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Cell Biology - Exam Two Answer Key | PCB 4023, Exams of Cell Biology

Material Type: Exam; Professor: Kim; Class: Cell Biology; Subject: Process Biology; University: Florida International University; Term: Summer 2015;

Typology: Exams

2015/2016

Uploaded on 06/02/2016

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Which of the following molecules does not contain a fatty acid tail? SDS or CHOLESTEROL
Which of the following statements is true? (a) Phospholipids will spontaneously form liposomes
in POLAR solvents. Or MEMBRANE LIPIDS DIFFUSE WITHIN THE PLANE OF THE MEMBRANE
You got a cell line with no name, but it says that this cell line forms coated pits but vesicle
budding and the removal of coat proteins don’t happen. Which of the following proteins might
be lacking in this cell line? DYNAMIN
Bacterial porin proteins form large, barrel-like channels in the membrane. Which of the
following is true about these channels? They are made primarily of β-sheets----------------------
NOT true? They are primarily made of a helices
The endothelial cells found closest to the site of an infection express proteins called _____,
which binds to a particular __________that is presented on the surface of a target cell. LECTIN
AND OLIGOSACCHARIDE
The extracellular side of the integral membrane proteins is often glycosylated. (a) True
The cytoplasmic side of the integral membrane proteins are often glycosylated False
Cholesterol equally locates to the outer and inner leaflets of the plasma membrane. (a) True
Cholesterol is more enriched at the outer leaflet of the plasma membrane False
Inner leaflet of the plasma membrane is enriched with glycolipids False
Which of the following proteins is a GTP binding protein? Rab
Transmembrane proteins cross the plasma membrane as an unfolded polypeptide. False
Membrane proteins that pump ions in and out of the cell are classified as enzymes. True
A symport would function as an antiport if its orientation in the membrane were reversed.False
The lateral motility of membrane proteins can be restricted by gap junctions. False
An electrical signal is converted into a chemical signal at the synapse by a stress gated chloride
channel. False
The resting membrane potential of animal cells is always 60 mV False
A voltage-gated Na+ channel adopts three alternative conformations. True
A voltage gated Na+ channel adopts two alternative conformations False
Tight junction permits selective ion transport. False
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Which of the following molecules does not contain a fatty acid tail? SDS or CHOLESTEROL Which of the following statements is true? (a) Phospholipids will spontaneously form liposomes in POLAR solvents. Or MEMBRANE LIPIDS DIFFUSE WITHIN THE PLANE OF THE MEMBRANE You got a cell line with no name, but it says that this cell line forms coated pits but vesicle budding and the removal of coat proteins don’t happen. Which of the following proteins might be lacking in this cell line? DYNAMIN Bacterial porin proteins form large, barrel-like channels in the membrane. Which of the following is true about these channels? They are made primarily of β-sheets---------------------- NOT true? They are primarily made of a helices The endothelial cells found closest to the site of an infection express proteins called _____, which binds to a particular __________that is presented on the surface of a target cell. LECTIN AND OLIGOSACCHARIDE The extracellular side of the integral membrane proteins is often glycosylated. (a) True The cytoplasmic side of the integral membrane proteins are often glycosylated False Cholesterol equally locates to the outer and inner leaflets of the plasma membrane. (a) True Cholesterol is more enriched at the outer leaflet of the plasma membrane False Inner leaflet of the plasma membrane is enriched with glycolipids False Which of the following proteins is a GTP binding protein? Rab Transmembrane proteins cross the plasma membrane as an unfolded polypeptide. False Membrane proteins that pump ions in and out of the cell are classified as enzymes. True A symport would function as an antiport if its orientation in the membrane were reversed.False The lateral motility of membrane proteins can be restricted by gap junctions. False An electrical signal is converted into a chemical signal at the synapse by a stress gated chloride channel. False The resting membrane potential of animal cells is always 60 mV False A voltage-gated Na+ channel adopts three alternative conformations. True A voltage gated Na+ channel adopts two alternative conformations False Tight junction permits selective ion transport. False

