline forms of glucose (a and b), with different melting points.

Cyclic Hemiacetal Explanation:

• To address these issues, it was proposed that glucose forms a cyclic hemiacetal structure.
• In this structure, one of the -OH groups adds to the -CHO group, forming a six-membered ring.
• The -OH group at C-5 is involved in ring formation, leading to the absence of the -CHO group.
• The two cyclic forms, a and b, are known as anomers and exist in equilibrium with the open-chain structure.

Pyranose Structure:

• The six-membered cyclic structure of glucose is called a pyranose structure, named after pyran, a cyclic organic compound with one oxygen atom and five carbon atoms in the ring.
• The cyclic structure of glucose can be more accurately represented using Haworth structures.

Fructose

• Fructose is a significant monosaccharide known as a ketohexose.
• It is obtained through the hydrolysis of the disaccharide sucrose and is naturally found in various sweet-tasting substances.

Occurrence of Fructose:

• Formation from Sucrose: Fructose is obtained alongside glucose through the hydrolysis of sucrose (a disaccharide), which is commonly found in sugar cane, sugar beets, and many sweet fruits.
• Natural Sources: Fructose is a naturally occurring monosaccharide found in fruits, honey, and certain vegetables.
• Use as a Sweetener: In its pure form, fructose is used as a sweetener due to its high sweetness level. It is often used as an alternative to sucrose and is found in various processed foods and beverages.

Chemical Classification: Ketohexose:

• Fructose is classified as a ketohexose because it contains a ketone functional group and has six carbon atoms in its structure.
• This classification is based on its chemical structure, which differentiates it from aldohexoses like glucose.

Significance of Fructose:

• Fructose plays essential roles in nutrition and food industry:
  • Sweetening Agent: It is used as a natural sweetening agent due to its high sweetness level, making it a desirable alternative to sucrose.
  • Dietary Source: It is a component of many fruits and vegetables, contributing to their sweet taste.
  • Energy Source: Like glucose, fructose serves as an energy source for living organisms when metabolized in the body.
  • Processed Foods: It is used in the food industry to sweeten and enhance the flavor of various products, including beverages, baked goods, and snacks.

Structure of Fructose

• Fructose is a ketohexose monosaccharide with the molecular formula C6H12O6.
• It contains a ketonic functional group at carbon number 2 and exists in both open-chain and cyclic forms.
• Fructose belongs to the D-series and is a laevorotatory compound, meaning it rotates plane-polarized light to the left.
• It is appropriately represented as D-(–)-fructose.

Open-Chain Structure:

• The open-chain structure of fructose is shown below:

   H
   |
C–H
   |
C=O
   |
C–H
   |
C–OH
   |
C–OH
   |
C–OH
   |
C–OH

• In the open-chain structure, fructose is similar to glucose with six carbon atoms in a straight chain.

Cyclic Forms – Furanose Ring:

• Fructose can exist in two cyclic forms, which are obtained by the addition of -OH at C5 to the ketone (C=O) group.
• The ring formed in these structures is a five-membered ring and is named as furanose, drawing an analogy to the compound furan.
• Furan is a cyclic compound with one oxygen atom and four carbon atoms in a five-membered ring.

Haworth Structures:

• The cyclic structures of the two anomers of fructose, which represent its Haworth structures, are as follows:

α-Fructose:

          O
         //
C–H–C
     |
     C–H
     |
     C–OH
     |
     C–OH
     |
     C–OH
     |
     C–OH

β-Fructose:

      O
     //
C–OH–C
     |
     C–H
     |
     C–OH
     |
     C–OH
     |
     C–OH
     |
     C–OH

• The α and β forms represent the two possible anomers of fructose, which exist in an equilibrium.
• The cyclic structures show a five-membered ring, with the oxygen atom bridging two carbon atoms in the ring.

Disaccharides

• Disaccharides are carbohydrates composed of two monosaccharide units joined together by a glycosidic linkage formed through the loss of a water molecule.
• The properties of disaccharides depend on whether the reducing groups of the constituent monosaccharides are involved in glycosidic bond formation.
• This note discusses three common disaccharides: sucrose, maltose, and lactose.

1. Sucrose:

• Composition: Sucrose is composed of two monosaccharides, D-(+)-glucose and D-(-) fructose.
• Glycosidic Linkage: The glycosidic linkage is formed between C1 of a-D-glucose and C2 of b-D-fructose.
• Reducing Sugar: Sucrose is a non-reducing sugar because the reducing groups of both glucose and fructose are involved in glycosidic bond formation.
• Rotation: Sucrose is dextrorotatory. Upon hydrolysis, it yields dextrorotatory glucose and laevorotatory fructose. This mixture is laevorotatory, and it is called invert sugar because the sign of rotation changes from dextro (+) to laevo (-) during hydrolysis.

2. Maltose:

• Composition: Maltose is composed of two a-D-glucose units.
• Glycosidic Linkage: The glycosidic linkage is formed between C1 of one glucose unit and C4 of another glucose unit.
• Reducing Sugar: Maltose is a reducing sugar because it has a free aldehyde group at C1 of the second glucose unit. This free group shows reducing properties.

