CELL METABOLISM

• Metabolism

  Total cellular chemical changes
• Anabolism

  Process of building up
• Catabolism

  Process of breaking down
• Calorie

  Measure of energy contained in food
• ATP

  Energy source available to the cell
• Glycolysis

  1. Breakdown of glucose

  2. Anaerobic or aerobic process

  3. Final outcome: 2 pyruvic acid molecules, 2 ATP molecules (anaerobic), 8 ATP molecules (aerobic)
• The Krebs Citric Acid Cycle

  1. Pyruvic Acid > Acetic Acid > Acetyl-CoA

  2. Acetyl-CoA enters Krebs cycle in mitochondria

  3. Final outcome: 6 CO2, 8 NADH2, 2 FADH2, 2 ATP (GTP)
• The Electron Transport (Transfer) System

  1. Series of reduction/oxidation reactions

  2. Requires O2

  3. Electron carriers

  4. Number of ATP molecules dependent on electron carrier

  5. Water is a waste product
• Fermentation

  1. Yeast breaks down glucose anaerobically

  2. Pyruvic acid is broken down by decarboxylase to form carbon dioxide and acetaldehyde

  3. Final products: 2 ATP, CO2, ethyl alcohol
• Anaerobic Production of ATP by Muscles

  1. Pyruvic acid converted to lactic acid

  2. Accumulation of lactic acid causes fatigue in muscles

  3. When oxygen is supplied, lactic acid turns back into pyruvic acid

  4. 2 ATP produced per glucose molecule
• Carbohydrates

  Fit into cellular furnace at same level as glucose, can be stored in liver or as fat
• Fats

  Digested into fatty acids and glycerol, glycerol enters at PGA stage of glycolysis, fatty acids enter Krebs citric acid cycle
• Proteins

  Digested into amino acids, enter into Krebs cycle at different stages dependent on chemical structure
• Cellular Reproduction

  Process of cell duplication, Mitosis: duplication of genetic material, Cytokinesis: duplication of organelles, Meiosis: reduction division only in gonads
• DNA Molecule

  Double helical chain of nucleotides with phosphate group, five-carbon sugars (deoxyribose), and nitrogen-containing bases (pyrimidines and purines)
• DNA Molecule

  • Pyrimidines pair with purines, chains held together by hydrogen bonds
• Gene

  Sequence of base pairs that codes for polypeptide or protein
• Human Genome Project: 3 billion base pairs that code for 30,000 genes
• Duplication of DNA Molecule

  Helicase separates at hydrogen bonds, DNA polymerase adds new nucleotides
• Cell Cycle

  Interphase, Mitosis, Cytokinesis
• Interphase

  Time between divisions, G1: Primary growth phase, S: DNA duplication, G2: Centrioles complete duplication, mitochondria replicate, chromosomes condense and coil
• Mitosis

  1. Prophase: Chromosomes become visible as chromatids, two kinetochores at centromere, centrioles move to opposite poles, nuclear membrane breaks down, microtubules attach kinetochores to spindle

  2. Metaphase: Chromatids align at equator of cell, centromere divides

  3. Anaphase: Divided centromere pulls chromatids to opposite pole, cytokinesis begins

  4. Telophase: Chromosomes uncoil and decondense, spindle apparatus breaks down, new nuclear membrane forms, cytokinesis nearly complete
• Cytokinesis

  1. Animal cells: Cleavage furrow forms, cell is pinched into daughter cells

  2. Plant cells: Cell plate forms at equator, cell plate becomes new cell wall
• Meiosis

  1. Occurs only in the gonads, reduces genetic material from diploid to haploid, two divisions resulting in four cells

  2. Prophase I: Homologous chromosomes pair and cross over

  3. Metaphase I: Chromosomes align along equator

  4. Anaphase I: Centromeres pulled to poles, one member to each pole

  5. Telophase I: One of each pair is at each pole

  6. Prophase II: Spindle forms, centrioles move to poles

  7. Metaphase II: Chromosomes line up at equator

  8. Anaphase II: Centromeres divide

  9. Telophase II: Chromatids at each pole, new nuclear membrane forms
• Gametogenesis

  • Spermatogenesis: Four cells produced, develop into sperm
  • Oogenesis: Four cells produced, only one becomes functional egg