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

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

Cellular Metabolism or Biochemical Respiration

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

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)

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

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

Anaerobic Respiration

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

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

Production of ATP from General Food Compounds

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

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

Introduction to Cellular Reproduction

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

The Structure of the DNA Molecule

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

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

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

The Cell Cycle

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

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

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

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

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

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

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

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

Meiosis: A Reduction Division

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

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

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

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

Gametogenesis: The Formation of the Sex Cells

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

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

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