I. MitosisHappy Halloween!

Why do animals shed their skin?

A. Asexual Reproduction

1. When do cells use it?

a) Growthb) Repairc) Replacement

2. Cell that reproduce by asexual reproduction reproduce constantly.

B. Mitosis = Asexual Reproduction

1. Division of somatic cells (body)2. Process in which the nucleusdivides to form 2 new nuclei

Somatic Cell

Daughter Cells

Performed by a single (parent) cell

C. PURPOSE OF MITOSIS:

a. EXACTLY THE SAME KIND OF CHROMOSOMES

OF CHROMOSOMES.b. EXACTLY THE SAME NUMBER

1. TO PRODUCE TWO NEW NUCLEI WITH…

D. What are Chromosomes?

1. Organized structure of DNA in the cell

2. Located in the nucleus3. Usually are uncoiled in

the form of chromatin4. Only visible when the

cell divides and the chromatin condenses

5. Held together by a centromere

E. 5 Stages of the Cell Cycle(do not write)

InterphaseProphaseMetaphaseAnaphaseTelophase

**Animated Video**

1. Interphasea) Prior & After Mitosisb) G1 period

i. 90% of cell life spent here

ii. Cell goes about it’s business

c) S periodi. DNA is duplicated

d) G2 periodi. Cell prepares to divide

e) Cannot see DNA- uncoiled as chromatin

2. Prophase

a) DNA becomes visible as chromosomes

b) Nuclear membrane dissolves

c) Centrioles migrate to opposite poles

d) Spindle fibers form

Easy to remember- Prophase- prepares for mitosis

3. Metaphasea) Spindle fibers attach to

centromeresb) Chromosomes line up

at midline of the cell

Easy to remember- metaphase, DNA at middle

Spindle Equator

Pole

Pole

4. Anaphase

a) Spindle fibers pull apart centromeres

b) One chromatid goes to each centriole (they look like V’s)

Easy to remember- anaphase, away they go

5. Telophase

a) Chromatids reach centrioles

b) Mitosis ends when new nuclear membranes form

c) Some evidence of cell dividing

Easy to remember- telophase, terminal phase

6. Last part- Cytokinesis

a) Division of Cytoplasmb) Technically not in mitosis

i. Animal cell- pinching of cell membrane- cleavage

ii. Plant cell- formation of new cell wall- cell plate

iii. DNA becomes non-visible, back to chromatin

c) Daughter cells enter G1 period of interphase

The Cycle Just Keeps Going!

What Kind of Cells Does Mitosis Produce?

• Cells with a complete set of chromosomes called diploids

• Humans have 46 chromosomes or 23 pairs of chromosomes

• Human diploid # = 23• Most cells are diploid

Cancer

• Uncontrollable mitosis (no G1)– Cells cease to do what

they are supposed to be doing in favor of dividing.

• Cancer does not “poison” your body…

Henrietta Lacks• 1951, a poor 31 Year old African

American mother of 4 was dying of cervical cancer @ Johns Hopkins Hospital– Dr. George Gey- sampled some of the

cancerous cells, found they could live indefinitely and multiply outside the body

– She died 6 months later, but cells still live on

• HeLa cells– Used to study many different diseases– Polio Vaccine– How to transport cells

The Mitosis Shuffle!

• First, lets watch:University of Madison Mitosis Shuffle

• Your turn!“The Hustle” by Van McCoy

Homework• Mitosis Booklet – 3 pgs– 5 phases– 6 colors (one per chromosome)