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

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. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Feedback Mechanisms

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. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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. ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Cellular Metabolism or Respiration

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Glycolysis Breakdown of glucose Anaerobic or aerobic process Final outcome 2 pyruvic acid molecules, 2 ATP molecules (anaerobic) ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

The Electron Transport System Series of reduction/oxidation reactions Requires O2 Electron carriers Produces 34 ATP molecules Water is a waste product ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Summary of ATP Production Glycolysis - 2 ATP Krebs cycle – 2 ATP Electron Transport Chain- 34 ATP Therefore…1 glucose molecule yields 38 ATP ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Anaerobic Respiration Fermentation 2 ATP, CO2, ethyl alcohol Muscle fatigue 2 ATP, pyruvic acid converted to lactic acid ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Cellular Reproduction Process of cell duplicatoin Mitosis - duplication of genetic material Cytokinesis - duplication of organelles Meiosis - reduction division only in gonads ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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) ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Interphase / Mitosis / Cytokinesis The Cell Cycle Interphase / Mitosis / Cytokinesis ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Interphase Time between divisions G1 - primary growth phase S - DNA duplication G2 - centrioles complete duplication, mitochondria replicate, chromosomes condense and coil ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Mitosis- Metaphase Chromatids align at equator of cell Centromere divides ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Mitosis- Anaphase Divided centromere pulls chromatids to opposite pole Cytokinesis begins ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Mitosis- Telophase Chromosomes uncoil and decondense Spindle apparatus breaks down New nuclear membrane forms Cytokinesis nearly complete ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Meiosis

Meiosis: A Reduction Division Occurs only in the gonads Reduces genetic material from diploid to haploid Two divisions resulting in four cells ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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 ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Gametogenesis: The Formation of the Sex Cells Spermatogenesis four cells produced develop into sperm Oogenesis four cells produced only one becomes functional egg ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

Comparison of Mitosis and Meiosis ©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.