Snapps week 3

Question 1

Ryanodine receptors serve to

Answer 1

move Ca from ER/SR lumen into the cytoplasm

causing release of free Ca into the cytosol from intracellular stores

Question 2

Depletion of Ca from the ER causes:

Answer 2

Store-operated channels at the PM to become activated

Question 3

Ryr and IP3 let Calcium

Answer 3

out of the ER/SR only

Question 4

Binding of Ca causes C2 domains to:

Answer 4

associate with plasma membrane

Synaptotagmin (has 2 C2 domains) is in vesicles is triggered by Ca to do exocytosis PKC translocates to the membrane in presence of Ca

Question 5

Which of the following has an EF hand motif ?

Answer 5

calmodulin

Question 6

Synaptotagmin and PKC have _____domains

Answer 6

C2

causes association to the PM

Question 7

Which of the following correctly describes Calmodulin?

Answer 7

1. a strongly conserved Ca effector that contains 4 EF hand motifs
2. many downstream targets

Question 8

Which of the following Ca effectors confers Ca regulation to proteins, ion channels, kinases, phosphatases and cyclic nucleotide phosphodiesterases?

Answer 8

calmodulin

Question 9

which of the following correctly describes endocrine signaling?

Answer 9

long reaching signals that used a bloodstream for transport

Question 10

Synaptic signaling:

Answer 10

(nervous system, long reaching, high localization/precision, synapse onto target receptors on PM)

Question 11

Paracrine signaling

Answer 11

signals act on neighboring cells

Question 12

Contact-Dependent signaling: (immune response. cells must touch to relay signal)

Answer 12

immune response. cells must touch to relay signal

Question 13

Which of the following signaling mechanisms requires a receptor on the plasma membrane of its target cell in order to transduce a signal?

Answer 13

water soluble peptides

Question 14

How do phosphodiesterases contribute to signal termination?

Answer 14

the reuptake extracellular signaling molecules

Question 15

When G-proteins are bound to GTP they are:

Answer 15

ON

Question 16

In the absence of hydrophobic hormones, nuclear receptors are usually

Answer 16

bound to inhibitory proteins

Question 17

A mutation in which of the following receptors would interfere with Vitamin D absorption?

Answer 17

ion channel linked

Question 18

Which of the following is a true characteristic about steroids?

Answer 18

permeate cell membranes

act on intracellular targets

Question 19

What causes the positive end of a microtubule to stop growing and suddenly shrink?

Answer 19

Loss of GTP rich cap

Question 20

Choose the correct mechanism of the drug Colchicine:

Answer 20

enhances microtubule poly

Question 21

Which of the following is a result of GTP binding to microtubules?

Answer 21

an increase in stability which promotes polymerization at positive end

GTP binding does not use energy

Question 22

which is more stable, GTP or GDP?

Answer 22

GTP is more stable

Question 23

The mitotic spindle is constructed from microtubules and serves to segregate the replicated chromosomes during mitosis. Choose the correct sequence of events that makes this possible.

Answer 23

Dynein motor proteins bind to MTs and move towards the centrosome (towards negative ends) to separate chromosomes

Question 24

Stress fibers and focal adhesions are formed by activation of which Ras GTPase?

Answer 24

Rho

Question 25

Rho GTPase function:

Answer 25

makes stress fibers and focal adhesions Rac forms veils (lamellopodia) Cdc42 forms filopodia

Question 26

During mitosis, which of the following functions is carried out by actin?

Answer 26

Cleave the cell into two halves when sufficient tension is present

Question 27

Epidermolysis bullosa simplex is a disorder causing the epidermis to be extremely sensitive to mechanical stress and susceptible to blister formation. This disorder results from a mutation that interferes with the assembly of:

Answer 27

keratin

Question 28

Phalloidin is a poison extracted from the death cap mushroom. What is the function of Phalloidin?

Answer 28

Binds and stabilizes F-actin causing actin polymerization

Question 29

Receptor Tyrosine Kinase activation is driven by which of the following?

Answer 29

dimerization leading to phosphorylation

Question 30

Which of the following is the key downstream signaling event that results from the activation of Epidermal Growth Factor Receptors?

Answer 30

Ras activation

Question 31

Which of the following correctly describes the mechanism by which anti-epidermal growth factor receptor antibodies downregulate Ras expression in tumor cells?

Answer 31

block ligand binding to tyrosine kinase receptors, preventing dimerization

Question 32

Which of the following correctly describes the mechanism by which tyrosine kinase small molecule inhibitors downregulate Ras expression in tumor cells?

Answer 32

bind tyrosine kinase in its substrate binding site inside of cells, preventing ATP binding

Question 33

Elevated epidermal growth factors or elevated signaling from these receptors is associated with poor prognosis in cancer patients and is used to select patients for EGFR inhibitor therapy. Which of the following would provide a resistance mechanism to these drugs?

Answer 33

1. Selection for tumor cells with a second site mutation in epidermal growth factor receptor that prevents inhibitor binding?
2. Activation of Ras by mutation?
3. Activation of other receptor tyrosine kinases

Question 34

Which of the following is the major reaction facilitated by kinases?

Answer 34

phosphorylation

Question 35

Which of the following functional groups distinguishes Serine, Threonine and Tyrosine from other amino acids?

Answer 35

hydroxyl

Question 36

Why is Ca2+ considered the most extensive node in signaling?

Answer 36

it represents a point in a larger network with multiple inputs and outputs

Question 37

How do phosphodiesterases contribute to signal termination?

Answer 37

hydrolyze cAMP to cGMP

Question 38

What is the primary consequence of cooperative substrate binding for an enzyme?

Answer 38

increased sensitivity of the reaction velocity to the substrate concentration. b. non-catalytic binding sites help increase affinity at catalytic sites