Calcium channel is open during hyperpolarization step. False A protein that relies on protein–protein interactions to stabilize its membrane association is classified as a peripheral membrane protein because it can be dissociated without the use of Triton X-100. (a) True Membrane synthesis in the cell requires the regulation of growth for both halves of the bilayer and the selective retention of certain types of lipids on one side or the other. Which group of enzymes accomplishes both of these tasks? (a) flippases Which of the following is required for the secretion of neurotransmitters in response to an action potential? voltage-gated Ca2+ channels Both excitatory and inhibitory neurons form junctions with muscles. By what mechanism do inhibitory neurotransmitters prevent the postsynaptic cell from firing an action potential? By opening Cl- channels Transporters, in contrast to channels, work by _____. (a). specific binding to solutes Which of the following best describes the behavior of a gated channel? It opens more frequently in response to a given stimulus The stimulation of auditory nerves depends on the opening and closing of channels in the auditory hair cells. Which type of gating mechanism do these cells use? STRESS-GATED Active transport requires the input of energy into a system so as to move solutes against their electrochemical and concentration gradients. Which of the following is one of the common ways to perform active transport? Na+-coupled …Which of the following is NOT one of the common ways to perform active transport? K+ coupled Assume that this membrane vesicle is in the cytoplasm of a cell. Proteins destined to go the extracellular space can interact with: (a) N-terminus Proteins destined to go the lysosomal lumen can interact with N terminus This membrane vesicle will undergo fusion with the plasma membrane. After the event of fusion, proteins in the cytoplasmic side can interact with: C-terminus This membrane vesicle will undergo fusion with the lysosome. After the event of fusion, proteins

Indicate which of the following is false. Action potentials are usually mediated by

voltage-gated Ca2+ channels

Ca2+ pumps in the plasma membrane and ER are important for preventing Ca2+ from

altering the activity of molecules in the cytosol

K+ leak channels are found in the plasma membrane. What do they accomplish in a

resting cell? They keep the electrochemical gradients for K+ at zero

Which of the following statements about the endoplasmic reticulum (ER) is TRUE?

The proteins in the lumen of the ER will be easily oxidized

OXIDIZED AND ROUGH ER=TRUE

Which of the following statements about the endoplasmic reticulum (ER) is false?

(d) The proteins in the lumen of ER will be easily reduced.

OR PROTEINS TO BE DELIVERED TO THE ER LUMEN ARE SYNTHESIZED ON THE

SMOOTH ER

Which of the following statements is true? Most mitochondrial proteins are imported

from the cytosol. (…but are synthesized in the mitochondria)

Which of the following statements about membrane enclosed organelles is true? In a

typical cell the area of the ER membrane far exceeds the area of the plasma membrane

After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you

purify the RNAs attached to it. Which of the following proteins do you expect the RNA

from the rough endoplasmic reticulum to encode? (c) proteins with the signal peptide

OR ALL OF THE ABOVE (SOLUBLE SECRETED PROTEINS, ER MEMBRANE

PROTEINS, PLASMA MEMBRANE PROTEINS)

OR NONE OF THE ABOVE (SOLUBLE CYTOPLASMIC PROTEINS, NUCLEAR

PROTEINS, PERIPHERAL MEMBRANE PROTEINS BOUND TO THE CYTOPLASMIC)

Which of the following choices reflects the appropriate order through which a membrane

receptor protein destined to travel a lysosome? plasma membrane → endosome →

lysosome

Which of the following statements about vesicle budding from the Golgi is true ?Clathrin

molecules act both at the cytosolic surface of the Golgi membrane and the plasma

membrane.

Which of the following statements about vesicle budding from the Golgi is FALSE?

Clathrin molecules are important for binding and selecting cargos for transport

What is the role of the nuclear localization sequence in a nuclear protein?(a) It is bound

by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

Which of the following statements is true? Membrane lipids diffuse within the plane of the membrane Which does NOT occur spontaneously in biological membrane? Switching between lipid layers Which of the following protein families are NOT involved in directing transport vesicles to the target membrane? ADAPTINS