quizlet.com/896817284/cell-biology-smu-exam-2-flash-cards/

You have a mixture of 4 different proteins. Here are their properties:

Protein A: 65 kD, pI 7.8

Protein B: 125 kD, pI 6.8

Protein C: 90 kD, pI 6

Protein D: 2 subunits, both subunits are 90 kD, pI 8.5

After separating your mixture of proteins using SDS-PAGE, you identify the presence of Protein A by performing a western blot. How many bands do you see on your western blot?

a. 4 bands

b. 3 bands

c. 1 band

d. 2 bands

1 band

You have a mixture of 4 different proteins. Here are their properties:

Protein A: 65 kD, pI 7.8

Protein B: 125 kD, pI 6.8

Protein C: 90 kD, pI 6

Protein D: 2 subunits, both subunits are 90 kD, pI 8.5

If you separate these proteins by isoelectric focusing, how many bands would you see?

a. 4 bands

b. 3 bands

c. 5 bands

d. 2 bands

4 bands

Why are antibodies a good tool to use in immunoprecipitation?

A:They are divalent and can precipitate proteins out of solution.

B:All of these.

C:They can crosslink and aggregate proteins.

D:They can specifically bind to their antigen that is present within a mixture of molecules.

All of these.

Phospholipids form lipid bilayers due to the fact that

A:all of these

B:the bilayer shields the hydrocarbon tails from the aqueous environment.

C:they are cylindrical in shape.

D:they are amphipathic.

all of these

Which of the following methods requires the use of a centrifuge to obtain a protein of interest?

a. immuno-precipitation

b. immuno-affinity column chromatography

c. mass spectrometry

d. SDS-PAGE

immuno-precipitation

You have a mixture of 4 different proteins. Here are their properties:

Protein A: 65 kD, pI 7.8

Protein B: 125 kD, pI 6.8

Protein C: 90 kD, pI 6

Protein D: has 2 subunits, both subunits are 90 kD and pI 8.5

If you separate these proteins by 2D gel electrophoresis, how many dots would you see?

a. 5

b. 3

c. 6

d. 4

4

Which is a true statement when comparing sphingolipids and phosphoglycerides?

a. They both contain two hydrocarbon tails derived from fatty acids.

b. Only phosphoglycerides are found in membranes.

c. None of these

d. Only phosphoglycerides contain a glycerol derived backbone.

Only phosphoglycerides contain a glycerol derived backbone.

Which is NOT a role for cellular lipids?

a. structural

b. cell signal molecule

c. chemical energy storage

d. catalyze chemical reactions

catalyze chemical reactions

Triglycerides do NOT form lipid bilayers because

a. They are not amphipathic

b. They are not cylindrical

c. They are not hydrophobic

d. They are not conical

They are not amphipathic

Which of the following is a true statement about cholesterol?

a. All of these are true statements about cholesterol.

b. When cholesterol incorporates into membranes it increases the fluidity of the membrane.

c. In an aqueous solution, cholesterol will spontaneously aggregate to form a lipid bilayer that closes into a liposome.

d. Cholesterol reduces membrane permeability.

Cholesterol reduces membrane permeability.

Fatty acids assemble into a micelle using

a. assembly proteins.

b. covalent bonds.

c. hydrophobic forces.

d. flippase

hydrophobic forces.

Which of the following membrane lipids contains glycerol as a subunit of its molecular structure?

A:Phosphatidylethanolamine

B:Ceramide

C:Galactocerebroside

D:Cholesterol

Phosphatidylethanolamine

In what way is the Glucose Uniporter associated with the membrane?

