Chapter 6 Cell Reproduction Two Types of Reproduction

Chapter 6: Cell Reproduction • Two Types of Reproduction a. Sexual – create genetic diversity (offspring not identical to parents) b. Asexual – offspring is identical to parent.

Binary Fission • Asexual reproduction • Takes place in prokaryotic cells • 2 stages: – DNA is copied – Cell pinches apart into two identical cells

6 -1 chromosomes • Eukaryotic cells form 1. DNA copied 2. Chromatids form (exact copies of DNA) Centromere – hooks chromatids together

Chromosome number • Homologous chromosomes – similar is size, shape, genetic content. – Diploid cell – two sets of chromosomes ( one from each parent) – Haploid cell – one set of chromosomes (sex cells)

Human Chromosome # • Humans – 46 chromosomes – 23 from Mom – 23 from Dad • Sex Chromosomes – determine sex XX – female, XY - male

Somatic cells vs Gamates • Somatic cells body cells (liver, skin) • Diploid (46) • Gamate cells – sperm or egg cells • Haploid (23) • Zygote – two gamates fuse

Edwards syndrome

Down’s Syndrome

Chromosome Abnormalities

1. Inversion • Inversion – a piece of chromosome breaks off and rejoins in the reverse • ABCDEF (normal chromosome) • ACBDEF (inversion)

2. Translocation • Translocation – a piece of chromosome breaks off and attaches to another chromosome

Translocation

3. Deletion – Part of a chromosome breaks off and is lost. • Normal – 1234567 • Deletion – 12567 Cri du chat is a rare syndrome (1 in 50, 000 live births) caused by a deletion on the short arm of chromosome 5

Cri du Chat Karyotype

4. Nondisjuction • One or more chromosomes fail to separate –Trisomy – gamate has one extra chromosome –Monosomy – gamate is missing a chromosome

Nondisjuction • Trisomy • http: //learn. genet ics. utah. edu/con tent/begin/traits/ predictdisorder/i ndex. html

Nondisjuction • Monosomy • Turners Syndrome – female with a missing X chromosome

Cell Cycle – cells lifespan http: //www. phsuccessnet. com/i. Text/produc ts/0 -13 -115075 -8/index. html

Cell Cycle Steps • G 1 Phase – rapid growth • S phase – DNA copied (chromatids) • G 2 phase – prepare to divide • Mitosis- nucleus divides • Cytokinesis- cytoplasm divides • IPMAT c

Importance? ? ? • • Growth Replacement Cancer Regeneration of…

Cancer? • Unregulated mitosis • How does it begin?

Mitosis – • division of nucleus • 4 Stages of : 1. 2. 3. 4. Prophase Metaphase Anaphase Telophase

Prophase • Chromosomes thicken • Nuclear membreane breaks down • Nuclelous issapears • Spindle fibers formed • Centrioles appear

metaphase • Each chromosome lines up midway between poles

Anaphase • Centromeres divide • 2 chromatids separate • chromosomes pulled to the opposite ends of the cell

Telephase • Chromosomes arrive at opposite poles • Spindle fibers disappear • Nuclear membrane reappears • Chromosomes uncoil (lighten)

Cytokinesis • Division of the cytoplasm • Result – 2 Identical cells

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis

Name stage of mitosis