3. Lactose:

• Composition: Lactose, also known as milk sugar, is composed of b-D-galactose and b-D-glucose.
• Glycosidic Linkage: The glycosidic linkage is formed between C1 of galactose and C4 of glucose.
• Reducing Sugar: Lactose is a reducing sugar because it can produce a free aldehyde group at C1 of the glucose unit, showing reducing properties.
• Occurrence: Lactose is commonly found in milk.

Polysaccharides

• Polysaccharides are complex carbohydrates composed of numerous monosaccharide units linked together by glycosidic linkages.
• They play crucial roles in both plants and animals, serving as food storage and structural materials.

1. Starch:

• Plant Storage Polysaccharide: Starch is the primary storage polysaccharide in plants, making it a vital dietary source for humans.
• Sources: It is abundant in cereals, roots, tubers, and some vegetables.
• Composition: Starch consists of two components, amylose and amylopectin.
  • Amylose: Amylose is a water-soluble component, constituting about 15-20% of starch. It is a long, unbranched chain composed of a-D-(+)-glucose units linked together by C1–C4 glycosidic linkages.
  • Amylopectin: Amylopectin, comprising 80-85% of starch, is insoluble in water. It is a branched chain polymer of a-D-glucose units. The chain formation occurs via C1–C4 glycosidic linkages, and branching occurs through C1–C6 glycosidic linkages.

2. Cellulose:

• Plant Structural Polysaccharide: Cellulose is exclusively found in plants and is the most abundant organic substance in the plant kingdom.
• Role: It serves as a predominant constituent of the cell walls of plant cells, providing structural support.
• Composition: Cellulose is composed of a straight chain of b-D-glucose units joined by glycosidic linkages between C1 of one glucose unit and C4 of the next glucose unit.

3. Glycogen:

• Animal Storage Polysaccharide: Glycogen is the carbohydrate storage form in animals, often referred to as “animal starch” due to its structural similarity to amylopectin.
• Distribution: It is found in various tissues, including the liver, muscles, and brain, and serves as an energy reserve.
• Structure: Glycogen is highly branched, with a structure similar to amylopectin, but it is more extensively branched.

Importance of Carbohydrates

• Carbohydrates are vital molecules in both plant and animal life, playing numerous essential roles. Their significance extends to various aspects of human existence.

1. Energy Source:

• Carbohydrates are a major source of energy for all living organisms.
• They are rapidly metabolized to produce energy, making them crucial for sustaining life.
• Honey, a carbohydrate-rich substance, has been used as an instant source of energy in traditional medicine systems like Ayurveda.

2. Storage Molecules:

• Carbohydrates serve as storage molecules for energy in both plants and animals.
• In plants, starch acts as a storage form of carbohydrates.
• In animals, glycogen is the primary storage carbohydrate found in tissues like the liver and muscles.

3. Structural Components:

• Cellulose, a carbohydrate, is a key structural component in plant cell walls.
• Wood, which contains cellulose, is used in the construction of furniture.
• Cotton fiber, composed of cellulose, is used for making textiles, clothing, and various fabrics.

4. Industrial Applications:

• Carbohydrates are vital to several industries:
  • Textiles: Carbohydrates, like cellulose, are used in textile manufacturing.
  • Paper: The paper industry relies on cellulose for paper production.
  • Lacquers: Carbohydrates are used in the production of lacquers and coatings.
  • Breweries: Carbohydrates, primarily maltose, are used in the brewing process to produce alcohol.

5. Nucleic Acids:

• Carbohydrates are integral components of nucleic acids:
  • D-ribose and 2-deoxy-D-ribose, both aldopentoses, are present in nucleic acids like DNA and RNA.
  • These sugars play crucial roles in the structure and function of genetic material.

6. Biological Combinations:

• Carbohydrates are often found in combination with proteins and lipids in biological systems.
• These combinations are essential for various cellular processes, including cell signaling and recognition.

Proteins

• Proteins are the most abundant biomolecules in living systems, with critical roles in various physiological processes.
• They are derived from various food sources such as milk, cheese, pulses, peanuts, fish, and meat.
• Proteins are essential components present throughout the body, serving as the building blocks of life and performing vital functions.
• The term “protein” is derived from the Greek word “proteios,” meaning primary or of prime importance.
• All proteins are composed of a-amino acids, making them fundamental to life.

Key Functions of Proteins:

1. Structural Role: Proteins provide structural support to cells and tissues. For example, collagen is a protein that forms the structural framework of skin, tendons, and bones.
2. Enzymatic Activity: Enzymes are specialized proteins that catalyze biochemical reactions in the body. They play a crucial role in metabolism, helping to break down and build up molecules.
3. Transport: Some proteins, like hemoglobin, are responsible for transporting essential molecules such as oxygen and nutrients in the blood.
4. Hormones: Proteins can act as hormones, regulating various physiological processes. For instance, insulin is a protein hormone that controls blood sugar levels.
5. Immune Function: Antibodies, a type of protein, play a vital role in the immune system by recognizing and neutralizing foreign invaders like bacteria and viruses.
6. Muscle Contraction: Proteins like actin and myosin are essential for muscle contraction and movement.
7. Cell Signaling: Signaling proteins relay messages within cells, allowing for coordinated responses to external and internal stimuli.

