Cell CycleCell Cycle and andCell Division Cell Division

BIG PICTUREBIG PICTURE

Mitosis

One (Diploid) Cell becomes Two (Diploid) Cells

Example : Cats Somatic Cells have 38 (2n) chromosomes

Sex cells have 19 (n) chromosomes

2n

2n2n

ChromosomesChromosomes

Chromosome(unduplicated)

Chromosome(duplicated)

DNA ReplicationCentromere

ArmGenes/DNA

2 sister chromatids

• Contain the genetic information• How this information is transmitted from one cell to

another

A Chromosome

Number of ChromosomesNumber of Chromosomes

Types of Chromosomes (Humans)

1. Body (Autosomes) – 44 chromosomes (22 pairs)

2. Sex – 2 chromosomes (1 pair) (females XX, males XY)

Total Number of Chromosomes = 46

To Begin - Terminology

• Somatic cell – A body cell (muscle, skin, etc)• Cytokinesis – the cytoplasm of one cell is divided evenly into

the two daughter cells

• Sister Chromatids

The End Result

Two cells are created with the same genetic information and number of chromosomes as their parent cell.

• http://www.johnkyrk.com/mitosis.html - *

• http://www.unitedstreaming.com/search/assetDetail.cfm?guidAssetID=9B385B50-541B-447A-89CF-2016A3CFC094

Where does Mitosis occur?

• Only occurs in somatic cells (ex. muscle, skin)

• Produces diploid somatic cells

Interphase

During Interphase:

• Growth -> Duplication of chromosomes -> Growth

• Takes in nutrients to build proteins

• Duplicates chromosomes within the nucleus to create sister chromatids (joined by the centromere)

Homologous Pairs

Prophase

• Individual chromosomes shorten and thicken

• Strengthens DNA for Mitosis

Metaphase

• Sister chromatids line up along the middle of the cell

Anaphase

• The sister chromatids split to form two individual chromosomes

• The two individual chromosomes move to opposite ends of the cell

Telophase

• Chromosomes reach the ends of the cell

• Nuclear membrane begins forming

• Cytokinesis occurs resulting in two daughter cells each containing all cell organelles and 2n chromosomes

• Interphase begins again

Telophase

Make A Chart• List IPMAT down the left side (below each phase

list how to remember it!)• Across the top, put:

– Genetic Information– Centrioles– Spindle Fibres– Nuclear membrane– Drawing (place a rough labelled sketch in here)

• Describe how each of the cell parts involved are behaving in each stage

Cell CycleCell CycleTwo main phases:1. Interphase

3 stages• G1 – rapid growth• S – DNA replication• G2 – prepare for mitosis

2. Mitosis (M) = division of the nucleus4 stages

• Prophase• Metaphase• Anaphase• Telophase

3. Cytokinesis = Division of the cytoplasm

MitosisMitosisInterphaseInterphase

AnaphaseAnaphase

MetaphaseMetaphase

ProphaseProphase

CytokinesisCytokinesis

TelophaseTelophase

InterphaseInterphase

• Growth• DNA replication• At the end, all chromosome have two sister

chromatids

ProphaseProphase1. Chromosome formation

• DNA condenses• Nuclear membrane dissolves

2. Centrioles move to opposite poles of cell

MetaphaseMetaphase1. Centromere of chromosomes joins to spindle

fiber

2. Chromosomes line up in the middle of the cell

AnaphaseAnaphase1. Centromere doubles

2. Chromatids separate and are pulled to opposite poles by the spindle fibers

TelophaseTelophase1. Nuclear membrane reappears in the two

daughter cells

Cytokinesis – Cytokinesis – separation of cytoplasm; final stage of cell division

Mitosis under the Mitosis under the microscopemicroscope

PROPHASEMETAPHASE ANAPHASE TELOPHASE

Mitosis Lab –Root TipMitosis Lab –Root Tip

MetaphaseMetaphase

TelophaseTelophase

AnaphasAnaphasee

ProphaseProphase

InterphaseInterphase

Vocabulary

The Cell Cycle

Chromosomes

Interphase

Mitosis

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

Homework

Page 44Questions #1 - 7

Mitosis On the Table

• Using pipe cleaners and your text, recreate the stages of mitosis on your desk with a partner

• 1 partner tries each phase, and the other partner checks to make sure it’s done correctly

• Raise your hand for teacher to check

• Then switch roles