Cell division

Uncoiled genetic material containing DNA and proteins.

 Half of a chromosome.  Chromosomes are said to be made up of two linked sister chromatids.

Coiled up version of genetic material containing DNA and proteins.  Rod or X shaped.

The centre point of a chromosome where the sister chromatids join.

The protein portion of the chromatin/chromosome.

Identical pairs of chromosomes in the same cell.

A cell that has homologous chromosome pairs in it.  Notated as 2N.

A sex cell that only has one of each chromosome.  No homologous pairs.  Notated as 1N.

• Examples of this would be sperm or egg cells.

G1 Period

During the G1 period, a cell shows a lot of growth.  It doubles in size and doubles the number of many organelles inside of it.  (Which ones would double?)

S Period

During the S period, the cell is making more DNA.  Replicates existing DNA to result in sister chromatids.

G2 period

G2 is another period of major growth.  The cell is making sure to build everything it needs (ex. enzymes) to successfully pull off cell division in the mitosis phase.

1. The chromatin starts to coil up to form chromosomes.

2. The nucleolus and nuclear membrane are broken down and disappear in the cell.  

3. Centrioles are formed and migrate to opposite ends of the cell.

4. Spindle fibers (made from microtubules) are formed and extend out from the centrioles.  They can go from centriole to centriole or centriole to centromere.

all of the chromosomes are lined up in the centre of the cell

Anaphase is when the sister chromatids finally break apart.  Once separated, each chromatid moves in opposite directions towards the centrioles at the poles of the cell.

1. Chromatids are grouped together at either end of the cell now.

2. The centrioles and spindle fibers are broken down and disappear.

3. The chromatids unwind resulting in a large mess of chromatin now.

4. A nuclear membrane forms around the chromatin.

5. A nucleolus appears on the newly formed nucleus.