Power Point Lecture Presentation for Concepts of Genetics

Power. Point® Lecture Presentation for Concepts of Genetics Ninth Edition Klug, Cummings, Spencer, Palladino Chapter 2 Mitosis and Meiosis Lectures by David Kass with contributions from John C. Osterman. Copyright © 2009©Pearson Education, Inc. Copyright 2009 Pearson Education, Inc.

Copyright © 2009 Pearson Education, Inc. Figure 2. 1

What are the differences between prokaryotic and eukaryotic organisms? Try to come up with 3 Copyright © 2009 Pearson Education, Inc.

Name some of the main representative types of organisms in each group Prokaryotic Copyright © 2009 Pearson Education, Inc. Eukayrotic

Organisms organize DNA in structures called chromosomes. Which is prokaryotic, (a) or (b) (a) A. [Default] B. [MC Any] C. [MC All] Copyright © 2009 Pearson Education, Inc.

Parts of a chromosome Copyright © 2009 Pearson Education, Inc.

The structure labeled 2 is: A. centrosome B. centromere C. centriole Copyright © 2009 Pearson Education, Inc.

The structure labeled: A. p arm B. monad C. q arm Copyright © 2009 Pearson Education, Inc.

Cell Division • Prokaryotes • Binary fission • Eukaryotes • transmission of genetic material from one generation of cells to next involves: • Mitosis +cytokinesis • Meiosis + cytokinesis http: //www. youtube. com/watch? v=m 73 i 1 Zk 8 EA 0 Copyright © 2009 Pearson Education, Inc.

E. coli – Binary Fission Copyright © 2009 Pearson Education, Inc. Figure 2. 2

Section 2. 2 – Homologous Chromosomes • In each homologous pair of chromosomes, one member is derived from each parent. Identify location of: • Sister chromatids • Centromere • Kinetochore • Telomeres Standford. edu. 2010. http: //www. stanford. edu/group/hopes/basics/dna/f_b 11 homolgs. jpg Copyright © 2009 Pearson Education, Inc.

Copyright © 2009 Pearson Education, Inc. Figure 2. 3

Diploid vs Haploid Organisms • Diploid Organisms • 2 copies of each chromosome for most of its life cycle • Haploid Organisms • 1 copy of each chromosome for most of its life cycle • Ex. Bacteria, yeasts and molds, some plants such as bryophytes (mosses) Copyright © 2009 Pearson Education, Inc.

Mechanism of chromosome separation • http: //www. youtube. com/watch? v=YAva 4 g 3 Pk 6 k Copyright © 2009 Pearson Education, Inc.

Use the karyotype to identify sex: A. Female B. Male Copyright © 2009 Pearson Education, Inc.

When Does Mitosis Occur? • Multicellular Organisms • Growth • Tissue repair • Cell replacement of certain tissues (e. g. epidermis – skin) • Single-celled Organisms (prok and euk) • Asexual reproduction Copyright © 2009 Pearson Education, Inc.

Mitosis – two main processes • Karyokinesis • Genetic material is partitioned to daughter cells during nuclear division • Cytokinesis • Cytoplasmic division follows. Copyright © 2009 Pearson Education, Inc.

Cell Cycle Copyright © 2009 Pearson Education, Inc.

Cell Cycle Copyright © 2009 Pearson Education, Inc.

Mitosis • Mitosis has discrete stages: • • • prophase prometaphase anaphase telophase (see Figure 2. 7) http: //www. youtube. com/watch? v=DD 3 IQkn. CEdc Copyright © 2009 Pearson Education, Inc.

Copyright © 2009 Pearson Education, Inc. Figure 2. 7

Cell-Cycle Regulation and Checkpoints Copyright © 2009 Pearson Education, Inc.

Cyclin-dependent Kinases • Cell cycle is driven by enzymes called Cyclin-dependent kinases, or Cdk’s • Kinases are enzymes that phosphorylate (add a phosphate group to) other proteins • stimulates or inhibits protein’s activity • Cdk’s are active only when they bind to other proteins called cyclins Copyright © 2009 Pearson Education, Inc.

Enzymes Drive the Cell Cycle • Cell division occurs when growth factors bind to cell surface receptors, which leads to cyclin synthesis • Cyclins then bind to and activate specific Cdk’s Copyright © 2009 Pearson Education, Inc.

Activated Cdk’s • Promote a variety of cell cycle events – Synthesis and activation of proteins required for DNA synthesis – Chromosome condensation – Nuclear membrane breakdown – Spindle formation – Attachment of chromosomes to spindle – Sister chromatid separation and movement Copyright © 2009 Pearson Education, Inc.

Copyright © 2009 Pearson Education, Inc.

Meiosis • Meiosis reduces the amount of genetic material by one-half to produce haploid gametes or spores containing one member of each homologous pair of chromosomes. Copyright © 2009 Pearson Education, Inc.

Meiosis • Meiosis I and II each have prophase, metaphase, and telophase stages (Figure 2. 10). Copyright © 2009 Pearson Education, Inc.

Meiosis Copyright © 2009 Pearson Education, Inc. Figure 2. 10

Meiosis • Prophase I has five substages, each including specific events (see Figure 2. 9): • • • leptonema zygonema pachynema diplonema diakinesis • At the completion of prophase I, the centromeres of each tetrad structure are present on the equatorial plate. Copyright © 2009 Pearson Education, Inc.

Prophase I Additional Terms to Know: • Synapse • Tetrad • Crossing over Copyright © 2009 Pearson Education, Inc. Figure 2. 9

Meiosis I • Metaphase I, and telophase I are similar to those of mitosis. Copyright © 2009 Pearson Education, Inc.

Meiosis Copyright © 2009 Pearson Education, Inc. Figure 2. 10

Meiosis II • During meiosis II, the sister chromatids in each dyad are separated to opposite poles. • Each haploid daughter cell from meiosis II has one member of each pair of homologous chromosomes. Copyright © 2009 Pearson Education, Inc.

Disjunction and Nonjunction • Disjunction • Separation of homologous chromosomes • Nondisjunction • during meiosis I or II leads to gametes with abnormal numbers of chromosomes and can lead to abnormal offspring. Copyright © 2009 Pearson Education, Inc.

2. 5 The Development of Gametes Varies in Spermatogenesis Compared to Oogenesis Copyright © 2009 Pearson Education, Inc.

Section 2. 5 • Male gametes are produced by spermatogenesis in the testes (Figure 2. 11). • Female gametes are produced by oogenesis in the ovary. Copyright © 2009 Pearson Education, Inc.

Copyright © 2009 Pearson Education, Inc. Figure 2. 11

Importance of Meiosis • Mechanism of meiosis is basis for production of extensive genetic variation. • Gametes receive either the maternal or the paternal chromosome from each homologous pair of chromosomes. • An organism can produce 2 n (where n represents the haploid number) combinations of chromosomes in gametes. Copyright © 2009 Pearson Education, Inc.

Life Cycles Differ in Certain Organisms • Diploid life cycle • Ex. Humans and other animals • Haploid life cycle • Ex. Fungi, protists • Alternation of generation • Plants Copyright © 2009 Pearson Education, Inc.

The End Copyright © 2009 Pearson Education, Inc.