뒤로Cellular Metabolism and Genetic Information - Anatomy & Physiology
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Metabolism is the sum of all chemical reactions in the body.
Anabolism builds small molecules into larger ones and requires energy. Catabolism breaks down larger molecules into smaller ones and releases energy.
Dehydration synthesis is an anabolic process where smaller molecules are joined to form larger ones, producing water in the process.
Hydrolysis is a catabolic process that uses water to split larger molecules into smaller ones, the reverse of dehydration synthesis.
Enzymes are protein catalysts that increase reaction rates by lowering activation energy and are specific to substrates.
A rate-limiting enzyme controls the speed of a metabolic pathway, often the first enzyme, and can be inhibited by the pathway's end product.
Cofactors are non-protein substances that activate enzymes. Coenzymes are organic cofactors, often vitamins.
Denaturation is the irreversible inactivation of enzymes caused by heat, radiation, extreme pH, or chemicals.
ATP (adenosine triphosphate) carries energy in cells; energy is released when high-energy phosphate bonds are broken.
ATP loses a phosphate to become ADP, releasing energy; ADP is phosphorylated back to ATP using energy from cellular respiration.
Glycolysis (anaerobic), citric acid cycle (aerobic), and electron transport chain (aerobic).
Glycolysis breaks down glucose into two pyruvic acid molecules in the cytosol, producing 2 ATP without oxygen.
Without oxygen, NADH transfers electrons back to pyruvic acid forming lactic acid, which inhibits glycolysis and reduces ATP production.
Acetyl CoA combines with oxaloacetic acid to produce citric acid, generating 1 ATP, hydrogen atoms for NAD and FAD, and CO2 per cycle.
High-energy electrons from NADH and FADH2 pass through enzyme complexes, driving ATP synthase to phosphorylate ADP to ATP; oxygen is the final electron acceptor.
Excess glucose is stored as glycogen in liver and muscle cells or converted to fat in adipose tissue.
DNA stores genetic information in nucleotide sequences that instruct cells how to synthesize proteins.
DNA is a double helix with two antiparallel strands of nucleotides; bases pair specifically (A-T, C-G) via hydrogen bonds.
DNA replication produces an exact copy of DNA during interphase by unwinding strands and pairing new nucleotides with the help of DNA polymerase.
Transcription copies a DNA sequence into messenger RNA (mRNA) in the nucleus, catalyzed by RNA polymerase.
Translation converts mRNA's genetic code into a sequence of amino acids at the ribosome, using transfer RNA (tRNA) to bring amino acids.
mRNA codons (3-base sequences) specify amino acids; tRNA anticodons bind complementary codons to add correct amino acids to the growing protein.
Mutations are changes in DNA sequence that can be spontaneous or induced; they may be harmless, harmful (e.g., sickle cell disease), or rarely beneficial.
DNA repair enzymes correct mismatches; redundancy in the genetic code and having two chromosome copies help maintain health despite mutations.