Structure of Proteins:

• Proteins are polymers made up of a-amino acids, which are linked together by peptide bonds.
• The sequence of amino acids in a protein determines its unique structure and function.
• Proteins have four levels of structural organization: primary, secondary, tertiary, and quaternary, each contributing to their specific functions.

Amino Acids

• Amino acids are organic molecules that serve as the building blocks of proteins.
• They are characterized by the presence of amino (-NH2) and carboxyl (-COOH) functional groups.
• Amino acids are classified based on the relative position of the amino group with respect to the carboxyl group, with a-amino acids being the most common and relevant to protein synthesis.
• These molecules have trivial names often reflecting their properties or sources, and they are commonly represented using three-letter symbols, with one-letter symbols also used for convenience.

Key Characteristics of Amino Acids:

• Amino Group: All amino acids contain an amino (-NH2) group, which is responsible for their basic properties.
• Carboxyl Group: A carboxyl (-COOH) group is present in all amino acids, contributing to their acidic properties.
• Alpha Carbon: A central alpha carbon (α-C) is the key structural feature of amino acids, to which the amino group, carboxyl group, hydrogen atom, and a variable side chain (R group) are attached.
• Chirality: Most amino acids exhibit chirality, existing in two enantiomeric forms (D and L). In proteins, only L-amino acids are commonly found.
• Amino Acid Side Chains: The side chains (R groups) vary among different amino acids, imparting distinct chemical properties to each.

Roles of Amino Acids:

1. Protein Synthesis: Amino acids serve as the building blocks for protein synthesis. They are linked together by peptide bonds to form polypeptide chains.
2. Enzyme Function: Some amino acids are essential components of enzymes, catalyzing biochemical reactions.
3. Neurotransmitters: Amino acids like glutamate and gamma-aminobutyric acid (GABA) function as neurotransmitters in the nervous system.
4. Structural Proteins: Amino acids such as glycine, proline, and hydroxyproline contribute to the structure of proteins like collagen.
5. Energy Source: In times of need, amino acids can be metabolized for energy production.
6. Hormones: Amino acids are involved in the synthesis of various hormones, including insulin.

Classification of Amino Acids

• Amino acids are organic compounds that are categorized as acidic, basic, or neutral based on the relative number of amino (-NH2) and carboxyl (-COOH) groups in their molecular structure.
• They are essential building blocks of proteins and play various roles in biological processes.
• Amino acids are either synthesized within the body (non-essential) or must be obtained through the diet (essential).

Classification of Amino Acids:

1. Neutral Amino Acids:
   • These amino acids have an equal number of amino and carboxyl groups in their structure, making them neutral in overall charge.
   • Examples: Glycine, alanine, valine.
2. Basic Amino Acids:
   • Basic amino acids have more amino (-NH2) groups than carboxyl (-COOH) groups.
   • They are positively charged at physiological pH.
   • Examples: Arginine, lysine, histidine.
3. Acidic Amino Acids:
   • Acidic amino acids possess more carboxyl (-COOH) groups compared to amino (-NH2) groups.
   • They are negatively charged at physiological pH.
   • Examples: Aspartic acid, glutamic acid.

Characteristics of Amino Acids:

• Amino acids are typically colorless, crystalline solids.
• They are water-soluble and have high melting points, behaving more like salts than simple amines or carboxylic acids.
• In aqueous solutions, amino acids can lose a proton from the carboxyl group (-COOH) and accept a proton by the amino group (-NH2), forming a zwitterion.
• A zwitterion is a dipolar ion that is electrically neutral but contains both positive and negative charges.
• Amino acids exhibit amphoteric behavior as they can react with both acids and bases.
• Most naturally occurring a-amino acids are optically active because the α-carbon atom is asymmetric, leading to the existence of both ‘D’ and ‘L’ forms.
• In proteins, the majority of amino acids have the L-configuration, where the -NH2 group is on the left-hand side when represented in structural formulas.

Structure of Proteins

• Proteins are essential biomolecules found in all living organisms, serving various functions in biological processes.
• They are polymers composed of a-amino acids linked together by peptide bonds.
• Protein structures can be classified into four levels: primary, secondary, tertiary, and quaternary, each building upon the previous level of complexity.

1. Primary Structure of Proteins:

• The primary structure of a protein refers to the specific sequence of amino acids in a polypeptide chain.
• Any change in the sequence results in a different protein.
• It is the most basic level of protein structure.

2. Secondary Structure of Proteins:

• Secondary structure describes the regular folding patterns within a polypeptide chain.
• Two common secondary structures are the a-helix and b-pleated sheet:
  • a-Helix: The polypeptide chain forms a right-handed helical structure stabilized by hydrogen bonds between the amino and carboxyl groups of the peptide bonds.
  • b-Pleated Sheet: Peptide chains are stretched out and aligned side by side, forming a sheet-like structure with hydrogen bonds between adjacent chains.
• Hydrogen bonds play a crucial role in stabilizing secondary structures.