A:multi-pass transmembrane

B:single-pass transmembrane protein

C:lipid-anchored protein

D:mono-layer associated

multi-pass transmembrane

If the backbone of a polypeptide is hydrophilic, how can a transmembrane alpha helix span the hydrophobic portion of the lipid bilayer?

a. because many transmembrane alpha helices must come together in a way that neutralizes the hydrophilic backbone

b. because the membrane bends in such a way that the polar heads of the lipids contact the transmembrane helix

c. because amino acid side chains in a transmembrane helix are hydrophobic and interact with the hydrophobic interior of the bilayer

d. because the hydrophilic backbone makes a hole in the membrane

because amino acid side chains in a transmembrane helix are hydrophobic and interact with the hydrophobic interior of the bilayer

Spectrin is an important structural component of the cell cortex. Spectrin is an example of a _____________ protein.

a. peripheral membrane

b. lipid-linked

c. monolayer-associated

d. membrane

peripheral membrane

Which mechanism best describes the process by which intestinal epithelial cells maintain apical and basolateral membrane domains?

a. Proteins are tethered to the extracellular matrix.

b. Apical proteins interact with the proteins on the surface of another cell.

c. Protein movement is limited by the presence of a diffusion barrier.

d. Proteins are tethered to the cell cortex.

Protein movement is limited by the presence of a diffusion barrier.

Which of the following is often found associated with lipid rafts in the plasma membrane?

a. red fluorescent dyes

b. sphingolipids

c. the cell cortex

d. phosophatidylserine

sphingolipids

What is required to generate a multi-pass transmembrane protein?

A:an internal ER stop-transfer signal sequence

B:an ER-membrane bound ribosome

C:a protein translocator

D:all of these answers are correct

all of these answers are correct

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?

A: plasma membrane proteins

B:all of these answers are correct

C:soluble secreted proteins

D:ER membrane proteins

all of these answers are correct

What is the name for the extensive network of cytosolic fibrous proteins that provides structural support for the plasma membrane?

A:extracellular matrix.

B:cortex

C:triskelion.

D:spectrin

If glucosylcerebroside is located on the luminal side of the Golgi membrane and then makes its way to the plasma membrane via vesicle transport, where will it then be located?

a. it will first be on the extracellular leaflet of the plasma membrane but flippase will flip it to the cytosolic leaflet

b. on the cytosolic leaflet of the plasma membrane

c. on the extracellular leaflet of the plasma membrane

d. it will first be on the cytosolic leaflet of the plasma membrane but then will be flipped by a flippase to the extracellular leaflet

on the extracellular leaflet of the plasma membrane

When a cell is undergoing programmed cell death, it will flip ____________ to its outer leaflet as a cellular signal to immune cells.

a. ceramide

b. phospatidylinositol

c. phosphatidylethanolamine

d. phosphatidylserine

phosphatidylserine

You are culturing temperature sensitive yeast mutants and would like to switch them from the permissive (lower temperature) to the non-permissive higher temperature in order to observe the mutant phenotype. Which of the following adjustments might the yeast have to make to maintain the same level of membrane fluidity?

a. decrease the amount of cholesterol in the membrane

b. produce lipids with hydrocarbon tails that are longer

c. increase the amount of cholesterol in the membrane

d. produce lipids with hydrocarbon tails that are shorter

produce lipids with hydrocarbon tails that are longer

Which of the following methods can be used to determine the lateral mobility of a protein that is found on the plasma membrane?

a. SPT

b. All of these

c. Gold-labeled Immuno EM

d. Cryo EM

SPT

Symporters allow molecules to pass through the membrane by which process?

A:facilitated diffusion

B:simple diffusion

C:active transport

D:passive transport

active transport

If you perform FRAP analysis and fluorescence recovery occurs quickly this means that...

a. Phospholipids are quickly flipping back and forth between the two leaflets.

b. There is asymmetry in the lipid bilayer.

c. The labeled protein is able to freely diffuse.

d. The labeled protein is anchored to the cell cortex.

The labeled protein is able to freely diffuse.

Which of these molecules would be the least likely to pass through the cell membrane by simple diffusion?

a. N2

b. glucose

c. H+

d. H2O

H+

Which of these molecules can pass through the cell membrane most readily by simple diffusion?

a. N2

b. H2O

c. glucose

d. H+

N2

Which of the following is true about membrane potential in animal cells?

a. It is maintained by Na+-K+ pumps

b. It is usually positive when a cell is at rest

c. It does not change

d. It does not change

It is maintained by Na+-K+ pumps

What is true about a cell at resting membrane potential?

