Cellcyclle

Question 1

Why is cell division important

Answer 1

– development from a fertilized egg – growth
– repair

Question 2

Cell cycle

Answer 2

is a series of events that take place in a eukaryotic cell leading to its reproduction.

Question 3

Result of mitosis

Answer 3

results in two daughter cells with identical genetic information, DNA

Question 4

Results of meiosis

Answer 4

Meiosisyieldsnonidentical daughter cells that have half as many chromosomes as the parent cell

Question 5

Events of mitosis

Answer 5

• (prophase)condensation of chromosomes, centromere assemble
  -(metaphase)spindle fibre formation and the breakdown of the nuclear membrane
  -(metaphase)alignment of chromosomes on spindle equator ,Nuclear membrane disappear
  -(anaphase)separation of chromosomes/chromatids
  -(telophase)chromosomes de condensed new nuclear membrane form;formation of two new cells

Question 6

The Mitotic Spindle

Answer 6

• The mitotic spindle is a structure made of microtubules that controls chromosome movement during mitosis
• In animal cells,assembly of spindle micro tubules begins in the centrosome, the microtubule- organizing center
• The centrosome replicates during interphase, forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase

Question 7

Cytokinesis

Answer 7

Process of cytoplasm seperation

Question 8

Checkpoints in the cell cycle

Answer 8

• The sequential events of the cell cycle are directed by a distinct cell cycle control system, which is similar to a clock
• The cell cycle control system is regulated by both internal and external signals
• Theclockhasspecificcheckpointswherethe cell cycle stops until a go-ahead signal is received

Question 9

Checkpoints in the cell cycle

Answer 9

-entrance into m blocked if dna replication is not completed
-anaphase blocked if chromatids are not properly assembled on mitotic spindle
-dna damage checkpoint: dna replication halted if genome is damaged
-dna damage checkpoint ;entrance into s is blocked if genome is damaged

Question 10

Cycling

Answer 10

are proteins formed and degraded during each cell cycle.
The cyclins bind to the CDK molecules, therefore regulating the CDK activity and selecting the proteins to be phosphorylated.

Question 11

Who discovered the start gene and check point

Answer 11

L hart well

Question 12

Who discovered CDk

Answer 12

P.nurse

Question 13

Who discovered cyclins

Answer 13

T . Hunt

Question 14

what phases do cyclins control

Answer 14

➢ G1-phase cyclin- cyclin D and E ➢ S-phase cyclins- cyclin E and A ➢ M-phase cyclin- cyclin B

Question 15

What phases do cdks control

Answer 15

➢ G1-phase CDK- CDK4/6
➢ S-phase CDK- CDK2
➢ M-phase CDK- CDK1 (CDC2)

Question 16

What stage do Anaphase-promoting complex (APC, cyclosome) affect

Answer 16

➢ APC triggers the destruction of the cohesins
➢ degrade cyclin B

Question 17

cyclin-dependent kinases (CDKs)

Answer 17

remain fairly stable in the cell , but each must bind the appropriate cyclin in order to be activated.

Question 18

Cell cycle inhibitor

Answer 18

Cyclin Kinase Inhibitors (CKI), block the actions of CDKs

Question 19

Cell cycle and cancer

Answer 19

• Dysregulation of the cell cycle is common during tumorigenesis (cancer display uncontrolled growth)
• Increased levels of CDK molecules and cyclins are sometimes found in human tumours, such breast cancer and brain tumours
• Inhibition of certain CDKs has been shown to inhibit tumour cell growth, induce apoptosis and cause tumour regressions in animal models
• CDKs are potential targets for new anticancer therapy