Chapters 10 and 11:Cell Growth and Division

Mitosis/Meiosis/Cancer

Why is it necessary for cells to divide? DNA Overload-not enough information for

the cell as it grows larger in size To improve material exchange Volume of cell increases faster than surface

area

What is Cell Division ?

process where a cell divides into two new daughter cells Before cell division takes place, the cell must

copy or replicate its DNA. Each daughter cells gets a complete copy of the

original DNA Cell division has 2 parts

Mitosis: division of nucleus and DNA Cytokinesis: division of cytoplasm and organelles

Chromosomes- condensed form of DNA

Sister chromatids- 1 chromosome and a copy of it “tied” together before the cell divides

Centromere- the chemical “knot” holding sister chromatids together

LABEL THE DIAGRAM IN YOUR NOTES.

Figure 10–4 The Cell Cycle

M phase

G2 phase

S phase

G1 phase

Figure 10–4 The Cell Cycle

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Figure 10–5 Mitosis and Cytokinesis

Prophase-Phase #1 of Mitosis

Longest Phase-50% to 60% of total time to complete mitosis

Chromatin condenses into Chromosomes Centromeres connect sister chromatids Centrioles separate to opposite poles Spindle is organized Nucleolus disappears and nuclear envelope

breaks down.

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Figure 10–5 Mitosis and Cytokinesis

Metaphase-Phase #2 of Mitosis

Centromeres attach to spindle fibers Chromosomes line up across the equator of

the cell-metaphase plate

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Figure 10–5 Mitosis and Cytokinesis

Anaphase-Phase #3 of Mitosis

Sister chromatids separate becoming individual chromosomes and moving to opposite poles of cell

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Figure 10–5 Mitosis and Cytokinesis

Telophase-Phase #4 of Mitosis

Chromosomes disperse into chromatin Nuclear envelope re-forms around each

cluster of chromatin Spindle breaks apart Nucleolus visible in each new daughter

cell

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Figure 10–5 Mitosis and Cytokinesis

Cytokinesis

Division of cytoplasm and organelles Animal Cells: Cleavage Furrow-cell

membrane pinches inward Plant Cells: Cell Plate-develops into

separating membrane (cell wall appears shortly after)

Centrioles

Chromatin

Interphase

Nuclear envelope

Cytokinesis

Nuclear envelope reforming

Telophase

Anaphase

Individual chromosomes

Metaphase

Centriole

Spindle

CentrioleChromosomes

(paired chromatids)

Prophase

Centromere

Spindle forming

Figure 10–5 Mitosis and Cytokinesis

Cytokinesis

Prophase

Interphase

Metaphase

Prophase

Anaphase

Telophase

Cancer

Disorder in which some cells lose ability to control growth

Form tumors Carcinogen- cancer causing agent (ex.

Cigarettes, UV radiation from sun)

Regulating the Cell Cycle

Skin Cancer : Melanoma

Asymmetrical, Borders, Color, Diameter, Elevation

Meiosis

Cell Division to produce gametes-sex cells (sperm and egg)

Number of chromosomes per cell is cut in half through separation of homologous chromosomes in diploid cell

Homologous Chromosomes

Chromosomes containing same genes 1 chromosome from mom and 1 chromosome

from dad Diploid=2N-cell that has both copies meaning 2

complete sets of genes/chromosomes (all regular cells-somatic cells) In humans 2n=46

Haploid=N-cell that has one set/copy (gametes/sex cells) In humans n=23

Crossing over occurs during Prophase I, and homologous chromosomes exchange portions of their chromatids (DNA)

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Gamete Formation

In males4 sperm cells are produced In females1 egg cell is produced

Other 3 cells=polar bodies-not involved in reproduction and eventually degenerate b/c do not receive enough cytoplasm containing nutrients

Mitosis Meiosis

Results in production of 2 genetically identical diploid cells

Creates all cells in the body EXCEPT gametes

PMAT

Results in production of 4 genetically different haploid cells

Creates gametes Reason why everyone is

slightly different EXCEPT for identical twins/triplets

PMAT x2 Tetrads form and crossing

over happens