Smith

Question 1

A protooncogene is one which?

a) generally shows a recessive phenotype when mutated.
b) will cause cells to proliferate when it is mutated.
c) regulates normal cell growth and division.
d) is an antiproliferative gene.
e) is activated during mitosis.

Answer 1

b) will cause cells to proliferate when it is mutated.

Question 2

When a growth factor binds to its receptor molecule, a common sequence of event is?

a) Activation of the receptor—oligomerization of the receptor—creation of docking sites—recruitment and activation of signaling enzymes.
b) Oligomerization of the receptor—activation of the receptor—creation of docking sites—recruitment and activation of signaling enzymes.

Answer 2

Oligomerization of the receptor—activation of the receptor—creation of docking sites—recruitment and activation of signaling enzymes.

Question 3

Which of the following is critical to the formation of a docking site?

An intrinsic protein tyrosine kinase

Retinoblastoma

GAP

Grb2

An intrinsic phosphotyrosine phosphatase

Answer 3

An intrinsic protein tyrosine kinase

Question 4

It has been found in some breast cancer patients that Cyclin D1 expression is increased. How would this affect the retinoblastoma protein?

It would be hyperphosphorylated and thus inactive.

It would be hyperphosphorylated and thus constitutively active.

It would be degraded by caspases.

It would bind to transcription factors of the E2F family.

It would bind to Ras.

Answer 4

It would be hyperphosphorylated and thus inactive.

Question 5

p53 may activate apoptosis, at least in part, by downregulating the expression of ______ and upregulating the expression of _____.

Bcl-2, Bax

Bax, Bcl-2

Caspases, Bax

Caspases, Bcl-2

Answer 5

Bcl-2, Bax

Question 6

While viruses can gain control of the expression of a protooncogene, leading to cellular transformation, 85% of human tumors are simply caused by

Point mutations or deletions in tumor suppressor genes.

Routine intron splicing that leads to activation of a protooncogene.

Ras mutations.

Point mutations or deletions in oncogenes.

p53 mutations.

Answer 6

Point mutations or deletions in oncogenes.

Question 7

HPV E7 can inhibit the association of Retinoblastoma (Rb) with _______, thereby leading to cell immortalization.

Epidermal growth factor (EGF)

Platelet derived growth factor (PDGF)

Transcription factor E2F

p53

Cyclins

Answer 7

Transcription factor E2F

Question 8

As part of a cytokine-dependent pathway to cell growth, ______ can phosphorylate ______, leading to the transcription of GAS elements.

Retinoblastoma, itself

JAKs, STAT

PDGF, itself

Retinoblastoma, E2F

Sos, Ras

Answer 8

JAKs, STAT

Question 9

In the PDGF-mediated pathway of cell growth, _________ acts as a guanine nucleotide exchange factor that will _________ Ras.

Grb2, activate

GAP, activate

GAP, inactivate

Sos, activate

Sos, inactivate

Answer 9

Sos, activate

Question 10

As smoking has declined in the U.S., __________ has taken over as the most commonly encountered risk factor associated with oral cancers.

Alcohol consumption

Use of mouthwash

Poor hygiene

Betel quid use

HPV infection

Answer 10

HPV infection

Question 11

Protooncogene is a normal cellular gene that functions in cell proliferation. These _______ signaling molecules, etc. that keep telling the cell to ________.

Answer 11

encode; cell to divide

Question 12

Oncogenes are

Answer 12

mutated protooncogenes

Question 13

What are antiproliferative genes?

Answer 13

tumor suppressor genes

Question 14

The mutant phenotype of a protooncogene is _____ and occurs with a mutation in _____ allele(s).

Answer 14

dominant; one allele

Question 15

The mutant phenotype of a tumor supressor gene is _____ and occurs with a mutation in _____ allele(s).

Answer 15

recessive; both alleles which leads to uncontrolled cell division!

Question 16

Cell division limitations of:

1) unicellular organisms
2) multicellular organisms

Answer 16

1) primary limitation s availability of nutrients and energy

2) usually stop dividing when they bump up against another cell (regardless of availability of nutrition)

Question 17

In multi-cellular organisms, even _______ is controlled.

Answer 17

apoptosis (cell death0

Question 18

In unicellular organisms, the more divisions, the more______.

Answer 18

mutations = faster evolution

Question 19

Timing of the cell cycle:
S through M:
M:
G0

Answer 19

S through M: 12-24 hr
M: ~1 hour
G0: vast majority of the cell cycle period

Question 20

Environmental signalling molecules at G1 and G2 checkpoints:

Answer 20

hormones, cytokines, and growth factors; also PTK (protein tyrosine kinases) are often involved in checkpoint signaling

Question 21

enzymes that transfer the gamma phosphate from ATP to a tyrosine on a target (substrate) protein. Targets can be intrinsic or extrinsic.

Answer 21

PTK (protein tyrosine kinases)

Question 22

On a general transmembrane PTK, there are 3 domains:

Answer 22

external (receptor for tyrosine kinase), transmembrane, and internal domain (tyrosine kinase domain)

Question 23

What binds to the external domain of an transmembrane receptor?

Answer 23

external signaling factor (dimer)

Question 24

Growth factors are signals for________.

Answer 24

proliferation

some can induce cell growth, but not division!

Question 25

Breast cancer: cyclin D1 expression increased causing…

Answer 25

hyperphosphorylation and inactivation of RB = deregulated malignant cell proliferation

Question 26

Retinoblastomas: mutational inactivation of Rb genes causing…

Answer 26

deregulated malignant cell proliferation

Question 27

Cervical cancer: sequestration of Rb by HPV E7 protein causing….

Answer 27

loss of Rb control of the cell cycle

Question 28

When there is a deletion of the CDK1 gene causing….

Answer 28

loss of inhibition of cyclin-D- CDK4/6 complexes, resulting in loss of Rb control of the cell cycle

Question 29

Bcl-2 is __________, which promotes the survival of the cell.

Answer 29

antiaoptotic

Question 30

Survival factors activate ________ proteins, which lead to the survival of the cell.

Answer 30

Bcl-2

Question 31

P21 is a CDK inhibitor, thus inhibits _______ which doesn’t allow for the _____ checkpoint.

Answer 31

Rb; G1 checkpoint

Question 32

When Rb is phosphorylated, it goes or doesn’t go past the G1 checkpoint?

Answer 32

doens’t go past G1 checkpoint

Question 33

Cyclins interact with ____ which leads to the phosphorylation of Rb

Answer 33

CDK’s

Question 34

p53 is a …

Answer 34

tumor supressor gene

Question 35

CDKIs =

Answer 35

cyclin dependent kinase inhibitors

Question 36

1. Cytokines bind to receptor causing_______ to occur
2. JAKs is ______.
3. JAKs phosphorylates _____.
4. STAT _____.
5. and thus migrates to the nucleus to activate transcription factors!

Answer 36

1. oligomerization
2. JAKs is recruited.
3. phosphorylates STAT
4. STAT dimerizes