3. Tertiary Structure of Proteins:

• Tertiary structure represents the overall 3D folding of the polypeptide chain.
• It is responsible for creating the final shape of the protein.
• Tertiary structure can be fibrous or globular:
  • Fibrous Proteins: Polypeptide chains run parallel and are held together by hydrogen and disulfide bonds. Examples include keratin and myosin.
  • Globular Proteins: Chains fold into a spherical shape and are typically soluble in water. Examples include insulin and albumins.
• Stabilizing forces include hydrogen bonds, disulfide linkages, van der Waals interactions, and electrostatic attractions.

4. Quaternary Structure of Proteins:

• Some proteins are composed of multiple polypeptide chains called subunits.
• Quaternary structure describes the spatial arrangement of these subunits with respect to each other.
• It involves interactions between subunits, such as hydrogen bonds, disulfide bridges, and hydrophobic interactions.
• Not all proteins have quaternary structures; some consist of a single polypeptide chain.

Denaturation of Proteins

• Proteins in their native state possess a unique three-dimensional structure, which is essential for their biological activity.
• Denaturation of proteins refers to the disruption of their native structure due to physical or chemical changes.
• This process leads to the loss of biological activity while retaining the primary structure of the protein.

Causes of Denaturation:

1. Temperature: High temperatures can disrupt the hydrogen bonds that stabilize the secondary and tertiary structures of proteins.
2. pH Changes: Alterations in pH levels can affect the charge distribution in proteins, leading to changes in their conformation.
3. Chemical Agents: Chemicals such as strong acids or bases, organic solvents, and denaturing agents like urea or guanidine hydrochloride can induce denaturation.
4. Mechanical Agitation: Vigorous stirring or shaking can cause mechanical denaturation by breaking weak interactions within the protein structure.
5. Ionic Strength: Changes in salt concentration can interfere with protein stability.

Denaturation Process:

• Denaturation disrupts the secondary and tertiary structures of proteins while leaving the primary structure intact.
• The hydrogen bonds, disulfide bridges, and hydrophobic interactions that maintain the protein’s native shape are disturbed.
• This leads to the unfolding of globular proteins and the uncoiling of helical structures.
• Denatured proteins lose their biological activity and may aggregate or precipitate.

Examples of Denaturation:

1. Coagulation of Egg White: When egg white is heated (e.g., during cooking), the proteins within it denature. The coagulation or solidification of egg white is a result of denaturation.
2. Curdling of Milk: The action of bacteria in milk produces lactic acid, lowering the pH. This change in pH denatures milk proteins, causing them to aggregate and curdle.
3. Cooking Meat: Heating meat denatures the proteins in muscle fibers, resulting in changes in texture and flavor.

Enzymes

• Enzymes are biocatalysts that play a crucial role in facilitating and regulating chemical reactions in living organisms.
• These proteins are essential for life as they enable the coordination of various biochemical processes under mild physiological conditions.

Characteristics of Enzymes:

1. Protein Nature: Almost all enzymes are globular proteins, consisting of long chains of amino acids.
2. Specificity: Enzymes are highly specific, each catalyzing a particular reaction with a specific substrate or class of compounds.
3. Naming Convention: Enzymes are often named after the compound they act upon or the type of reaction they catalyze, typically ending with “-ase.” For example, maltase catalyzes the hydrolysis of maltose into glucose.
4. Substrate Specificity: Enzymes recognize and bind to their substrates through a specific active site, which complements the substrate’s shape and chemical properties.
5. Biological Catalysts: Enzymes accelerate chemical reactions by lowering the activation energy required for the reaction to occur.
6. Regulation: Enzyme activity can be regulated to maintain metabolic homeostasis within the cell.

Enzyme-Substrate Interaction:

• Enzymes interact with their substrates through a lock-and-key or induced-fit model. The active site of the enzyme is complementary to the substrate’s structure.
• Enzyme-substrate binding leads to the formation of an enzyme-substrate complex.
• Enzymes facilitate reactions by providing an alternative pathway with a lower activation energy, allowing the reaction to proceed more rapidly.

Types of Enzymes:

• Enzymes are classified based on the type of reaction they catalyze. Some common enzyme classes include:
  1. Oxidoreductases: Catalyze oxidation-reduction reactions by transferring electrons between molecules.
  2. Transferases: Facilitate the transfer of functional groups between substrates.
  3. Hydrolases: Promote the hydrolysis of bonds by adding water molecules.
  4. Lyases: Catalyze the removal of specific groups from substrates, resulting in the formation of double bonds.
  5. Isomerases: Convert substrates into isomeric forms by rearranging atoms within the molecules.
  6. Ligases: Catalyze the joining of two molecules, often using ATP as an energy source.

Importance of Enzymes:

• Enzymes are crucial for various biological processes, including digestion, energy production, DNA replication, and cell signaling.
• They allow reactions to occur at mild temperatures and pH levels, which are compatible with the body’s conditions.
• Enzymes contribute to metabolic regulation, ensuring that cellular processes proceed efficiently.
• Enzymes are used in industrial processes, such as food production, pharmaceuticals, and biofuel production, due to their high specificity and catalytic efficiency.

