Why do cells divide?
Cells divide to help replace worn out or dying cells
What are the three stages in the cell cycle?
Interphase
Mitosis
Cytokineses
What is interphase?
Interphase is where the cell grows in size makes proteins and oragenalles and duplicates its DNA.
There are three phases in Interphase:
G0
G1
S
G2
What happens in G0?
The cell is doing its normal functions but won’t divide. Some cells rest in G0 while some stay their permanently
What happens in G1?
The cell is growing bigger and making proteins and organelles
What happens in phase S?
The cell copies all of its DNA
What happens in G2?
The cell grows a bit more and makes specific proteins for mitosis
What are checkpoint proteins
Proteins that monitor cell activity and determine whether (positive) or not (negative) the cell is ready to move into the next stage/phase or division
Where and when do checkpoint proteins occur?
At the end of G1 and G2 as well as during metaphase
What is Mitosis?
Mitosis is the shortest stage. Where one parent cell divides into two identical daughter cells. Mitosis has 4 important stages; PMAT
What does PMAT stand for?
Prophase
Metaphase
Anaphase
Telophase
What happens during prophase?
Chromosomes become visible and the nuclear envelope begins to break down. Spindle fibers begin forming from the centrosomes
What happens during prometaphase?
Spindle fibres connect to the flery moving chromosomes at the centromere
What happens during metaphase
The chromosomes all line up at the centre of the cell
What happens during anaphase
The spindle fibres pull the sister chromosomes apart to opposite sides of the cell
During telophase what happens?
New nuclear membranes develop around the chromosomes on each side of the cell. The cell pinches and develops a cleavage furrow
What happens during cytokinesis
Cytoplasm separates and two new daughter cells are formed
