Cellular Metabolism and Reproduction: Mitosis and Meiosis

1. Chapter 4 Cellular Metabolism and Reproduction: Mitosis and Meiosis

2. Introduction to Cellular 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

3. Cellular Metabolism or Biochemical Respiration

4. Glycolysis • Breakdown of glucose • Anaerobic or aerobic process • Final outcome • 2 pyruvic acid molecules, 2 ATP molecules (anaerobic), 8 ATP molecules (aerobic)

5. The Krebs Citric Acid Cycle • Pyruvic Acid > Acetic Acid > Acetyl-CoA • Acetyl-CoA enters Krebs cycle in mitochondria • Final outcome • 6 CO2, 8 NADH2, 2 FADH2, 2 ATP (GTP)

6. The Electron Transport (Transfer) System • Series of reduction/oxidation reactions • Requires O2 • Electron carriers • Number of ATP molecules dependent on electron carrier • Water is a waste product

7. Summary of ATP Production • During glycolysis, the citric acid cycle, and electron transport • Glycolysis: 8 ATP (aerobic) • Krebs cycle and electron transport • 28 ATP + 2 GTP or • 30 ATP • 1 glucose molecule yields 38 ATP

8. Anaerobic Respiration

9. Fermentation • Yeast breaks down glucose anaerobically • Pyruvic acid broken down by decarboxylase • Forms carbon dioxide and acetaldehyde • Final products: 2 ATP, CO2, ethyl alcohol

10. Anaerobic Production of ATP by Muscles • Pyruvic acid converted to lactic acid • Accumulation of lactic acid causes fatigue in muscles • When oxygen supplied, lactic acid turns back into pyruvic acid • 2 ATP produced per glucose molecule

11. Production of ATP from General Food Compounds

12. Production of ATP from General Food Compounds (cont’d.) • 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

13. Production of ATP from General Food Compounds (cont’d.) • Proteins digested into amino acids • Enter into Krebs cycle at different stages • Dependent on chemical structure

14. Introduction to Cellular Reproduction

15. Introduction to Cellular Reproduction (cont’d.) • Process of cell duplication • Mitosis: duplication of genetic material • Cytokinesis: duplication of organelles • Meiosis: reduction division only in gonads

16. The Structure of the DNA Molecule

17. The History of the Discovery of DNA • Friedrich Miescher, 1869: first discovery • P.A. Levine, 1920s: composition • Rosalind Franklin: helical structure • Watson and Crick: three-dimensional structure

18. The Anatomy of the DNA Molecule • Double helical chain of nucleotides • Phosphate group • Five-carbon sugars (deoxyribose) • Nitrogen-containing base • Pyrimidines (thymine and cytosine) • Purines (adenine and guanine) • Pyrimidines pair with purines • Chains held together by hydrogen bonds

19. The Anatomy of the DNA Molecule (cont’d.) • 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

20. The Cell Cycle

21. Introduction • All reproduction begins at cellular level • Interphase • Previously called resting stage • Mitosis • Cytokinesis

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

23. Mitosis • Prophase • Chromosomes become visible as chromatids joined by centromere • Two kinetochores at the centromere • Centrioles move to opposite poles • Nuclear membrane breaks down • Microtubules attach kinetochores to spindle

24. Mitosis (cont’d.) • Metaphase • Chromatids align at equator of cell • Centromere divides

25. Mitosis (cont’d.) • Anaphase • Divided centromere pulls chromatids to opposite pole • Cytokinesis begins

26. Mitosis (cont’d.) • Telophase • Chromosomes uncoil and decondense • Spindle apparatus breaks down • New nuclear membrane forms • Cytokinesis nearly complete

27. Animation – Mitosis • Stop and watch a 3-D presentation of mitosis. Click Here to Play Mitosis Animation

28. Cytokinesis • Animal cells • Cleavage furrow forms • Cell is pinched into daughter cells • Plant cells • Cell plate forms at equator • Cell plate becomes new cell wall

29. Meiosis: A Reduction Division

30. Introduction • Occurs only in the gonads • Reduces genetic material from diploid to haploid • Two divisions resulting in four cells

31. Stages of Meiosis • Prophase I: homologous chromosomes pair and cross over • Metaphase I: chromosomes align along equator • Anaphase I: centromeres pulled to poles • One member to each pole • Telophase I: one of each pair is at each pole

32. Stages of Meiosis (cont’d.) • Prophase II: spindle forms; centrioles move to poles • Metaphase II: chromosomes line up at equator • Anaphase II: centromeres divide • Telophase II: chromatids at each pole; new nuclear membrane forms

33. Animation – Meiosis • Now that you have learned about the stages of meiosis, watch the meiosis animation for a visual of this process. Click Here to Play Meiosis Animation

34. Gametogenesis: The Formation of the Sex Cells

35. Gametogenesis: The Formation of the Sex Cells (cont’d.) • Spermatogenesis • Four cells produced • Develop into sperm • Oogenesis • Four cells produced • Only one becomes functional egg

36. Animation – Cancer Metastasizing • Refer to the Common Disease, Disorder or Condition box on Cancer in your textbook and read about the growth of cancer cells. Now watch the 3-D Cancer Metastasizing animation. Click Here to Play Cancer Metastasizing Animation

37. Summary • Discussed how glucose is converted into ATP in the presence of oxygen • Discussed how glucose is converted into ATP in the absence of oxygen • Described how fats and proteins are converted into ATP • Discussed the cell cycle