the cell cycle

Question 1

Describe interphase of part of the cell cycle

Answer 1

G1: growth and prep for S phase
S: chromosomes duplicate for DNA synthesis
G2: growth and prep for M phase

Question 2

Describe mitosis and cytokinesis

Answer 2

M is nuclear division
M consists of P, Prometaphase, M, A, T and CK

CK is the cytoplasmic division
CK: at position of metaphase plate. Contractile ring of actin and myosin II constrict the cell into 2 new cells

Question 3

Describe the mitosis spindle

Answer 3

Starts assembling during prophase from centrosomes
Function is separate duplicated chromosomes
Constructed from microtubules; astral, kinetochore, interpolar
Chromosomes attach to spindle via kinetochore

Question 4

Describe the centrosome cycle

Answer 4

• microtubule-organising centre in animals
• centrosome consists of a pair of centrioles surrounded by pericentriolar material
• duplicated during interphase
• migrate to opposite poles in preparation for M phase

Question 5

Describe cytokinesis in more detail

Answer 5

-contractile ring divides cell in two
-cytoskeleton structure; actin and myosin
-accumulates between the poles of mitosis spindle beneath plasma membrane
-ring contracts and forms indentation or cleavage furrow dividing the cell into 2 new cells
ALL CELL ORGANELLE MUST BE REDISTRIBUTED BETWEEN. TWO CELLS

Question 6

Describe prophase

Answer 6

Chromosomes condense, centrosomes move to opposite poles, and mitosis spindle forms

Question 7

Prometaphase

Answer 7

Breakdown of nuclear envelope

Chromosomes attach to mitosis spindle

Question 8

Metaphase

Answer 8

Centrosome are at opposite poles, chromosomes are most condensed and line up at equator of mitotic spindle

Question 9

Anaphase

Answer 9

Sister chromatids separate synchronously, each new daughter chromosome moving to the opposite spindle pole

Question 10

Telophase

Answer 10

Chromosomes arrives at the spindle poles
Chromosomes decondense
Nuclear envelope reforms

Question 11

Discuss the differences between mitosis and meiosis

Answer 11

MITOSIS: 2 cells, 1 round of cell division, diploid, no recombination, asexual
MEIOSIS: 4 cells, 2 rounds of cell division,haploid, recombination, MI= homologous chromosome line up on spindle and separate to opposite spindle poles
MII: sister chromatids^

Question 12

How is the cell cycle controlled in yeast compared to higher eukaryotes?

Answer 12

-phases must be in correct order + non-overlapping
YEAST: single Cdk binds to different cycling.
S-cyclin:triggers S phase and M-cyclin: triggers M phase
HUMANS: different classes of Cdk and cycling at each stage of cell cycle
G1:Cyclin D (CDK4), G1 to S: Cyclin E(CDK2) , S: Cyclin A (CDK2), S to M: Cyclin B (CDK1)

Question 13

Describe different checkpoints

Answer 13

G1: checks DNA for damage and checks extracellular environment
G2: checks DNA for damage and replicated
M: checks all the chromosomes are aligned on mitotic spindle

Question 14

Cdk and Cyclin levels?

Answer 14

Cdk - stable throughout

Cyclin vary at each stage

Question 15

Cdk and Cyclin interaction

Answer 15

Cdk bound to Cyclin is active and can phosphorylase target proteins

Question 16

Cdk activated triggers…

Answer 16

Next step in cell cycle such as entry into S phase, M phase

Question 17

Cyclin degradation…

Answer 17

Terminates Cdk activity

Question 18

Cdk means…

Answer 18

CYCLIN DEPENDENT KINASES

Question 19

What is neoplasia?

Answer 19

• uncoordinated cell growth
• cells that escape normal cell cycle regulation lead to uncontrolled progression through cell cycle
• genes that are mutated in cancer are regulators of cell cycle such as p53 and pRB which are tumour supporter genes