Cell Cycle REVIEW

aka.. The story of the life of a cell.

What phase does a cell spend most of its time in? Interphase– subphase=G1

What happens in G1?

The cell is metabolically active=

Performing the chemical reactions needed for the cell to do all the jobs in needs to do

In G1, What is DNA called and what does it look like? Chromatin

A thin, tangled mass (good for directing protein making to catalyze chemical rxns).

What is the G1 checkpoint checking for:

Is the cell healthy enough and large enough to divide?

What happens in S phase?

Synthesis of, Replication of, Duplication of:

DNA

Need two copies of the DNA if the cell is going to divide and make two identical cells from the original

What happens in G2?

The DNA coils and condenses.

Each strand joins to its duplicate at the centromere- now called duplicated chromosome made of two sister chromatids.

Centriole is duplicated, too What does the G2 checkpoint check for?

It checks the DNA to make sure it was copied accurately. If not, repairs can be made or cell can die.

Now for Mitosis!

What will divide in Mitosis?

The Nucleus!

How many subphases are there in Mitosis?

4= PMAT

Prophase, Metaphase, Anaphase, Telophase

Describe Prophase.

Nuclear membrane dissolves

Centrioles move to opposite poles

Spindle fibers attach to chromosomes

What happens in Metaphase?

Spindles move the duplicated chromosomes to the equator (midline)

They line up head to toe in a row

Anaphase

Duplicated chromosomes are pulled apart

They are now unduplicated

They move to opposite sides (poles)

Telophase- the last phase of Mitosis

Two nuclei form

The membranes around them form

Spindles break down

Cytokinesis

The cytoplasm is divided and the two separate cells form. They are identical.

In plant cells, a cell plate forms (see above)

In animal cells, the cytoplasm pinches or furrows in (see right).

Identify the following: chromosomes, chromatids, centromere, centriole, spindle

What does the DNA instruct the cell to make? Protein

Specifically, enzymes that:

Catayze reactions including the process of cell division

Types of DNA (genes) that start or stop cell division: Proto-onco genes= accelerator- they tell the

cell to go ahead and divide (reproduce)

Tumor suppressor genes= brakes that stop the process of cell division

What is contact inhibition?

Under normal DNA instructions, contact inhibition stops a cell from dividing when it is touching other cells.

But sometimes, things go terribly wrong!

Mutations- What are they?

Changes in DNA caused by:

Mutagens- factors in the environment- chemicals (tobacco, drugs, cleaning products,

pesticides), energy (radiation, x-rays)

Random mistakes in DNA copied or inherited

These can cause cancer, AKA

Uncontrolled cell growth= the cells divide because there are failures in tumor suppressor and proto-onco genes

The cell is in contact with other cells, but proto-onco genes are turned on and the suppressor genes are turned off.

How is cancer treated?

1. Surgery– remove the tumor or group of cells that is dividing rapidly

2. radiation- using concentrated radiation to kill cancer cells

3. chemotherapy- chemicals (powerful drugs) that kill cancer cells

The End

Good luck!