The cell cycle

Question 1

What are the 3 stages of the cell cycle?

Answer 1

1. interphase
2. mitosis
3. cytokinesis

Question 2

What are the 3 stages of the interphase and what happens in them?

Answer 2

1. Growth 1(G1), organelles replicate, cell size increases, protein synthesis happens, can respire here to provide energy
2. Synthesis(S), DNA is replicated
3. Growth 2(G2), cell growth, organelle division

Question 3

What are the 3 checkpoints in the cycle and what are their functions?

Answer 3

1. G1 checkpoint, checks cell size+for damaged DNA
2. G2 checkpoint, checks for DNA errors that may have occurred during synthesis, also checks size
3. Spindle fibre checkpoint(in metaphase of mitosis), checks that all chromosomes are attached to the spindle fibres correctly

Question 4

What is G0?

Answer 4

Aka cell arrest, here there is no cell division. Happens when cell leaves the cycle, it may leave because…

1. DNA damage(dont want to make more damaged DNA)
2. If the cell is specialised(dont need to divide)
3. Senescence(old age) stop dividing.

Question 5

What are the 4 stages of mitosis?

Answer 5

Prophase
Metaphase
Anaphase
Telophase

Question 6

What happens in the prophase?

Answer 6

-The chromatin condenses into visible chromosomes

-The nuclear membrane breaks down

-Centrosomes move to opposite poles(ONLY IN ANIMAL CELLS)

Question 7

What happens in the metaphase?

Answer 7

-Chromosomes align at the centre of the plate(metaphase plate)

-Spindle fibres attach to kinetochores(protein structures on centromeres of each chromosome)

Question 8

What happens in the anaphase?

Answer 8

-Sister chromatids separate and are pulled to opposite poles of the cell

-The cell elongates

Question 9

What happens in the telophase?

Answer 9

-The chromosomes reach the poles and begin to decondense

-A new nuclear membrane forms around each set of chromosomes

Question 10

What is cytokinesis?

Answer 10

Happens after the telophase of mitosis, is the division of the cytoplasm. Resulting in two daughter cells.