QOD How many chromosomes do you have Identify

QOD How many chromosomes do you have? Identify them. How many from your father? Mother?

Chapter 8: Cell Reproduction Section 8 -1: Chromosomes

Chromosome Structure To return to the chapter summary click escape or close this document.

Chromosome Structure u Chromosomes = DNA + Proteins u Levels of organization: – DNA – Nucleosome = DNA + Histones – Coils – Supercoils – Chromosome

Chapter 8 Section 1 Chromosomes Chromosome Structure

Chromosome To return to the chapter summary click escape or close this document.

Chromosomes u Before Cell Division – Chromatin – Thinned out u During Cell Division – Thickened – Chromosomes u Chromatids u Centromere (2)

Chromosome Types and Numbers u Types: – Sex chromosomes – Autosomes – Homologous chromosomes – Karyotype u Numbers: – Diploid (2 n) – Haploid (n)

Karyotype

Karyotype

QOD How many chromosomes does a skin cells have after it divides by mitosis? What happens to ensure this number is achieved? When?

Chapter 8: Cell Reproduction Section 8 -2: Cell Division

Cell Division u In Prokaryotes – Binary fission u In Eukaryotes – Mitosis – Meoisis

Chapter 8 Section 2 Cell Division in Prokaryotes

QOD Define mitosis. What is the end result of mitosis?

Stages of Cell Cycle To return to the chapter summary click escape or close this document.

III. The Cell Cycle u Interphase – G 1 –S – G 2 u. M Phase – Mitosis – Cytokinesis

The M phase u Mitosis – Division of the nucleus – Prophase – Metaphase – Anaphase – Telophase u Cytokinesis cytoplasm – Division of the

Mitosis

Animal cell undergoing mitosis To return to the chapter summary click escape or close this document.

Prophase u Nucleus disappears u Centrosomes/Centrioles move u Spindle fibers form – mitotic spindle – Kinetochore fibers/ Kinetochore – Polar fibers

Mitosis continues u Metaphase – Metaphase plate u Anaphase – Role of kinetochore u Telophase – Reversal of prophase – Results:

QOD How does the cell control the cell cycle? What happens when control is lost?

Animal cell undergoing mitosis To return to the chapter summary click escape or close this document.

Plant Cell Undergoing Mitosis To return to the chapter summary click escape or close this document.

Cytokinesis u Division of the cytoplasm u Separates two nuclei into two distinct daughter cells u Animal cells – cleavage u Plant cells – form cell plate

Control of Cell Division u Checkpoints: – G 1 – G 2 – Mitosis u Loss of control – Cancer

QOD Compare and contrast mitosis to meiosis

Chapter 8: Cell Reproduction Section 8 -3: Meiosis

Homologous Chromosome To return to the chapter summary click escape or close this document.

Meiosis u “Reduction” division u Produces gametes u 2 divisions u Diploid haploid u Fertilaztion – n + n = 2 n

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Meiosis I u Prophase I – Much of it same as prophase in mitosis u Nucleus/nucleolus disappears u Chromosomes coil u Centrioles and spindle fibers – Homologous chromosomes pair up u Synapsis u Forms a tetrad u Crossing-over genetic recombination

Crossing Over Diagram To return to the chapter summary click escape or close this document.

QOD What is independent assortment?

Meiosis I u Metaphase I – Tetrads line up u Anaphase I – Independent assortment genetic variation u Telophase I – Cytokinesis begins – Forms 2 haploid cells

LE 13 -8 ab MEIOSIS I: Separates homologous chromosomes METAPHASE I PROPHASE I ANAPHASE I Sister chromatids remain attached Centromere (with kinetochore) Sister chromatids Chiasmata Metaphase plate Spindle Tetrad Homologous chromosomes (red and blue) pair and exchange segments; 2 n = 6 in this example Microtubule attached to kinetochore Tetrads line up Homologous chromosomes separate Pairs of homologous chromosomes split up

Meiosis II u No copying of DNA u Follows process of mitosis u Prophase II u Metaphase II u Anaphase II u Telophase II u Cytokinesis

LE 13 -8 b MEIOSIS II: Separates sister chromatids TELOPHASE I AND CYTOKINESIS PROPHASE II Cleavage furrow Two haploid cells form; chromosomes are still double METAPHASE II ANAPHASE II Sister chromatids separate TELOPHASE II AND CYTOKINESIS Haploid daughter cells forming During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing single chromosomes

Results u Gametes – 4 haploid cells – Genetically different u Males: – Spermatogensis u Females: – Oogenesis – 1 egg cell, 3 polar bodies

Chapter 8 Section 3 Meiosis in Male and Female Animals