• Chapter 8: Cell Cycle (Mitosis)

- Background

- Stages of mitosis

- Regulation of cell cycle / cancer

• Chapter 8 cont: Cellular Basis of

Reproduction (Meiosis)

- How is variability introduced?

- If time: Mutations

Chapter 8: The Cell Cycle

Cell Division: Mitosis and Meiosis

• Mitosis – Nucleus of a cell divides to

create 2 new nuclei, each containing an

identical copy of DNA

• Meiosis – Nucleus of a cell divides to

create 4 new nuclei, each with half the

DNA of the original cell

Back to cell theory…

• Cells are fundamental unit of life

• Cells only come from pre-existing cells by

division

Fig 8.2a, pg 127

• Chromatin = DNA

and associated

proteins

(“unwound”)

Chromosome Duplication

Fig 8.3b, pg 128

Cell Cycle

• Interphase =

Growing phase

• Mitotic Phase

= Cell division

Fig 8.4, pg 129

Mitotic Phase (Mitosis): 5 Stages

(Interphase); 1) Prophase, 2) Prometaphase,

3) Metaphase, 4) Anaphase, 5) Telophase

(Cytokenisis)

Fig 8.5, pg 130-131

Interphase

Mitosis: Prophase

Mitosis: Prometaphase

Mitosis: Metaphase

Mitosis: Anaphase

Mitosis: Telophase & Cytokinesis

Cytokinesis in Animal Cells

Fig 8.6a, pg 132

Cytokinesis in Plant Cells

Fig 8.6b, pg 132

Why Does Mitosis Occur?

• Growth

• Cell Replacement

• Asexual Reproduction

Factors Affecting Cell Division

• Anchorage

• Cell Density

• Growth Factors

Cancer: A Disease of the Cell Cycle

Breast Cancer Cell

• Cancer cells do not exhibit anchorage dependence or density-dependent inhibition

AND they can make their own growth factors!

1 2

3 4 5

Meiosis & Genetic Variation

Homologous Chromosomes: Chromosomes that carry genes controlling the

same inherited characteristic – a matched pair

Fig 8.11, pg 136

Sex Chromosomes & Autosomes

• Diploid = cell with two homologous sets of chromosomes

• Haploid = cell with single set of chromosomes (gametes)

Fig 8.12a, pg 137

Meiosis: Two cell divisions

Fig 8.12b, pg 137

Meiosis I

Fig 8.13, pg 138

Prophase I: Crossing Over

Meiosis I cont: Telophase I &

Cytokinesis

Fig 8.13, pg 138

Meiosis II: Starts with 2 haploid cells

Fig 8.13, pg 139

Meiosis and Genetic Variability:

Crossing Over

Meiosis and Genetic Variability: Independent

Assortment

Fig 8.15, pg 141

Meiosis and Genetic Variability:

Random Fertilization

Karyotype • An ordered display of magnified images of

an individual’s chromosomes

Trisomy 21: Down syndrome

Fig 9.12, pg 186 Fig 8.19a, pg 145

Nondisjunction During Meiosis

Fig 8.20, pg 146

Klinefelter Syndrome

Turner Syndrome

Fig 8.23a, pg 148

Alterations of Chromosome

Structure

Fig 8.23b, pg 148

Translocation of Somatic Cells:

Chronic Myelogenous Leukemia (CML)