Mechanism of Enzyme Action

• Enzymes are essential biological catalysts that accelerate chemical reactions in living organisms.
• One of the key features of enzymes is their ability to lower the activation energy required for a reaction, making it easier for the reaction to proceed.
• This mechanism of action allows enzymes to facilitate reactions under mild physiological conditions.

Activation Energy and Enzymes:

• Activation energy (Ea) is the energy barrier that must be overcome for a chemical reaction to occur.
• Enzymes reduce the activation energy required for a reaction, making it energetically favorable for the reaction to proceed.
• Lowering the activation energy allows reactions to occur at biologically relevant temperatures and in a timely manner.

Enzyme-Substrate Interaction:

• Enzyme action begins with the binding of the enzyme to its specific substrate(s) at the active site.
• The active site is a region of the enzyme that complements the shape and chemical properties of the substrate.
• Enzyme-substrate binding forms an enzyme-substrate complex.

Catalytic Mechanism of Enzymes:

• Enzymes facilitate reactions by providing an alternative reaction pathway that has a lower activation energy.
• They do this through several mechanisms, including:
  1. Orientation: Enzymes orient substrates in a way that promotes the formation of the transition state, where the reaction is most likely to occur.
  2. Strain: Enzymes can induce strain on chemical bonds within the substrate, making it easier for those bonds to break.
  3. Proximity: Enzymes bring substrates into close proximity, increasing the likelihood of effective collisions between reactants.
  4. Acid-Base Catalysis: Some enzymes act as acids or bases, donating or accepting protons to facilitate specific reactions.
  5. Covalent Catalysis: Enzymes may form temporary covalent bonds with substrates, stabilizing the transition state.
• These mechanisms collectively result in a lower energy barrier (activation energy) for the reaction.

Specificity of Enzymes:

• Enzymes are highly specific for their substrates due to the complementary nature of the active site and the substrate.
• Enzyme-substrate specificity ensures that each enzyme catalyzes a specific reaction with high efficiency.

Vitamins

• Vitamins are organic compounds required in small amounts in our diet for the normal functioning, growth, and health of the organism.
• These vital nutrients are essential for various biochemical processes in the body and play a crucial role in preventing specific deficiency diseases.
• Vitamins cannot be synthesized in sufficient quantities by the human body and must be obtained through dietary sources.

Classification of Vitamins:

• Vitamins are classified into different groups, often denoted by letters such as A, B, C, D, E, and K.
• Some vitamins have sub-groups, such as B-complex vitamins (B1, B2, B6, B12), which are structurally related and often work together in metabolic processes.

Functions of Vitamins:

• Each vitamin has specific functions and roles in the body, including:
  1. Vitamin A: Essential for vision, immune function, and skin health.
  2. Vitamin B-complex: Includes various B vitamins that are involved in energy metabolism, nerve function, and the synthesis of red blood cells.
  3. Vitamin C: Important for collagen production, immune support, and as an antioxidant.
  4. Vitamin D: Essential for calcium absorption and bone health.
  5. Vitamin E: Acts as an antioxidant, protecting cells from damage.
  6. Vitamin K: Necessary for blood clotting and bone metabolism.

Dietary Sources of Vitamins:

• Vitamins are found in a variety of foods, including fruits, vegetables, dairy products, meats, and grains.
• A well-balanced diet that includes a variety of foods can provide an adequate intake of vitamins.
• Certain dietary restrictions or preferences (e.g., vegetarianism) may require special attention to ensure all vitamin needs are met.

Deficiency Diseases:

• Deficiency of specific vitamins can lead to various diseases, such as scurvy (vitamin C deficiency), rickets (vitamin D deficiency), and beriberi (vitamin B1 deficiency).
• These diseases highlight the essential roles that vitamins play in maintaining health.

Excess of Vitamins:

• While vitamins are essential for health, excess intake of certain vitamins can be harmful.
• Excessive consumption of fat-soluble vitamins (A, D, E, K) can lead to toxicity.
• It is important to obtain vitamins from a balanced diet and, in some cases, with the guidance of a healthcare professional.

Classification of Vitamins

Vitamins are essential organic compounds that play various roles in maintaining the health and proper functioning of the human body. They are classified into two main groups based on their solubility characteristics: fat-soluble vitamins and water-soluble vitamins.

Classification of Vitamins:

I. Fat-Soluble Vitamins:

• Fat-soluble vitamins are characterized by their ability to dissolve in fats and oils but being insoluble in water.
• They are stored in the body, primarily in the liver and adipose (fat) tissues, and can be utilized when needed.

1. Vitamin A (Retinol):

• Important for vision, immune function, and skin health.
• Found in animal-based foods such as liver, eggs, and dairy products, as well as in plant-based sources like carrots and sweet potatoes.

2. Vitamin D (Calciferol):

• Essential for calcium absorption and bone health.
• Synthesized in the skin upon exposure to sunlight and found in some foods like fatty fish and fortified dairy products.

