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MCBM Exam 5 Kat > Cell Cycle Regulation And Disruption > Flashcards

Cell Cycle Regulation And Disruption Flashcards

0
Q

What is cell division control provided by?

A

CDKs - cyclin dependent kinases

Cyclins - kinase regulatory proteins

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1
Q

What does uncontrolled cell division result in?

A

Cancer

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2
Q

What happens if the cell cycle is not initiated by external sequences?

A

They enter into a prolonged G1(G0) due to lack of G1 cyclins which are destroyed during mitosis

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3
Q

What cyclins and CDK make up the complex G1-Cdk?

A

Cyclin D1, D2 and D3

Cdk4, Cdk6

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4
Q

What cyclins and CDK make up the complex G1S-Cdk?

A

Cyclin E

Cdk2

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5
Q

What cyclins and CDK make up the complex S-Cdk?

A 
Cyclin A (SPF)
Cdk2
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6
Q

What cyclins and CDK make up the complex M-Cdk?

A 
Cyclin B (MPF)
Cdk1
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7
Q

How are Cdk/cyclin complexes regulated?

A

Cyclic proteolysis
Transcriptional regulation
Inhibitor proteins (CKIs)
Covalent modification (phosphorylation/dephosphorylation)

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8
Q

What challenges are present in each cell division?

A

Must not replicated damaged DNA
Must replicate one, and only one, complete copy of the genome
Must properly segregate a complete copy to each daughter cell

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9
Q

What happens at the G1/S checkpoint?

A

DNA damage assessment

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10
Q

What happens at the mid S checkpoint?

A

DNA replication checkpoint I

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11
Q

What happens at the G2/M checkpoint?

A

DNA replication checkpoint II

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12
Q

What happens at the M checkpoint?

A

Spindle assembly checkpoint

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13
Q

What happens at the post M checkpoint?

A

Polyploidy checkpoint

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14
Q

What happens if there is a problem with the polyploidy checkpoint?

A

Leads to tetraploidization

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15
Q

What happens if there are problems at the DNA replication checkpoint?

A

Leads to telomere dysfunction, rearrangements and amplifications

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16
Q

What do tumor suppressors do when they find irreparable damage to DNA?

A

Send into programmed cell death

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17
Q

What are the best described tumor suppressors?

A

p53 and pRb; both of which are transcription regulators

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18
Q

What is p53 considered and why?

A

It is considered the guardian of the genome because it halts the cell cycle in response to DNA damage thus allowing time for repair

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19
Q

What are some genes that p53 regulates?

A

p21: mitotic arrest
GADD45: DNA repair protein

20
Q

What happens when p53 becomes mutated?

A

Converts from a tumor suppressor to an oncogene.

Associated with ~50% of all tumors when mutated

21
Q

When is p53 activated/phosphorylated?

A

In response to DNA damage

22
Q

When is pRb inactivated/phosphorylated?

A

In response to cdk2 resulting in released E2F that can bind DNA and regulate expression of cell division genes

23
Q

What happens in M phase following G2?

A 
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
24
Q

What happens in prophase?

A

Chromosomes condense; nucleoli disappear, mitotic spindle forms

25
Q

What happens in prometaphase?

A

Nuclear membrane breaks down; chromosomes attach to spindle

26
Q

What happens in metaphase?

A

Chromosomes maximally contracted and arranged at equatorial plane

27
Q

What happens in anaphase?

A

Centromeres split and sister chromatids separate to opposite poles

28
Q

What happens in telophase?

A

Chromosomes decondense, nuclear membrane reforms, cytokinesis

29
Q

What is required in metaphase to anaphase transition?

A

M-Cdk inactivation required.

30
Q

What is required from prophase to metaphase?

A

Active m-Cdk

31
Q

What are the targets of M-Cdk?

A

Condensins

Laminin

32
Q

What are Condensins?

A

Proteins involved in chromosome condensation

33
Q

What does phosphorylation of laminin cause?

A

Causes it to depolymerize, resulting in nuclear envelope breakdown

34
Q

What does APC affect?

A

Securin
Separase
Cohesins

35
Q

What is securin and what is one of its functions?

A

Separase inhibitor

It initiates anaphase (APC target)

36
Q

What is separase?

A

A protease that targets cohesion to allow sister chromatid separation

37
Q

What is involved in programmed cell death?

A

Removal of factors
Extracellular signals
Cell damage

38
Q

What are oncogenes?

A

Mutated forms of normal proteins (proto-oncogenes) involved in control of cell growth

39
Q

How can viruses become tumor causing?

A

1) virus inserts into host genome
2) when excised May take a cope of genome with it
3) mutates the genome
4) reinfect and inserts mutated gene into new host

40
Q

What are some known oncogenes?

A

Mutant G proteins and tyr-kinases?

41
Q

What does erbB encode?

A

EGF receptor lacking EGF binding domain

42
Q

What does sis encode?

A

Mutant PDGF receptor

43
Q

What does ras encode?

A

A G protein with no intrinsic GTPase activity

44
Q

What does myc encode?

A

A transcription factor that regulates proliferative proteins

45
Q

What is different about the ErbB protein?

A

Tyrosine kinase is constantly active

46
Q

What is HPV highly associated with?

A

Cervical cancer

47
Q

What do the early HPV proteins (E6 & E7) do?

A

They bind and inactivate p53 and pRb the tumor suppressing proteins

48
Q

What else does HPV E6 do?

A

Targets Bcl2 which helps maintain a cell that should undergo apoptosis

MCBM Exam 5 Kat (15 decks)

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