2.6 Cell Cycle

Question 1

What is the overall cell cycle of a eukaryotic cell?

Answer 1

1. Interphase (G0 , G1)
2. S phase
3. G2 phase
4. Mitosis (PMAT)
5. Cytokinesis

Question 2

What is the purpose of checkpoints within the cell cycle?

Answer 2

To prevent uncontrolled division (cancer) and to detect and repair damage in DNA

Question 3

What is the Hayflick constant?

Answer 3

Cells generally only undergo up to 50 divisions before it stops dividing

Question 4

What happens at the M phase?

Answer 4

Cell growth stops and the cell undergoes the stages of Mitosis (PMAT) followed by cytokinesis

Question 5

What happens at the M phase checkpoint?

Answer 5

Chemical triggers condensation of chromatin
Ensures the cell is ready for Mitosis

Question 6

What happens during the G0 phase?

Answer 6

Cell may undergo apoptosis, differentiation or senescence.
Neurons and other cells can stay in this phase for a long time or indefinitely

Question 7

What happens during the G1 phase?

Answer 7

cells grow in size
transcription of gene to make RNA
organelles duplicate
biosynthesis

Question 8

What happens at the G1 checkpoint?

Answer 8

to check the cell is ready to enter the S phase

Question 9

What happens at the S phase?

Answer 9

DNA replicates
(creates a pair of identical sister chromatids)
rapid, susceptible to mutations

Question 10

what happens at the G2 phase and checkpoint?

Answer 10

cells grow
special chemicals are used to check the cell is ready for mitosis
^ these chemicals can be used to make chromosomes condense and form spindle fibers

Question 11

hopefully you haven’t lost ur sheets on mitosis and meiosis, using them is better than this

Answer 11

but anyways where does genetic mutation occur in mitosis?

Question 12

What is it called when 2 chromosomes have the same genes in the same place?

Answer 12

homologous chromosomes

Question 13

Why do animals need specialized cells?

Answer 13

Animals have a small surface area to volume ratio and cannot directly diffuse oxygen into them so need means to do so

Question 14

What specialised animal cells are there?

Answer 14

erythrocytes
neutrophils
spermatozoa
epithelial cells

Question 15

What is an example of an erythrocyte?

Answer 15

a red blood cell

Question 16

What is an example of a neutrophil?

Answer 16

a white blood cell

Question 17

What makes erythrocytes good cells?

Answer 17

7.5 um in diameter so have a large SA:V which is great for diffusion, the biconcave shape also increases the SA:V
They are flexible and a well developed cytoskeleton means they can change shapes as they travel through the blood
Have less organelles so there is more space for haemoglobin

Question 18

What makes neutrophils good cells?

Answer 18

50% of all white blood cells
twice the size of erythrocytes
each contains a multilobed nucleus
attracted and travel to infection sites via chemotaxis
their function is to ingest bacteria by phagocytosis

Question 19

How are spermatozoa specialised?

Answer 19

lots of mitochondria to make ATP for the undulipodium (tail)
small and thin = move easily
enzymes in the acrosome to digest the egg barrier
haploid male gamete in head

Question 20

How are squamous epithelial cells specialised?

Answer 20

they are flat to create a short diffusion distance

Question 21

How are squamous epithelial cells specialised?

Answer 21

they are flat to create a short diffusion distance