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

2. Standard 5
Explain how organisms use positive and negative feedback mechanisms to maintain their internal environment and respond to external environmental changes. Identify possible consequences that can occur if the body does not maintain homeostasis. Summarize how cellular metabolism can affect the body’s homeostatic state.
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3. Feedback Mechanisms

4. Introduction Positive and Negative Feedback
What is the difference between positive and negative feedback?
Many molecular and physiological processes are controlled by feedback mechanisms. In a feedback loop the product of a process, such as the breakdown of proteins into amino acids, has an effect on the rate of the process.
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5. Negative Feedback
Negative feedback occurs when the rate of the process decreases as the concentration of the product increases.
Negative feedback controls the rate of a process to avoid accumulation of a product.
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6. Positive Feedback
Positive feedback occurs when the rate of a process increases as the concentration of the product increases.
The rate of a process will continuously accelerate under positive feedback as long as substrate is available and the product is not consumed by some other process.
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7. Cellular Metabolism or Respiration

8. 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
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9. Glycolysis Breakdown of glucose Anaerobic or aerobic process
Final outcome
2 pyruvic acid molecules, 2 ATP molecules (anaerobic)
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10. The Krebs Citric Acid Cycle
Pyruvic Acid > Acetic Acid > Acetyl-CoA
Acetyle-CoA enters Krebs cycle in mitochondria
Final outcome
6 CO2, 10 NADH, 2 FADH2, 2 ATP
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11. The Electron Transport System
Series of reduction/oxidation reactions
Requires O2
Electron carriers
Produces 34 ATP molecules
Water is a waste product
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12. Summary of ATP Production
Glycolysis - 2 ATP
Krebs cycle – 2 ATP
Electron Transport Chain- 34 ATP
Therefore…1 glucose molecule yields 38 ATP
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13. Anaerobic Respiration
Fermentation
2 ATP, CO2, ethyl alcohol
Muscle fatigue
2 ATP, pyruvic acid converted to lactic acid
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14. Production of ATP from General Food Compounds
Glycolysis, Krebs /citric acid cycle, and electron transport
Carbohydrates provide glucose for glycolysis
Fats digested into glycerol
Proteins digested into amino acids
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15. Cellular Reproduction
Process of cell duplicatoin
Mitosis - duplication of genetic material
Cytokinesis - duplication of organelles
Meiosis - reduction division only in gonads
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16. 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)
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17. Interphase / Mitosis / Cytokinesis
The Cell Cycle
Interphase / Mitosis /
Cytokinesis
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18. Interphase Time between divisions G1 - primary growth phase
S - DNA duplication
G2 - centrioles complete duplication, mitochondria replicate, chromosomes condense and coil
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19. Mitosis- Prophase
Chromosomes become visible as chromatids joined by certromere
Two kinetochores at the centromere
Centrioles move to opposite poles
Nuclear membrane breaks down
Microtubules attach kinetochores to spindle
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20. Mitosis- Metaphase Chromatids align at equator of cell
Centromere divides
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21. Mitosis- Anaphase Divided centromere pulls chromatids to opposite pole
Cytokinesis begins
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22. Mitosis- Telophase Chromosomes uncoil and decondense
Spindle apparatus breaks down
New nuclear membrane forms
Cytokinesis nearly complete
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23. 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
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24. Meiosis

25. Meiosis: A Reduction Division
Occurs only in the gonads
Reduces genetic material from diploid to haploid
Two divisions resulting in four cells
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26. Stages of Meiosis(I)
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
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27. Stages of Meiosis (II)
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
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28. Gametogenesis: The Formation of the Sex Cells
Spermatogenesis
four cells produced develop into sperm
Oogenesis
four cells produced only one becomes functional egg
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29. Comparison of Mitosis and Meiosis
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