CELL CYCLEOver time, many cells die and need to be replaced. • Mitosis - The process by which a cell reproduces to

create two identical cells. • Daughter Cells - Two identical cells formed by

mitosis• Cell Cycle – 4 different stages of the cell’s life leading

to division into new daughter cells.– G1, S, G2, M

• Many of the abnormal traits of cancer cells are due to defects in genes that control cell division.

Cell Cycle

• The cell cycle consists of four stages G1, S, G2, and M.

• G1 and G2 are 'gap' phases in which the cell grows and prepares to divide.

• S in the synthesis phase in which the chromatin (DNA) is copied (replicated).

• M is the mitotic phase in which the cell physically divides into two daughter cells.

• Most cells are NOT actively dividing. These cells are in a resting state (G).

• Mitosis is a process where cells are produced for growth and/or replacing damaged or old cells

• Mitosis in normal cells produces two cells with identical genetic content.

• Mitosis has four sub-phases:

PROPHASE• Chromosomes condense, the nuclear membrane

breaks down, and spindle fibers form

METAPHASE

• The replicated chromosomes line up in the middle of the cell

ANAPHASE• Chromosomes separate and the cell becomes

elongated, with distinct ends (poles)

TELOPHASE

• Nuclear envelopes re-form at the two poles and new cell membranes begin to form to create two independent cells

CYTOKINESISthe division of the cytoplasm to make two complete daughter cells

• ANIMAL CELLS– Cell membrane pinches apart

into two equal parts with one nucleus in each daughter cell

• PLANT CELLS– Cell plate forms between two

nuclei– Cell plate develops into a cell

wall

Animations

http://www.johnkyrk.com/mitosis.html

http://www.hybridmedicalanimation.com/anim_mitosis.html

Activity

• Each person will need one sheet of paper. – Name, block and date at the top right.– Title: Mitosis Quiz

I will show each slide in turn. Number your answers according to the

numbered picture/word.Do not forget to label identifying marks on

pictures.

CYTOKINESIS1.

2.

3.

METAPHASE4.

5.

6.

PROPHASE7.

8.

ANAPHASE9.

10.