Cell bio 2017 old exam 4

what happens to the likelihood of apoptosis occurring if Increased CED-9

Apoptosis more likely

what happens to the likelihood of apoptosis occurring if Procaspase 9 can self proteolytically cleave

Apoptosis more likely

Match the mutated versions of the genes below with the gene categories. a. Proto-oncogene b. Tumor suppressor gene c. Oncogene d. None of the above 1. P53 2. BRCA1 3. Myc

1. B 2. B 3. C

You have isolated and sequences a region of DNA that appears to have caused tumor formation. Match the types of mutation with the description to understand how that DNA causes the cancer and the characteristic of each type of mutation you might find? a. Point mutations b. Local DNA rearrangement c. Chromosomal translocation d. Insertional mutagenesis e. Gene amplification 1. Rous sarcoma virus 2. Bcr-Abl 3. TRK oncogenes

1. E 2. B 3. C

what happens to the likelihood of apoptosis occurring if Inactivating mutation of Bim

Apoptosis less likely

Which of the following types of mutation in a proto-oncogene cannot give rise to an oncogene? Addition or deletion of a base producing an activated receptor even in the absence of a ligand ? (Would it have an active or inactive protein product) A point mutation changing just one amino acid in the protein product, altering the codon A translocation that puts the gene under the control of a stronger promoter, producing over-expression A point mutation that produces a stop codon, prematurely terminating the message and producing a truncated protein Any type of mutation can produce an oncogene

A point mutation that produces a stop codon, prematurely terminating the message and producing a truncated protein

Which of the following types of protein could be coded by a tumor-suppressor gene? A protein that forms part of a growth factor signaling pathway (proto-oncogenes) A protein that codes for a DNA repair enzyme (genome maintenance genes) A protein that helps prevent apoptosis (proto-oncogenes) A protein that controls progression through the cell cycle (tumor-suppressor genes) A tyrosine kinase (proto-oncogenes, src)

A protein that controls progression through the cell cycle (tumor-suppressor genes)

Which of the following best defines an oncogene? An oncogene codes for a cell cycle control protein An oncogene codes for a mutation form of a protein that forms part of a signal transduction pathway An oncogene codes for a protein that prevents the cell from undergoing apoptosis An oncogene is dominantly expressed mutated gene that gives a cell a growth or survival advantage Oncogenes are the precursors of proto-oncogenes

An oncogene is dominantly expressed mutated gene that gives a cell a growth or survival advantage

select the checkpoint or phase change associated with the following molecule: Cdc14 phosphatase

Anaphase to telophase transition

what happens to the likelihood of apoptosis occurring if Cytochrome C cannot leave the mitochondria

Apoptosis less likely

True or False: Protein kinase B phosphorylates Bad and other anti-apoptotic proteins making them inactive?

True

What roles in regulating the intrinsic pathway of apoptosis are played by the Bcl-2 protein family members? Both Bax and Bcl-2 inhibit apoptosis Both Bax and Bcl-2 stimulate apoptosis Only Bax and its homolog Bak are involved in stimulating apoptosis, Bcl-2 is not involved Bax inhibits apoptosis while Bcl-2 stimulates apoptosis Bax stimulates apoptosis while Bcl-2 inhibits apoptosis

Bax stimulates apoptosis while Bcl-2 inhibits apoptosis

Cyclin dependent kinases that control progression through cell cycle checkpoints are fully activated by which of the following mechanisms? Binding to cyclins Phosphorylation by Cdk activating protein kinase Binding to cyclin, plus phosphorylation by a Cdk activating protein kinase Phosphorylation by a tyrosine kinase Dephosphorylating of CDKs

Binding to cyclin, plus phosphorylation by a Cdk activating protein kinase

Each of the following would inhibit cell progression through the cell cycle except DNA damage during the S-phase of replication CAK kinase phosphorylation of the M-cyclin/Cdk complex APC/C-Cdh1 activity during early M phase Unphosphorylated retinoblastoma activity during G1 A loss of function mutation in the SCF gene

CAK kinase phosphorylation of the M-cyclin/Cdk complex

Cells lacking the ability to produce a functional caspase 9 protein are cultured in the presence of a growth factor. Expression of a constitutively active version of which one of the following proteins could induce apoptosis in these cells. Apaf-1 Bcl-2 EGF Caspase 3 Cytochrome C

Caspase 3

Which of the following is false about caspases? Caspases are activated by proteolytic cleavage Caspases cleave proteins after aspartates Are cysteine dependent Are key elements of active apoptosomes The APAF-1 caspase forms apoptosomes

Caspases cleave proteins after aspartates

The mitotic exit network requires which of the following activators? Cdc14 Cdc20 Cdc25 Wee1 Cdh1

Cdc14

Individuals can inherit a defective APC gene on chromosome 5 from one parent that makes them susceptible to developing familial adenomatous polyposis. In which cells is this deletion present in affected individuals? Somatic cells Germ cell precursors Colon polyp cells Colon epithelial cells All cells

Colon epithelial cells

The passage of a cell through the stages of the cell cycle is controlled by protein kinases that phosphorylate many different proteins at appropriate times. What are these proteins kinases called? Cdk activating kinases Cyclins Tyrosine kinases Phosphorylation kinases Cyclin-dependent kinases

Cyclin-dependent kinases

Virus infected cells are killed by the extrinsic apoptosis pathway involving which of the following? Damaging DNA by necrosis effects Killing nerve cells that fail bind a trophic survival factor Irradiation of cells Cytotoxic T lymphocytes The intrinsic pathway kills virus infected cells preferentially

