Quiz 6,7,8 answers

Question 1

The choice that does not accurately describe Cytokine receptors
1. Can bind more than one kind of cytokine, even as many as 10 different cytokines
2. Can have long disordered regions ranging over 600 residues
3. transmembrane proteins with extracellular, intracellular and transmembrane regions
4. diverse number of extracellular domains
5. some have intracellular Ig domains

Answer 1

5. some have intracellular Ig domains

Question 2

If the common gamma chain acquired a mutation that inhibited PI3KAkt signaling, the cell would be more likely to__
1. undergo cell division
2. remain unaffected
3. survive
4. undergo apoptosis
5. lose transcriptional activity

Answer 2

4. undergo apoptosis

Question 3

cAMP is a second messenger that:
1. leads to phosphorylation of cytoplasmic and nuclear proteins by PKA
2. binds the catalytic domain of PKA
3. creates a membrane docking site for signaling proteins
4. is generated by adenylate cyclase by cyclizing 5’-AMP
5. activates adenylate cyclase

Answer 3

1. leads to phosphorylation of cytoplasmic and nuclear proteins by PKA

Question 4

Cytokines are proteins that
1. have diverse function, including one protein that can be either anti-inflammatory or pro-inflammatory
2. bind an extracellular receptor on only one specific type of cell, most of these cell types being in the immune system
3. have similar molecular weight and mostly helical structure
4. are rarely linked to disease but have been targeted for cancer and autoimmune treatment

Answer 4

1. have diverse function, including one protein that can be either anti-inflammatory or pro-inflammatory

Question 5

All below mechanisms contribute to termination of GPCR-mediated signal transduction EXCEPT:
1. B-arrestin binding to the GPCR
2. Exchange of GDP for GTP on Ga
3. Acceleration of GTPase activity by RGS proteins
4. Phosphorylation of the GPCR by GRK
5. Breakdown of cAMP by PDE

Answer 5

2. Exchange of GDP for GTP on Ga

Question 6

Cell surface receptors with seven transmembrane domains signal by
1. acting as GTPase
2. binding to and co-localizing several proteins
3. acting as a guanine nucleotide exchange factor
4. opening a calcium channel
5. tyrosine phosphorylation

Answer 6

3. acting as a guanine nucleotide exchange factor

Question 7

Which of the following enzymes phosphorylate licensing factors to initiate replication?
1. CDK2
2. Cyclin H
3. Cyclin A
4. Cdc6
5. CDC45

Answer 7

1. CDK2

Question 8

Gleevac (imatinib) treatment produces a prolonged remission (but not a cure) of most cases of CML. In all the responsive cases, the Abl tyrosine protein kinase activity in the cancer cells has been activated by
1. aberrant recombination that caused loss of the inhibitory domain from the catalytic domain
2. gene duplication
3. mutational activation of the activation loop
4. increased transcription
5. mutational activation of an upstream activating protein kinase

Answer 8

1. aberrant recombination that caused loss of the inhibitory domain from the catalytic domain

Question 9

Inositol tri-phosphate, IP3, is produced by which enzyme activity?
1. GTPase
2. tyrosine kinase
3. calmodulin
4. phospholipase C
5. adenylate cyclase

Answer 9

4. phospholipase C

Question 10

In Gq signaling, cytoplasmic calcium levels increase as a result of
1. phosphorylation of G-proteins
2. calcium pumps
3. binding of Gaq to adenylate cyclase
4. active transport driven by the high calcium concentration in the extracellular space
5. passive diffusion of calcium from the ER through gated channels

Answer 10

5. passive diffusion of calcium from the ER through gated channels

Question 11

What are the signaling receptors?

Answer 11

intracellular or integral membrane proteins

Question 12

What are the cytokine receptors?

Answer 12

Immunoglobulin (Ig) family
Hemopoietic Growth Factor (type 1 and Type II) family
Interferon (type 2) family
Tumor Necrosis factors (TNF) (type 3) family
G protein-coupled receptors
Interleukin-17 receptor

Question 13

What are some cytokine characteristics?

Answer 13

Pleiotropic- same cytokine can have different target cells and receptors, with different biological outcomes
redundancy- different cytokines produce same effects

Question 14

What are the cytokine types?

Answer 14

interleukins
chemokines
TNF (Tumor Necrosis Factor)
Interferons

Question 15

Which of the following is TRUE about the action of HDAC inhibitors?
1. They decrease nucleosome mobility
2. They (indirectly) promote transcription
3. They prevent DNA methylation
4. They (indirectly) reduce protein synthesis
5. They (indirectly) decrease histone acetylation

Answer 15

2. They (indirectly) promote transcription

Question 16

Human genes with recognizable TATA boxes are most likely to be
1. regulated in response to either physiological or developmental changes, but not both
2. pseudogenes
3. regulated in response to physiological and developmental changes
4. expressed at a constant rate; “housekeeping” genes
5. regulated by the cell cycle only

Answer 16

4. expressed at a constant rate; “housekeeping” genes

Question 17

Which of the following is a difference between lysosomal and ubiquitin-mediated protein degradation?
1. Lysosomal degradation occurs only in the nucleus, but ubiquitin-mediated protein degradation occurs only in cytoplasm
2. These two processes are synonymous
3. Lysosomal degradation is the degradation of organelles whereas all proteins are degraded through ubiquitin-dependent mechanisms
4. Proteases inside the lysosome mediate lysosomal degradation whereas the proteasome is responsible for ubiquitin-mediated protein degradation
5. Ubiquitin-mediated degradation is non-selective whereas lysosomal degradation is highly specific

Answer 17

4. Proteases inside the lysosome mediate lysosomal degradation whereas the proteasome is responsible for ubiquitin-mediated protein degradation

Question 18

Which statement correctly describes the 20S proteasome?
1. Requires phosphorylation for activation
2. Has three enzyme activities: trypsin, chymotrypsin, and caspase
3. recognizes and degrades ubiquinated proteins
4. Is only expressed in the ER
5. Degrades both correctly folded and misfolded proteins

Answer 18

2. Has three enzyme activities: trypsin, chymotrypsin, and caspase

Question 19

TFIIH is a critical factor for initiating transcription. Which of the following is NOT a function of TFIIH?
1. DNA binding
2. Kinase
3. Phosphatase
4. Helicase
5. ATPase

Answer 19

3. Phosphatase