3. Vitamin E (Tocopherol):

• Acts as an antioxidant, protecting cells from damage caused by free radicals.
• Found in various nuts, seeds, and vegetable oils.

4. Vitamin K (Phylloquinone):

• Necessary for blood clotting and bone metabolism.
• Found in leafy green vegetables, broccoli, and certain vegetable oils.

II. Water-Soluble Vitamins:

• Water-soluble vitamins are characterized by their ability to dissolve in water but being less likely to be stored in the body.
• These vitamins must be regularly obtained through the diet as they are readily excreted in urine.

1. Vitamin B Complex:

• The B-complex vitamins include several structurally related vitamins that often work together in metabolic processes.
• Some important B vitamins include:
  • B1 (Thiamine): Essential for energy metabolism and nerve function. Found in whole grains and legumes.
  • B2 (Riboflavin): Involved in energy production and antioxidant activity. Found in dairy products and leafy greens.
  • B6 (Pyridoxine): Important for amino acid metabolism and the nervous system. Found in meat, fish, and vegetables.
  • B12 (Cobalamin): Necessary for red blood cell formation and neurological function. Found in animal-based foods.
• Other B vitamins include B3 (niacin), B5 (pantothenic acid), B7 (biotin), and B9 (folate).

2. Vitamin C (Ascorbic Acid):

• Important for collagen production, immune support, and as an antioxidant.
• Found in citrus fruits, strawberries, bell peppers, and broccoli.

Table: Important Vitamins, Sources, and Deficiency Diseases

Nucleic Acids

Nucleic acids, specifically DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are crucial biomolecules that play a fundamental role in heredity and the transmission of genetic information from one generation to the next. These molecules are essential for storing, replicating, and transmitting genetic instructions that govern the development, structure, and functioning of living organisms.

1. DNA (Deoxyribonucleic Acid):
   • Structure: DNA is a double-stranded helical molecule made up of nucleotides. Each nucleotide consists of a phosphate group, a deoxyribose sugar molecule, and one of four nitrogenous bases: adenine (A), cytosine (C), guanine (G), or thymine (T). The two strands of DNA are connected by hydrogen bonds between complementary base pairs (A-T and C-G).
   • Function: DNA contains the genetic code that determines an organism’s traits and characteristics. It serves as a template for the synthesis of RNA, which, in turn, directs protein synthesis. DNA replication ensures that genetic information is accurately passed on during cell division.
   • Location: DNA is primarily found in the cell nucleus, but a small amount can also be found in mitochondria (mitochondrial DNA).
2. RNA (Ribonucleic Acid):
   • Structure: RNA is a single-stranded molecule also composed of nucleotides. Each nucleotide includes a phosphate group, a ribose sugar molecule, and one of four nitrogenous bases: adenine (A), cytosine (C), guanine (G), or uracil (U). RNA differs from DNA in both sugar composition (ribose vs. deoxyribose) and the presence of uracil instead of thymine.
   • Function: RNA plays a crucial role in protein synthesis. There are several types of RNA, including messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA), each with specific functions in the process of translating the genetic code from DNA into proteins.
   • Location: RNA is found in both the cell nucleus and the cytoplasm.

Functions of Nucleic Acids:

• Storage of genetic information.
• Transmission of genetic information from one generation to the next.
• Protein synthesis: DNA serves as a template for RNA synthesis (transcription), and RNA directs the synthesis of proteins (translation).
• Regulation of gene expression: Nucleic acids play a role in controlling when and how genes are turned on or off.
• Repair and maintenance of genetic material.

Chemical Composition of Nucleic Acids

Nucleic acids, such as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), have a complex chemical composition that includes several key components:

1. Pentose Sugar: Nucleic acids are composed of a sugar molecule as one of their components. In DNA, the sugar is 2-deoxyribose, while in RNA, it is ribose. The difference between these two sugars lies in the presence or absence of a hydroxyl (-OH) group at the 2′ position of the sugar ring. Deoxyribose lacks this hydroxyl group, hence the name “deoxyribose,” while ribose has it.
2. Phosphoric Acid (Phosphate Group): Nucleic acids contain phosphate groups, which are linked to the sugar molecules. These phosphate groups give nucleic acids their acidic nature.
3. Nitrogenous Bases: Nucleic acids also consist of nitrogen-containing heterocyclic compounds known as nitrogenous bases. There are four types of nitrogenous bases found in DNA: adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, the first three bases are the same (adenine, guanine, and cytosine), but instead of thymine, RNA contains uracil (U).
   • Adenine (A) pairs with thymine (T) in DNA or uracil (U) in RNA.
   • Guanine (G) pairs with cytosine (C) in both DNA and RNA.

These nitrogenous bases play a crucial role in encoding genetic information and determining the genetic code.

Overall Structure:

• Nucleic acids consist of long chains (polymers) of nucleotide units. Each nucleotide consists of a phosphate group, a pentose sugar (deoxyribose in DNA or ribose in RNA), and a nitrogenous base.
• The nitrogenous bases, arranged in a specific sequence along the sugar-phosphate backbone, form the genetic code that carries the instructions for the synthesis of proteins and other cellular processes.
• DNA is typically a double-stranded molecule with complementary base pairing (A-T and C-G) between the two strands. RNA is usually single-stranded.