Cytotoxic T lymphocytes

True or false: CED9 and BCL-2 are homologues (both promote cell survival; prevent CED4 and Apaf1 activation, respectively)

True

M-cyclin levels at the end of mitosis are regulated by which one of the following: Phosphorylation of M CDKs Phosphorylation of the M cyclin mRNAs Degradation of M cyclin by APC/C-Cdh1 Degradation of M cyclin by phosphorylated APC/C-Cdh1 Degradation of M cyclin by APC/C-Cdc20

Degradation of M cyclin by APC/C-Cdh1

Which of the following proteins is a death receptor adaptor that helps to trigger the extrinsic pathway of apoptosis? Caspase-8 Fas95 Fas ligand Caspase-9 FADD

FADD

True or False: APC/C - Cdc20 leads to degradation of cohesins which holds the sister chromatids together, leading to the metaphase to anaphase transition

False

Mitogens are added to the medium of cultured human cells that are synchronized in mitosis. The mitogen is washed away after these cells have passed START in the cell cycle. These cells will progress through the cell cycle then arrest in which phase? S-phase G2 G0/G1 Mitosis Cell cycling just keeps repeating

G0/G1

Sic1 is targeted by SCF during which phase, leading to the cell moving through the next checkpoint? G1 to S S to G2 G2 to M Metaphase to anaphase transition Exit from mitosis

G1 to S

select the checkpoint or phase change associated with the following molecule: Cdc25 phosphatase

G2/M transition

What structure attaches the centrosome to the mitotic spindle? Kinetochore Centriole Securin/separase complex APC/C complex M-cyclin/CDK complex

Kinetochore

In what way does the ras contribute to cancers? Ras codes for an anti-apoptotic protein, which is produce in abnormally large amounts Ras codes for a monomeric GTPase switch protein, which in its mutated form cannot be switched off Ras codes for a transcription factor, which is produce in abnormally large amounts Ras codes for a truncated form of a growth factor receptor, which is continually active Ras is trimeric G-protein, which in its mutated form cannot be switched off

Ras codes for a monomeric GTPase switch protein, which in its mutated form cannot be switched off

Which of the following statements about the Rb tumor-suppression protein in its normal state is not correct? Rb is activated and binds E2f when phosphorylated by G1-cyclin/Cdk Rb binds the transcription factor E2f and thus prevents the cell from entering S phase until a mitogenic signal is received Rb is a transcription factor leading to downstream transcription of the E2f gene When a mitogenic signal is received, Rb binds the transcription factor E2f and thus stimulates the cell to enter S phase Rb is not a tumor suppressor gene until its mutated

Rb is not a tumor suppressor gene until its mutated

Which of the following is believed to be a key cause of immortalization of cancer cells in many tumors? Complete loss of telomeres Inactivation of the telomerase enzyme Reactivation of the telomerase enzyme Shortening of telomeres Immortalization does not involved telomeres

Reactivation of the telomerase enzyme

Most hereditary forms of breast and ovarian cancer arise in women who inherit a mutant copy of either the BRCA1 or BRCA2 gene, each of which encodes proteins involved directly in: Inhibiting apoptosis Passing through the G1 restriction point A spindle assembly checkpoint Activating Rho proteins to increase cell motility Repairing DNA double-strand breaks

Repairing DNA double-strand breaks

Each of the following occurs during apoptosis of a cell except Flipping phosphatidylserine to the outer leaflet of the plasma membrane Plasma membrane bled formation Rupture of the cell, releasing cytoplasmic contents for phagocytes Formation of apoptotic bodies DNase regulate fragmentation of DNA

Rupture of the cell, releasing cytoplasmic contents for phagocytes

During which stages is APC/C-Cdh1 active Second half of mitosis and G1 (correct, slide 23 on ppt 1) All of mitosis and G1 G1 and S S, G2, and all of mitosis S, G2, and first half of mitosis

Second half of mitosis and G1 (correct, slide 23 on ppt 1)

M-cyclin is present from S-phase but is inactive in the cyclin-Cdk complex by which of the following? Cdc25 phosphatase Sic1 Cdc14 phosphatase Wee1 kinase CAK kinase

Sic1

select the checkpoint or phase change associated with the following molecule: G1/S cyclin

Start/restriction point

Look closely at the figure below and identify the stages of mitosis in the figure. Which of the following is the correct listing of stages of mitosis in the figure from A through D? Metaphase, anaphase, telophase, cytokinesis Telophase, prophase, anaphase, prometaphase Anaphase, telophase, prometaphase, metaphase Telophase, S-phase, anaphase, metaphase M-phase, S-phase, anaphase, metaphase

Telophase, prophase, anaphase, prometaphase

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? Cells would not be able to replicate their DNA The mitotic spindle could not assemble Cells would get larger and larger The cells produced would get smaller and smaller The cells would arrest after M in G0/G1

The cells produced would get smaller and smaller

All of the following statements about destruction of cyclins are true except: Destruction is carried out by proteasomes Destruction is preceded by polyubiquitylation Ubiquitinylation occurs at specific sites on target molecules Ubiquitin targets cyclins Ubiquitin targets cdks

Ubiquitin targets cdks

Which of the following is characteristic of a malignant rather than a benign tumor? Undergoes metastasis Develops a blood supply Cells divide an unlimited number of times Grows without needing a growth signal Cells ignore apoptosis signals

Undergoes metastasis

True or false: both copies of a proto-oncogene must be activated by mutation in order to contribute to cancer development.

false

The cell is not allowed to pass the cell cycle restriction point if DNA damage is detected. Which of the following proteins are involved in detection of DNA damage and inhibition of the cycle at the restriction point? M-cyclin p53 ATV ATM Replication protein A

p53