Cell Cycle

Question 1

what allows cancers to pick positive hallmarks

Answer 1

genetic variability created by uncontrolled error prone cell division

Question 2

what is chromosome instability aka CIN

Answer 2

when cancer cells display a high amount of chromosome numerical or structural alterations

Question 3

what does chromosomal instability allow cancers to do

Answer 3

constantly shuffle their genome and find genetic variations that suit their environment
this is the driving force fuelling evolution

Question 4

is chromosomal instability a good a bad prognostic factor

Answer 4

bad

more genetic diversity means more chance of becoming resistant to chemo

Question 5

what happens in S phase

Answer 5

chromosomes duplicate

Question 6

what happens in M phase

Answer 6

duplicated chromosomes (sister chromatids) are segregated to opposites poles of the cells and packaged into genetically identically daughter cells

Question 7

what happens to all the other cell components during cell division

Answer 7

are duplicated

Question 8

what phases are contained within M phase

Answer 8

mitosis and cytokine

Question 9

what happens in mitosis

Answer 9

chromosomes segregates and packaged into individual nuclei

Question 10

what happens in cytokinesis

Answer 10

process by which nuclei are distributed by cell division into a pair of genetically identical daughter cells

Question 11

what is the mitotic spindle

Answer 11

bipolar array of microtubule polymers that forms as the cells enter mitosis and then attaches to the chromatid pairs

Question 12

what is the microtubule - chromatid attachment site called

Answer 12

the kinetochore (large protein complex)

Question 13

how are the chromatids separated

Answer 13

Chromosomes align along the middle of the mitotic spindle, protein glue holding sister chromatids together dissolves, allowing them to be pulled to both poles in anaphase and then packaged into individual nuclei, then distributed by cytokinesis into the daughter cells

Question 14

what happens in prophase

Answer 14

chromosomes condense in nucleus
changes occur in microtubule cytoskeleton- two organising centres move apart along the surface of the nucleus to begin to form spindle
nuclear envolope dissolves allowing microtubules access to chromatids

Question 15

what are the stages of mitosis

Answer 15

prophase
metaphase
anaphase
telophase

Question 16

what happens in metaphase

Answer 16

chromatids attach to the mitotic spindle in a bi oriented fashion (one goes to one pole, the other to the other)
(chromosome cohesion mechanisms removed)

Question 17

what happens in anaphase

Answer 17

chromatids pulled apart

Question 18

what happens in telophase

Answer 18

packaging of chromosome sets into individual daughter cells

Question 19

what does CDC16 do

Answer 19

encode component of protein complex needed for progression through metaphase anaphase transition

Question 20

what does CDC15 do

Answer 20

encodes a component of a regulatory network that drives the cell out of anaphase and into the following g1

Question 21

what is the domino effect in cell cycle

Answer 21

dependency relationships among the events in the cell cycle, events regulate each other, one must happen in order for the others to happen

Question 22

what is the clock effect in cell cycle

Answer 22

intrinsic biological timer that turns on cell events at specific times and in a specific order

Question 23

what controls the cell cycle

Answer 23

a series of biochemical switches that turn on specific cell cycle events in a specific order and in a specific time. These events can feed back to this timer to arrest or adjust these events if necessary (if conditions not appropriate)

Question 24

what are the three major transitions/ checkpoints of the cell cycle

Answer 24

G1-S (start
G2-M
metaphase - anaphase transition

Question 25

what is the key control mechanism of the cell cycle

Answer 25

cyclin dependent kinases | these are protein kinases

Question 26

how do you activate CDKs

Answer 26

bind with cyclin (their regulatory partners) which forms active CDK-cyclin complex

Question 27

what does the cdk-cyclin complex do

Answer 27

phosphorylates large number of substrates in the cell resulting in the onset of specific cell cycle events their activation triggers specific events at specific times in cell cycle

Question 28

what else regulates CDKs

Answer 28

phosphorylation of the CDK subunit and inhibitory proteins

Question 29

what happens to cyclin levels during mitosis- why

Answer 29

drop as cyclin destruction is needed for the exit from mitosis (cells with v stable cyclin wont enter mirosis) happens as anaphase promoting complex (cyclosome) triggers the met-ana transisiton, its activity rises in mid mitosis causing the destruction of cyclins

Question 30

what type of molecule is APC

Answer 30

ubiquitin protein ligase / E3

Question 31

how does APC destruct cyclins

Answer 31

catalyzes the attachment of a small protein called ubiquitin onto its target by attaching large numbers it sends them to a protease in the cell called the proteasome where they are destroyed

Question 32

what else does APC target

Answer 32

the protein securin

Question 33

what does securin do

Answer 33

tight binding inhibitor of a protease called separase

Question 34

what does destruction of securin by APC do

Answer 34

releases separase which goes to the sister chromatids and cleaves a single subunit protein complex called cohesion that holds the chromatids together this causes the chromatids to separate and be segregated by microtubules

Question 35

what does APC directly trigger

Answer 35

initiation of anaphase

Question 36

how quickly are CDKs activated

Answer 36

switch like- v quick

Question 37

what are CDC genes

Answer 37

universal regulators of the cell cycle

Question 38

what is CDC 28 (aka CDK1)

Answer 38

master regulatory kinase that controls the progression of cells through the start of the cell cycle