Part 2 – Biochemistry

Introduction to Biochemistry

Biochemistry is the study of chemical processes and molecules that are essential for living organisms. Understanding biochemistry is fundamental for grasping how the human body functions at the molecular level.

• Biochemistry explores the structure, function, and interactions of biomolecules.

• Key classes of biomolecules: water, salts, acids, bases, carbohydrates, lipids, proteins, and nucleic acids.

• Biochemical reactions underpin metabolism and cellular activity.

2.6 Inorganic Compounds

Characteristics of Inorganic Compounds

Inorganic compounds are typically small molecules that do not contain carbon-hydrogen (C-H) bonds. They play vital roles in physiological processes.

• Water: Most abundant inorganic compound in living organisms.

• Salts: Ionic compounds important for nerve conduction and muscle contraction.

• Acids and Bases: Regulate pH and participate in metabolic reactions.

• Functions: Solvent, transport medium, temperature regulation, and chemical reactivity.

Water

Properties and Importance of Water

Water is essential for life due to its unique chemical and physical properties.

• High heat capacity: Absorbs and releases heat slowly, helping maintain body temperature.

• High heat of vaporization: Evaporation of water requires significant energy, aiding in cooling mechanisms (e.g., sweating).

• Polar solvent properties: Dissolves ionic and polar substances, facilitating transport and chemical reactions.

• Reactivity: Participates in hydrolysis and dehydration synthesis reactions.

• Cushioning: Protects organs by providing a fluid cushion (e.g., cerebrospinal fluid).

Salts

Role and Properties of Salts

Salts are ionic compounds that dissociate in water to form electrolytes, which are crucial for physiological functions.

• Electrolytes: Conduct electrical currents in solution.

• Common physiological salts: NaCl (sodium chloride), KCl (potassium chloride), CaCO3 (calcium carbonate), CaPO4 (calcium phosphate).

• Functions: Nerve impulse transmission, muscle contraction, and maintaining fluid balance.

Acids and Bases

Definitions and Functions

Acids and bases are substances that alter the concentration of hydrogen ions (H+) in solution, affecting pH and metabolic processes.

• Acids: Proton donors; release H+ ions in solution.

• Bases: Proton acceptors; take up H+ ions or release OH- ions.

• Examples: HCl (hydrochloric acid), NaOH (sodium hydroxide), H2CO3 (carbonic acid).

pH Scale

The pH scale measures the concentration of hydrogen ions in a solution, ranging from 0 (most acidic) to 14 (most basic).

• Neutral pH: 7

• Acidic: pH < 7

• Basic (alkaline): pH > 7

Equation:

Buffers

Buffers are systems that resist changes in pH by absorbing or releasing H+ ions.

• Important for maintaining homeostasis in blood and tissues.

• Example: Bicarbonate buffer system.

2.7 Organic Compounds: Synthesis and Hydrolysis

Organic Molecules and Reactions

Organic compounds contain carbon and are the basis of life. Their synthesis and breakdown are essential for metabolism.

• Dehydration synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

• Main classes: Carbohydrates, lipids, proteins, nucleic acids.

2.8 Carbohydrates

Structure and Function of Carbohydrates

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as a primary energy source for cells.

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides joined (e.g., sucrose, lactose).

• Polysaccharides: Long chains of monosaccharides (e.g., glycogen, starch).

• Functions: Energy storage, structural support.

Carbohydrate Molecules Important to the Body

2.9 Lipids

Types and Functions of Lipids

Lipids are hydrophobic organic molecules that include fats, oils, and steroids. They are important for energy storage, membrane structure, and signaling.

• Triglycerides: Composed of glycerol and three fatty acids; main energy storage form.

• Phospholipids: Major component of cell membranes; contain a phosphate group.

• Steroids: Four-ring structure; includes cholesterol and hormones.

Saturated and Unsaturated Fatty Acids

Phospholipid Structure

• Hydrophilic (water-loving) head and hydrophobic (water-fearing) tails.

• Form bilayers in cell membranes.

2.10 Proteins

Structure and Function of Proteins

Proteins are polymers of amino acids and perform a wide variety of functions in the body.

• Structural proteins: Provide support (e.g., collagen).

• Enzymes: Catalyze biochemical reactions.

• Transport proteins: Move substances across membranes.

• Contractile proteins: Enable movement (e.g., actin, myosin).

Levels of Protein Structure

• Primary: Sequence of amino acids.

• Secondary: Alpha helices and beta sheets formed by hydrogen bonding.

• Tertiary: Three-dimensional folding due to side chain interactions.

• Quaternary: Association of multiple polypeptide chains.

Protein Denaturation

• Loss of structure and function due to changes in pH, temperature, or chemicals.

• Denatured proteins cannot perform their biological roles.

Enzymes and Enzyme Activity

Role of Enzymes

Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy.

• Highly specific for their substrates.

• Not consumed in the reaction.

• Activity affected by temperature, pH, and substrate concentration.

Equation:

2.11 Nucleic Acids

Structure and Function of Nucleic Acids

Nucleic acids store and transmit genetic information. The two main types are DNA and RNA.

• DNA (Deoxyribonucleic acid): Double helix; stores genetic instructions.

• RNA (Ribonucleic acid): Single-stranded; involved in protein synthesis.

• Composed of nucleotides: phosphate group, sugar, nitrogenous base.

2.12 ATP (Adenosine Triphosphate)

Role of ATP in Cellular Energy

ATP is the primary energy carrier in cells, providing energy for cellular processes.

• Composed of adenine, ribose, and three phosphate groups.

• Energy released when the terminal phosphate bond is broken.

Equation:

• ATP drives cellular work: transport, mechanical, and chemical activities.

Clinical – Homeostatic Imbalance

Importance of Homeostasis

Disruption in biochemical balance can lead to disease. Maintaining homeostasis is essential for health.

• Imbalances in pH, electrolytes, or energy metabolism can cause clinical symptoms.

• Examples: Acidosis, alkalosis, dehydration.

Additional info: Some explanations and table entries were expanded for clarity and completeness.