Exam 1

Question 1

The active form of which of the following will increase the likelihood that a monomeric GTPase is bound to its effector?
-GAP
-GEF
-GDI
-Two of the above

Answer 1

GEF

Question 2

You have discovered a new fluorophore that emits yellow light when excited. It is more likely that the color of the excitation light is ___ because the excitation wavelength must have ___ energy than its emission wavelength
-green; less
-red;less
-green;more
-red;more

Answer 2

Green; more

Question 3

Which of the following is a mechanism to decrease the concentration of free Ca2+ in the cytoplasm?
1. The Orai/STIM pathway
2. Ca2+ ATPase in the ER membrane
3. Ca2+ ATPase in the plasma membrane

Answer 3

2 and 3 only

Question 4

Vascular Endothelial Growth Factor (VEGF) binds to the VEGF receptor, which is a tyrosine kinase receptor. This induces the activation of the receptor and the recruitment and activation of a kinase on the cytoplasmic side of the membrane. This kinase phosphorylation transcription factors that induce cellular proliferation. In this example ___ is the ligand and ___ is/are the transducer

Answer 4

VEGF; kinase

Question 5

Which of the following is an advantage of fluorescence microscopy over light microscopy?
-Greater Contrast
-Greater Resolution
-The ability to see live (not dead) specimens
-Two of the above
-All of the above

Answer 5

Greater Contrast

Question 6

PIP3 is a byproduct of a reaction involving which lipid?

Answer 6

Phosphotidylinositol

Question 7

If a kinase activates a protein, which type of enzyme is likely to deactivate it?

Answer 7

Phosphatase

Question 8

Which phosphoglyceride found in the plasma membrane also serves as a signaling molecule

Answer 8

Phosphatidylinositol

Question 9

Which of the following events is the result of the activation of a seven-helix receptor?
-Conformation change of TM5 and TM6
-Recruitment of a heterotrimeric G-protein
-Release of GDP and binding of GTP by the alpha-subunit
-Two of the above
-All of the above

Answer 9

All of the above

Question 10

Which is the slowest (rate-limiting) step in the monomeric GTPase cycle in the absence of external influence?

Answer 10

Release of GDP

Question 11

Today in lecture we will discuss DNA winding around his tones. Based on your knowledge of molecular scale, what rage of measurements would we use to determine the size of these structures

Answer 11

Nanometers

Question 12

Which of the following is NOT a mechanism to inhibit kinase activity?
-Extrinsic regulation by a pseudo substrate
-Phosphorylation
-Intrinsic regulation by a pseudo substrate
-Changes in localization (i.e targeting)
-All of the above are mechanisms to inhibit a kinase

Answer 12

All of the above are mechanisms to inhibit a kinase

Question 13

Your patient has a mutation in the cyclooxygenase gene such that the enzyme is inactive. What will she likely have trouble producing?

Answer 13

Diacylglycerol

Question 14

You identify a novel protein and find that the amino acid sequence has a continuous stretch of 14 amino acids that are lipophilic. Based on this information, you might predict that this is a ___ protein

Answer 14

Transmembrane

Question 15

Which receptor has both a transmembrane and cytoplasmic form?

Answer 15

Guanylyl cyclase receptors

Question 16

Which of the following is a DISADVANTAGE of light microscopy?
-You can only create contrast in dead cells
-It cannot be used to resolve organelles from the rest of the cell
-Most cells and tissues are transparent, so methods are necessary to create contrast
-Two of the above
-All of the above

Answer 16

Most cells and tissues are transparent, so methods are necessary to create contrast

Question 17

You have just finished sequencing the genome of a new organism and you become interested in a protein that has a pleckstrin homology (PH) domain. What do you think it might interact with?

Answer 17

Polyphosphoinositides

Question 18

Which of the following would you NOT expect to find in the plasma membrane?
-Cholesterol
-Protein
-Glycerophspholipids
-Sphingolipids
-All of the above would be found in the plasma membrane

Answer 18

All of the above would be found in the plasma membrane

Question 19

Regulated receptor dimerization induced by ligand dimmers, the relief of auto inhibition, or conformation changes of a preformed dimmer are indicative of which receptor family?

Answer 19

Receptor tyrosine kinases

Question 20

If you have two fatty acids and a choline, what additional molecules would you need to make a lipid commonly found in the plasma membrane?
-Another fatty acid
-Glycerol
-Phosphate
-Two of the above
-All of the above

Answer 20

Two of the above

Question 21

A hydropathy plot would be useful to predict the probability that a protein ___

Answer 21

Has a transmembrane domain

Question 22

You identify a new fatty acid that can either have two double bonds or no double bonds. The form that has no double bonds is said to be ____ and is more likely to be a ____ at room temperature

Answer 22

Saturated; solid

Question 23

If I have a glycerophospholipid, which enzyme would I need to activate in order t o generate arachadonic acid?

Answer 23

Phospholipase A2

Question 24

To make a ganglioside, you would need:

Answer 24

Ceramide and a complex carbohydrate containing Salic acid

Question 25

You become interested in a protein whose amino acid sequence contains the consensus sequence for protein kinase X, except that it has alanine instead of a tyrosine. What do you expect your protein might have the ability to do?

Answer 25

Inhibit protein kinase x