Structure of Nucleic Acids

Nucleic acids, such as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), have a hierarchical structure that includes primary, secondary, and sometimes tertiary structures. This structure is essential for their function in storing and transmitting genetic information.

1. Primary Structure: The primary structure of a nucleic acid refers to the specific sequence of nucleotide units along the sugar-phosphate backbone. Nucleotides are the building blocks of nucleic acids and consist of three components: a phosphate group, a pentose sugar (deoxyribose in DNA or ribose in RNA), and a nitrogenous base. The sequence of nitrogenous bases, which includes adenine (A), thymine (T) or uracil (U), guanine (G), and cytosine (C), encodes genetic information. The order of these bases along the chain determines the genetic code.
2. Secondary Structure: The secondary structure of nucleic acids primarily involves the folding of the polynucleotide chain. In DNA, the most well-known secondary structure is the double-stranded helix, famously proposed by James Watson and Francis Crick. In this structure:
   • Two polynucleotide chains are wound around each other in a helical fashion.
   • The sugar-phosphate backbones are on the outside of the helix, forming the “rails” of the ladder-like structure.
   • The nitrogenous bases from one chain interact with those of the complementary chain in the center, forming the “rungs” of the ladder. These base pairs are held together by hydrogen bonds.
   • Adenine (A) always pairs with thymine (T) in DNA via two hydrogen bonds, while guanine (G) pairs with cytosine (C) via three hydrogen bonds. This complementary base pairing ensures the stability of the DNA double helix.
   In RNA, the secondary structure can also include single-stranded regions and folding patterns that lead to various functional shapes. For example, t-RNA (transfer RNA) adopts a cloverleaf-like structure, and r-RNA (ribosomal RNA) contributes to the structure of ribosomes.
3. Tertiary Structure (For Some RNAs): While the secondary structure of DNA is typically a double helix, some RNA molecules exhibit tertiary structures. Tertiary structure refers to the three-dimensional arrangement of the RNA molecule, often involving complex folding and interactions between distant parts of the chain. This folding is crucial for the function of some RNA molecules, such as ribozymes and certain non-coding RNAs.

DNA Fingerprinting

DNA fingerprinting, also known as DNA profiling or DNA typing, is a powerful forensic technique used to identify individuals based on their unique DNA characteristics. It relies on the fact that every person has a distinct DNA sequence, with the exception of identical twins. DNA fingerprinting has widespread applications in various fields, including forensics, paternity testing, and genetic research.

Here’s how DNA fingerprinting works:

1. Sample Collection: The process begins with the collection of a biological sample containing DNA. Common sources of DNA samples include blood, saliva, hair, skin cells, and bodily fluids.
2. DNA Extraction: The DNA is extracted from the collected sample using specialized laboratory techniques. This process involves breaking open the cells and isolating the DNA molecules.
3. DNA Amplification: DNA fingerprinting often involves amplifying specific regions of the DNA to increase the amount of material available for analysis. Polymerase chain reaction (PCR) is commonly used for this purpose.
4. DNA Digestion: The amplified DNA is then digested using restriction enzymes. These enzymes cleave the DNA at specific recognition sequences, resulting in the creation of smaller DNA fragments.
5. Electrophoresis: The DNA fragments are separated by size using a technique called gel electrophoresis. In this process, an electric current is applied to a gel matrix, causing the DNA fragments to migrate through the gel based on their size. Smaller fragments move faster and travel farther through the gel.
6. Southern Blotting (Optional): In some cases, Southern blotting may be employed to transfer the separated DNA fragments from the gel onto a membrane, where they can be further analyzed.
7. DNA Probing: The separated DNA fragments are then hybridized with a DNA probe. The probe is a labeled piece of DNA that is complementary to a specific target sequence within the sample DNA.
8. Visualization: After probing, the DNA fragments are visualized using various methods, such as autoradiography or fluorescent imaging. This results in a pattern of bands on an autoradiogram or an image.
9. Analysis: The unique pattern of bands in the DNA fingerprint is analyzed to create a genetic profile for the individual. This profile can be compared to profiles from other samples or individuals to determine relatedness or identity.

Applications of DNA fingerprinting include:

• Forensic Identification: DNA fingerprinting is widely used in criminal investigations to match suspects to crime scene evidence. It helps establish guilt or innocence and can exonerate wrongly accused individuals.
• Paternity Testing: DNA fingerprinting can determine paternity with a high degree of accuracy by comparing the child’s DNA profile to that of the alleged father.
• Missing Persons and Disaster Victim Identification: DNA profiling is crucial in identifying missing persons or victims of natural disasters and accidents, where traditional identification methods may be challenging.
• Biological and Genetic Research: DNA fingerprinting is used in genetics research to study genetic variations, population genetics, and evolutionary relationships.

DNA fingerprinting has revolutionized the fields of law enforcement and genetics, providing a reliable and highly accurate method for individual identification and genetic analysis.

