Mitosis (Cell Division)

MITOSIS

Vocab1. Cell Cycle: the life cycle of a eukaryotic

cell, consisting of growth and division

2. Chromatin: uncoiled DNA

3. Chromosomes: coiled DNA and protein

Chromatin

4. Chromatids: identical chromosome copies, ½ of the X shape chromosome

5. Centromere: holds the chromatids together

ChromosomeChromatid

Centromere

Vocab cont.

6. Homologous Chromosomes: a pair of chromosomes with matching information

7. Cytokinesis: when the cytoplasm divides after mitosis

Limits to Cell Growth:

1. DNA Overload:- DNA would not be able to instruct all of the activities going on in the cell

2. Exchanging Materials:- As the cell size increases it would be more difficult for a larger cell to get oxygen and nutrients in and wastes out

Cell Division

• process by which a cell divides and produces 2 IDENTICAL daughter cells

• Why do cells divide?

1) Growth of the organism

2) Repair damaged cells

3) Reproduction

The Steps of the Cell Cycle:

• 4 phases:

1. G1: cell growth

The Steps of the Cell Cycle:

• 4 phases:

1. G1: cell growth

2. S: DNA

replication

The Steps of the Cell Cycle:

• 4 phases:

1. G1: cell growth

2. S: DNA

replication

3. G2: cell growth

The Steps of the Cell Cycle:

• 4 phases:

1. G1: cell growth

2. S: DNA

replication

3. G2: cell growth

4. Mitosis: cell

division

(P, M, A, T)

Interphase

- this is the longest

phase of the cell

cycle and includes the G1, S,

and G2 phaseschromatin:(DNA)

Nucleolus

Nuclear

Membrane

Cell

Membrane

Mitosis

• Cell Division of body cells

• Shortest phase of the Cell Cycle

• Consists of 4 phases1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

Mitosis Step 1: Prophase

- DNA coils up into

chromosomes, with 2

copies of each chromosome (sister chromatids) held together by a centromere

Mitosis Step 1: Prophase cont.

- Nucleolus and Nuclear Mem. disappear

- Spindle fibers form

Spindle Fibers

Chromosomes

Mitosis Step 2: Metaphase

- Chromosomes attach to spindle fibers by centromeres and line up across the middle

Spindle Fibers

2nd chromatid

One chromatid

Centromere

Mitosis Step 3: Anaphase

- Centromeres split apart

- Sister chromatids are pulled to opposite

ends of the cell by the spindle fibers

Spindle Fibers

Centromere

One chromatid

2nd chromatid

Mitosis Step 4: Telophase

• Chromatids reach opposite ends of the cell

• Nucleolus and Nuclear Membrane reappears

Mitosis Step 4: Telophase

- Cell membrane begins to separate

- Cytokinesis occurs:

division of cytoplasm

- animal cells: cleavage furrow

- plant cells:

cell plate

Cleavage Furrow

(Animal cell only)

The Result:

• 2 new identical daughter cells, the old cell no longer exists

Animal Cell Mitosis

Plants

Cell Plate