Metabolism and Genetic Biochemistry

Metabolism

• Definition: The set of life-sustaining chemical reactions in organisms, divided into catabolism and anabolism.
• Catabolism:
  • Breakdown of molecules to obtain energy.
  • Produces ATP, NADH, and FADH2.
  • Examples: Glycolysis, Krebs cycle.
• Anabolism:
  • Synthesis of complex molecules from simpler ones.
  • Consumes energy (ATP).
  • Examples: Protein synthesis, gluconeogenesis.
• Metabolic Pathways:
  • Series of chemical reactions in a cell.
  • Regulated by enzymes and feedback mechanisms.
• Energy Currency:
  • ATP (adenosine triphosphate) is the primary energy carrier.

Genetic Biochemistry

• DNA Structure:
  • Double helix composed of nucleotides (adenine, thymine, cytosine, guanine).
• DNA Replication:
  • Semi-conservative process, involves helicase, DNA polymerase, and ligase.
• Transcription:
  • Synthesis of RNA from a DNA template, involving RNA polymerase.
  • Produces mRNA, tRNA, and rRNA.
• Translation:
  • Process of synthesizing proteins from mRNA.
  • Ribosomes read mRNA and tRNA brings amino acids.
• Gene Regulation:
  • Mechanisms controlling gene expression (e.g., transcription factors).

Lipid Biochemistry

• Types of Lipids:
  • Fatty acids: Saturated and unsaturated.
  • Triglycerides: Glycerol + three fatty acids.
  • Phospholipids: Major components of cell membranes.
  • Steroids: Four fused carbon rings (e.g., cholesterol).
• Functions:
  • Energy storage (triglycerides).
  • Cell membrane structure (phospholipids).
  • Signaling molecules (hormones like steroids).
• Lipid Metabolism:
  • Beta-oxidation: Breakdown of fatty acids for energy.
  • Lipogenesis: Synthesis of fatty acids from acetyl-CoA.

Enzyme Function

• Definition: Biological catalysts that speed up chemical reactions without being consumed.
• Enzyme Structure:
  • Active site: Specific region where substrate binds.
  • Coenzymes and cofactors: Non-protein molecules aiding enzyme activity.
• Enzyme Kinetics:
  • Michaelis-Menten kinetics: Describes the rate of enzymatic reactions with respect to substrate concentration.
  • Vmax: Maximum rate of reaction.
  • Km: Substrate concentration at which reaction rate is half of Vmax.
• Factors Affecting Enzyme Activity:
  • Temperature: Optimal temperature enhances activity; extreme heat denatures enzymes.
  • pH: Each enzyme has an optimal pH for activity.
  • Inhibitors:
    • Competitive: Compete with substrate for active site.
    • Non-competitive: Bind to enzyme or complex, reducing activity.
• Regulation:
  • Allosteric regulation: Binding of molecules at sites other than the active site alters activity.
  • Feedback inhibition: End product of a pathway inhibits an earlier step.

Metabolism

• Encompasses all life-sustaining chemical reactions in organisms, categorized into catabolism and anabolism.
• Catabolism involves the breakdown of molecules to release energy, producing ATP, NADH, and FADH2. Key processes include glycolysis and the Krebs cycle.
• Anabolism focuses on synthesizing complex molecules from simpler ones, consuming energy in the form of ATP. Examples include protein synthesis and gluconeogenesis.
• Metabolic pathways consist of a series of chemical reactions regulated by enzymes and feedback mechanisms, ensuring metabolic stability.
• ATP (adenosine triphosphate) serves as the primary energy currency, transferring energy within cells for various biosynthetic processes.

Genetic Biochemistry

• DNA is structured as a double helix made up of four nucleotides: adenine, thymine, cytosine, and guanine.
• DNA replication is a semi-conservative process that requires enzymes such as helicase, DNA polymerase, and ligase to create two identical DNA strands.
• Transcription is the process of synthesizing RNA from a DNA template, primarily facilitated by RNA polymerase, resulting in mRNA, tRNA, and rRNA.
• Translation involves synthesizing proteins based on mRNA sequences, wherein ribosomes interpret mRNA and tRNA delivers the corresponding amino acids.
• Gene regulation includes various mechanisms that control gene expression, with transcription factors playing a key role in ensuring appropriate protein levels.

Lipid Biochemistry

• Types of lipids encompass several categories:
  • Fatty acids can be saturated or unsaturated.
  • Triglycerides consist of glycerol linked to three fatty acids, primarily used for energy storage.
  • Phospholipids are essential components of cell membranes, forming lipid bilayers.
  • Steroids are characterized by four fused carbon rings, with cholesterol being a prominent example.
• Functions of lipids include energy storage (via triglycerides), structural support in cell membranes (via phospholipids), and signaling roles as hormones (like steroids).
• Lipid metabolism involves processes such as beta-oxidation, which breaks down fatty acids for energy, and lipogenesis, which synthesizes fatty acids from acetyl-CoA.

Enzyme Function

• Enzymes are biological catalysts that accelerate chemical reactions without undergoing any permanent changes.
• Enzyme structure features an active site for substrate binding, while coenzymes and cofactors (non-protein molecules) assist in enzyme functionality.
• Enzyme kinetics can be described by Michaelis-Menten kinetics, highlighting:
  • Vmax, the maximum rate of reaction.
  • Km, the substrate concentration at which the reaction rate is half of Vmax.
• Factors affecting enzyme activity include:
  • Temperature, with an optimal range enhancing activity; high temperatures may denature enzymes.
  • pH, with each enzyme having a specific pH range for optimal function.
  • Inhibitors, which may be competitive (competing with the substrate for active sites) or non-competitive (binding to the enzyme or enzyme-substrate complex, reducing activity).
• Enzyme activity can be regulated through:
  • Allosteric regulation, where molecule binding at sites other than the active site alters enzyme function.
  • Feedback inhibition, where the end product of a metabolic pathway inhibits an earlier step, serving a regulatory function.

Explore the fundamental concepts of metabolism and genetic biochemistry through this quiz. Test your understanding of catabolism, anabolism, and the structure and functions of DNA. Challenge yourself with questions on metabolic pathways, energy currency, and the processes of transcription and translation.