Biological Functions of Nucleic Acids

Nucleic acids, particularly DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), serve crucial biological functions in living organisms. These functions are essential for the maintenance, growth, and reproduction of cells and organisms. Here are some of the key biological functions of nucleic acids:

1. Storage of Genetic Information: DNA serves as the repository of genetic information in all known living organisms. It contains the instructions required for the development, functioning, and reproduction of an organism. The sequence of nucleotide bases in DNA carries the genetic code that determines an individual’s traits and characteristics. This genetic information is passed from one generation to the next, ensuring the continuity of species.
2. Transmission of Genetic Information: DNA plays a central role in the transmission of genetic information from parent to offspring. During cell division (e.g., mitosis and meiosis), DNA molecules are faithfully replicated, and identical copies are distributed to daughter cells. This ensures that each new cell or organism inherits the same genetic material as the parent.
3. Protein Synthesis: One of the most critical functions of nucleic acids, particularly RNA, is protein synthesis. RNA molecules, including messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA), are involved in various stages of protein synthesis. The process begins with the transcription of DNA into mRNA, followed by the translation of mRNA into proteins. In this way, nucleic acids are directly responsible for the synthesis of all cellular proteins, which are essential for the structure and function of cells.
4. Gene Expression: Nucleic acids regulate the expression of genes, controlling when and how genes are activated or repressed. Gene expression is a tightly regulated process that ensures the production of specific proteins at the right time and in the right quantities. This regulation is essential for cellular functions, differentiation, and response to environmental cues.
5. Cellular Reproduction: DNA replication is a fundamental process in the cell cycle, enabling the accurate duplication of genetic material before cell division. During mitosis and meiosis, DNA replication ensures that each daughter cell receives a complete and identical set of chromosomes.
6. Heredity and Evolution: Nucleic acids, through their role in storing genetic information, are responsible for the hereditary transmission of traits from one generation to the next. Genetic variations, mutations, and recombination events in DNA contribute to the diversity of species and drive the process of evolution.
7. RNA Functions: RNA molecules have diverse functions beyond protein synthesis. For example, small RNAs, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), are involved in gene regulation and post-transcriptional control. They can silence or degrade specific mRNA molecules, influencing gene expression.
8. Repair and Maintenance: DNA repair mechanisms ensure the integrity of the genetic material by correcting errors, mutations, or damage caused by various factors, including radiation, chemicals, and metabolic processes.

Hormones

Hormones are vital signaling molecules that regulate various physiological processes in the body. They are produced by specialized glands called endocrine glands and are released into the bloodstream, where they travel to target tissues or organs to elicit specific responses. Hormones play a crucial role in maintaining homeostasis, growth and development, metabolism, and various other functions in the body.

Here are some key points about hormones:

1. Chemical Nature: Hormones can have diverse chemical structures, including steroids (e.g., estrogens and androgens), polypeptides (e.g., insulin and endorphins), amino acid derivatives (e.g., epinephrine and norepinephrine), and others. These different chemical structures determine the hormone’s functions and interactions with target cells.
2. Production and Release: Hormones are produced by endocrine glands, such as the thyroid gland, adrenal glands, pancreas, and gonads (testes and ovaries). These glands release hormones directly into the bloodstream. The secretion of hormones is tightly regulated by feedback mechanisms, ensuring that hormone levels remain within specific ranges.
3. Transport: Once released into the bloodstream, hormones circulate throughout the body and reach their target tissues or cells. Hormones interact with specific receptors on the surface or within target cells, initiating various physiological responses.
4. Functions: Hormones have diverse functions in the body. Some of their roles include:
   • Regulation of Blood Glucose: Hormones like insulin and glucagon regulate blood glucose levels. Insulin promotes glucose uptake by cells, while glucagon raises blood glucose levels by stimulating the release of stored glucose.
   • Stress Response: Hormones like epinephrine (adrenaline) and norepinephrine are involved in the body’s response to stress. They increase heart rate, blood pressure, and alertness, preparing the body for a “fight or flight” response.
   • Growth and Development: Growth hormones, produced by the pituitary gland, promote growth and development during childhood and adolescence.
   • Reproductive Functions: Sex hormones, such as testosterone (male) and estradiol (female), regulate the development of secondary sexual characteristics and play roles in the menstrual cycle, pregnancy, and fertility.
   • Metabolism: Thyroid hormones, like thyroxine (T4) and triiodothyronine (T3), influence metabolic rate and energy expenditure. Abnormal thyroid hormone levels can lead to conditions like hypothyroidism or hyperthyroidism.
   • Fluid and Electrolyte Balance: Hormones like aldosterone, produced by the adrenal glands, control the balance of water and electrolytes (e.g., sodium and potassium) in the body.
5. Diseases and Disorders: Hormonal imbalances can lead to various health conditions. For example, insulin deficiency or resistance can result in diabetes mellitus, while an excess of thyroid hormones can cause hyperthyroidism. Hormone replacement therapies are used to manage hormonal deficiencies or imbalances.
6. Hormone Regulation: Hormone secretion is controlled by feedback mechanisms involving the hypothalamus, pituitary gland, and target organs. Negative feedback loops help maintain hormone levels within a narrow range, ensuring the body’s proper functioning.