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

3. 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

4. Cellular Metabolism or Biochemical Respiration

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

6. 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)

7. 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

8. 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

9. Anaerobic Respiration

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

11. 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

12. Production of ATP from General Food Compounds

13. 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

14. 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

15. Introduction to Cellular Reproduction

16. 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

17. The Structure of the DNA Molecule

18. 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

19. 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

20. 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

21. The Cell Cycle

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

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

24. 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

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

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

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

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

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

30. Meiosis: A Reduction Division

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

32. 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

33. 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

34. 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

35. Gametogenesis: The Formation of the Sex Cells

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

37. 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

38. 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