1. 5.1 Cell Cycle and Mitosis
Chapter 5 notes

2. Cell cycle overview

3. Life Cycle of a cell
1. Interphase – longest stage (80% of the time) where the cell carries out its various functions
Growth and preparation – cell increases in size and makes proteins and molecules to function; some organelles duplicate 
replication– DNA copies itself (all 3 billion bases!) Fig 5.5
DNA molecule unwinds and “steps” of ladder break apart (enzymes help out with this)
New bases pair with bases on original DNA
Two new identical DNA molecules are produced
Continued growth and preparation – makes more proteins for the new cell that will be formed; mitochondria and chloroplasts duplicate

4. Visual overview of mitosis

5. Mitosis – early prophase
2. Mitosis – shortest stage where the contents of the nucleus divides resulting in two daughter nuclei; sister chromatids are joined by the centromere (fig 5.7)
Early prophase
Replicated chromosomes coil up into X-shaped chromosomes and become visible 
nucleolus disappears and nuclear membrane begins to break down
Spindle fibres (tube like proteins) begin to form and stretch across the cell from organelles

6. Late prophase and metaphase
Spindle fibres complete forming
Chromosomes attach to spindle fibres at the centromere
Nuclear membrane disappears
Metaphase
Spindle fibres pull the x-shaped chromosomes into a single line across the middle of the cell

7. Anaphase and telophase
Spindle fibres contract and shorten which pulls the centromere apart
Sister chromatids move to opposite poles of the cell
Once separated, each sister chromatid is considered to be a chromosome 
Telophase
One complete set of chromosomes at each pole of the cell 
Spindle fibres disappear and nuclear membrane forms around each set of chromosome
Nucleolus appears within each nucleus 
Cell is ready to divide

8. Cytokinesis and checkpoints
3. Cytokinesis – separates the two nuclei into two daughter cells
Animal cells – the cell membrane pinches together to divide
Plant cells – cell plate forms along the centre of the cell
Checkpoints
Cells will not divide if...
There are not enough nutrients to support cell growth 
DNA within the nucleus has not been replicated 
DNA is damaged

9. Cancer Uncontrolled cell division (checkpoints don’t work)
Healthy cells stop dividing when they receive a message from neighbouring cells but cancer cells don’t
Cancer cells don’t function the same as other cells but they can release chemicals to attract nearby blood vessels to branch into the tumour to feed it
Blood vessels can carry cancer cells to new places in the body