Aim: What are the major changes in the nucleus during cell division?

Mitosis in a single celled organism

• This type of reproduction involves no exchange of genetic material, and is a type of asexual reproduction. This form of asexual reproduction is often called 'fission'

Mitosis in multi-cellular organisms occurs for

• Growth • Repair

Asexual ReproductionBudding

• Although capable of sexual reproduction, hydras reproduce most of the year by producing external asexual buds that eventually pinch off at the base and become new individuals. 

Budding Hydra

Asexual Reproduction in Plants

Underground stems

• rhizomes • bulbs • corms and • tubers

Asexual Reproduction in Plants

• Bulbs and Tubers

Mitosis also occurs during early embryonic development

• Fertilized egg • Fetus

Cell division involves the process of Mitosis

Step 1

(S phase of Cell Cycle)

Chromosomes Duplicate

Chromosomes make more of themselves

Cell Division• Step 3 Metaphase

Chromosomes line up in the middle of the cell

Cell Division• Step 4 Anaphase

Double stranded chromosomes pull away from each other

Animal Cell

Plant Cell

Step 5 of Cell Division is Cytokinesis

Animal Cell Plant Cell

Cancer developsdue to the loss of growth control in cells

during cell division.

Stages of tumor development

A B Hyperplasia

C

Dysplasia

D in situ cancer malignant

Aim: What controls the cell cycle?

Readings on Enzymes• You will read one article from the folder

• What is its function?

• How can cancer develop when this regulation is disrupted?

Ras Proteins

• Ras protein initiates the cell cycle by stimulating the cell cycle into the S phase and then it stops and waits for another signal to continue

• A mutation in the ras gene causes the cell to keep the cell cycle running with no checks and balances

P53 Tumor Supressor

• Binds to DNA and prevents replication

• More than half of human cancers involve mutations in the P53 protein

Nibrin and ATM

• Repairs chromosomal damages before Mitosis takes place

• A mutation in this protein allows the cell to move onto mitosis with the damaged chromosomes

MAD 1

• The spindle checkpoint prevents anaphase from occurring until chromosomes have attached to the spindle fibers.

• Mutation of this protein causes abnormal chromosome numbers in cancer cells.

• Some forms of chemotherapy prevent spindle formation.