Introduction to Biochemistry

Introduction to Biochemistry

• Biochemistry is the study of the chemical processes within and relating to living organisms.
• It encompasses a wide range of topics, including the structure and function of biomolecules, metabolic pathways, and the regulation of these processes.
• Biochemistry plays a crucial role in understanding health, disease, and the development of new therapies.

Biomolecules

• Biomolecules are the fundamental building blocks of all living organisms.
• Four major classes: carbohydrates, lipids, proteins, and nucleic acids.
  • Carbohydrates: primarily composed of carbon, hydrogen, and oxygen; provide energy and structural support. Subclasses include monosaccharides, disaccharides, and polysaccharides.
  • Lipids: diverse group of hydrophobic molecules, including fats, oils, and steroids; crucial for energy storage, insulation, and membrane structure. Examples include triglycerides, phospholipids, and cholesterol.
  • Proteins: polymers of amino acids; crucial for diverse functions in the body, including catalysis (enzymes), transport, and structural support. Structure is complex; primary, secondary, tertiary and quaternary structures.
  • Nucleic Acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA); carry genetic information and are essential for protein synthesis. DNA stores genetic information, while RNA translates this information.

Cellular Metabolism

• Cellular metabolism encompasses all the biochemical reactions occurring within a cell.
• Two major types:
  • Catabolism: the breakdown of complex molecules into simpler ones, releasing energy.
  • Anabolism: the synthesis of complex molecules from simpler ones, requiring energy input.
• Key metabolic pathways, including glycolysis, the citric acid cycle, and oxidative phosphorylation, which are central to energy production.
• Regulation of metabolic pathways is critical for maintaining homeostasis.

Enzymes

• Enzymes are biological catalysts, typically proteins, accelerating biochemical reactions without being consumed.
• They work by lowering the activation energy of a reaction, facilitating the conversion of substrates to products.
• Characteristics of enzymes include specificity, sensitivity to environmental factors (e.g., temperature, pH), and regulation.

Protein Structure and Function

• Proteins have diverse roles, including structural support (collagen), transporting molecules (hemoglobin), catalyzing reactions (enzymes), and signaling (hormones).
• Primary structure: amino acid sequence.
• Secondary structure: localized folding patterns (α-helices, β-sheets).
• Tertiary structure: overall 3D shape of the polypeptide chain, stabilized by various interactions.
• Quaternary structure: arrangement of multiple polypeptide chains in a functional protein.

Nucleic Acids

• DNA carries genetic information.
• RNA plays a vital role in protein synthesis.
• DNA structure: double helix composed of nucleotides, each with a sugar, a phosphate group, and a nitrogenous base. DNA bases are adenine, guanine, cytosine, and thymine.
• RNA structure: single-stranded, containing nucleotides with a different sugar (ribose) and uracil instead of thymine.

Carbohydrate Metabolism

• Carbohydrates are the primary source of energy for the body.
• Glucose is a key metabolic substrate.
• Glycolysis: the breakdown of glucose to pyruvate, producing ATP.
• Gluconeogenesis: the synthesis of glucose from non-carbohydrate precursors.
• Glycogenolysis: breakdown of glycogen to glucose.

Lipid Metabolism

• Lipids store energy, form membranes, and act as hormones.
• Fatty acid oxidation: a key metabolic pathway for energy production.
• Lipogenesis: synthesis of fatty acids.

Cellular Respiration

• Cellular respiration is a series of metabolic reactions that convert nutrients into usable energy (ATP).
• Occurs in the mitochondria.
• It proceeds through various stages, including glycolysis, the Krebs cycle/Citric Acid cycle, and oxidative phosphorylation.

Cell Signaling

• Cells communicate with each other through various pathways.
• Signaling pathways involve cascades of biochemical reactions, often involving protein-protein interactions.
• Key components include receptors, intracellular signaling molecules, and effectors.

Regulation of Biochemical Processes

• Many of these processes are highly regulated to maintain homeostasis.
• Regulation often occurs at the level of enzyme activity or gene expression.
• Feedback mechanisms are crucial for maintaining balance.