cellular metabolism and reproduction: mitosis and meiosis

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

CELLULAR METABOLISM AND

REPRODUCTION: MITOSIS AND MEIOSIS

Chapter 4

© 2012 Delmar Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

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– 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– Four cells produced– 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

cellular metabolism and reproduction: mitosis and meiosis

Documents