MITOSIS

Question 1

WHAT ARE THE STAGES OF MITOSIS

Answer 1

PROPHASE
PROMETAPHASE
METAPHASE
ANAPHASE
TELOPHASE
(CYTOKINESIS)

Question 2

WHAT ARE THE ADVANTAGES OF YEAST AS A MODEL FOR THE CELL CYCLE

Answer 2

1. RAPID DIVISION RATE
2. CELL CYCLE CONTROL GENES ARE HIGHLY CONSERVED
3. CAN BE GROWN AS HAPLOIDS OR DIPLOIDS
4. THE CELL CYCLE IS A LOT MORE FLEXIBLE

Question 3

WHAT ARE THE ADVANTAGES OF XENOPUS AS A MODEL

Answer 3

1. EASY TO COLLECT
2. LARGE EGGS
3. RAPID DIVISION RATE
4. SIZE EASIER FOR PROTEIN PURIFICATION
5. CAN BE MANIPULATED EASILY
6. CAN UNDERGO CELL FREE CELL CYCLE

Question 4

WHICH CYCLINS DRIVE ENTRY INTO MITOSIS PHASE

Answer 4

B CYCLINS (CDK1)

Question 5

WHAT HAPPENS IN MITOSIS

Answer 5

1. ASSEMBLY OF MITOTIC SPINDLE
2. SISTER CHROMATIDS ARE ATTACHED TO OPPOSITE POLES
3. CHROMOSOME CONDENSATION
4. BREAKDOWN OF NUCLEAR ENVELOPE
5. REARRANGEMENT OF ACTIN CYTOSKELETON

Question 6

HOW DO M CYCLINS DRIVE ENTRY INTO MITOSIS

Answer 6

M CYCLINS INCREASE THROUGH G2 AND M TO CREATE A POOL OF INACTIVE M-CDK COMPLEX. IN LATE G2, CDC25 PHOPHATE IS TRIGGERED TO ACTIVATE THE M-CDK COMPLEX AND SO MITOSIS.

WEE1 - CDK INHIBITORY KINASE
CAK - ACTIVATING KINASE
BALANCE OF THESE HELPS ENTRY

Question 7

WHAT IS THE ANAPHASE PROMOTING COMPLEX

Answer 7

A PROTEIN THAT IS A UBIQUITIN LIGASE THAT HELPS THE TRANSITION FROM METAPHASE TO ANAPHASE

Question 8

WHAT ARE THE TARGETS OF THE APC

Answer 8

1. SECURIN: IA PROTEIN THAT PROTECTS THE LINKAGES BETWEEN SISTER CHROMATIDS
2. S+M CYCLINS: CYCLINS FROM THE PHASES PREVIOUS

THESE MUST BE DEGRADED IN ORDER TO MOVE TO ANAPHASE

Question 9

HOW CAN YOU GET LOSS OF HETEROZYGOSITY

OR LOSS OF AN ALLELE - HEMIZYGOSITY

Answer 9

1. RECOMBINATION
2. GENE CONVERSION
3. NON DYSJUNCTION

Question 10

WHAT IS LOH BY NON DYSJUNCTION

Answer 10

FOR SUCCESSFUL MITOSIS TO OCCUR, SISTER CHROMATIDS MUST BE PULLED TO OPPOSITE POLES. IF THIS GOES WRONG, YOU MAY HAVE CHROMOSOMES ENDING UP/OR NOT ENDING UP IN THE CORRECT DAUGHTER CELL.

Question 11

WHAT IS LOH BY MITOTIC RECOMBINATION

Answer 11

DURING G2 AND M PHASE WHEN EVERYTHING IS CONDENSING, THERE MAY BE SWAPPING OF CHROMATID ARMS.

Question 12

WHAT IS LOH BY GENE CONVERSION

Answer 12

DNA POLYMERASE BEGINS REPLICATION OF ONE STRAND BY IT MAY ACCIDENTALLY JUMP STRANDS THEREBY, IN THAT PERIOD, COPING ANOTHER STRAND.