A:The resting membrane potential is between -20 mV and -200 mV.

B:The membrane is most permeable to Na+.

C:The electrochemical potential across the membrane is zero.

D:There are more Na+ ions in the cell than outside the cell.

The resting membrane potential is between -20 mV and -200 mV.

Which of the following statements about retinal is FALSE?

A:it covalently binds to light-driven proton pumps

B:it absorbs light

C:it is a small peptide molecule

D:photons cause it to change shape

it is a small peptide molecule

ATP hydrolysis provides energy for which of the following?

A:Ca2+ pumps

B:all of these answers are correct

C:H+ pumps

D:Na+-K+ pumps

all of these answers are correct

Ouabain is a selective inhibitor of what?

a. voltage-gated Na+ and K+ channels

b. Na+-K+ pumps

c. Ca2+ pumps

d. H+ pumps

Na+-K+ pumps

Bacteriorhodopsin is an example of a:

a. voltage-gated channel

b. ligand-gated channel

c. proton pump

d. symporter

proton pump

Tight junctions perform which of the following roles?

a. they provide a small ion-selective pore in the middle of ion channels

b. they hold pre- and post-synaptic neurons together at a synapse

c. they create a seal between adjacent cells

d. they allow mixing of apical and basal membrane components

they create a seal between adjacent cells

Mechanically-gated ion channels are most likely to be found in which cell type?

a. Hensen's cells

b. gut epithelial cells

c. auditory hair cells

d. halobacteria

auditory hair cells

Which of the following statements about ion channels is correct?

a. they require ATP to open

b. they operate by active transport mechanisms

c. they exhibit "all or none" open and closed conformations

d. they have to undergo conformational changes for each ion that is passed

they exhibit "all or none" open and closed conformations

At rest, neurons have a higher membrane permeability to K+ than to Na+. Which membrane protein contributes the most to this K+ permeability?

a. K+ leak channels

b. Na+-K+ pumps

c. K+-Cl- symporter

d. voltage-gated K+ channels

K+ leak channels

Which of the following best describes the behavior of a population of voltage-gated channels exposed to their threshold potential?

A:All channels open completely.

B:Some channels remain closed and some open completely.

C:All channels open partly, each to a different degree.

D:All channels open partly, to the same degree.

Some channels remain closed and some open completely.

A patient has a gene mutation that causes a loss of function of voltage-gated Ca2+ channels at the presynaptic terminals of neurons. What is the most likely effect of this mutation?

A:impaired action potential propagation

B:impaired action potential initiation

C:impaired neurotransmitter release

D:impaired neurotransmitter release

impaired neurotransmitter release

Cardiac pacemaker cells fire action potentials that cause the heart to beat and that are independent of Na+. Using what you know about the concentration gradients for various ions, the flux of which ion is most likely to contribute to the steep depolarization phase of the action potential in cardiac pacemaker cells?

A:K+

B:Ca2+

C:Mg+

D:Cl-

Ca2+

Which of the following is not considered a component of the endomembrane system?

A:endosomes

B:mitochondria

C:endoplasmic reticulum

D:Golgi apparatus

mitochondria

A patient has a gene mutation that causes a loss of function of voltage-gated K+ channels along axons. What is the most likely effect of this mutation?

a. none of these answers are correct

b. impaired neurotransmitter release

c. impaired action potential initiation

d. impaired action potential repolarization

impaired action potential repolarization

Which of the following statements about ion channels is correct?

A:they require ATP to open

B:they operate by active transport mechanisms

C:they have to undergo conformational changes for each ion that is passed

D:they exhibit "all or none" open and closed conformations

they exhibit "all or none" open and closed conformations

Which of the following neurotransmitters always causes depolarizing postsynaptic responses?

a. glutamate

b. acetylcholine

c. GABA

d. glycine

glutamate

Channelrhodopsin is an example of a:

a. proton pump

b. light-gated channel

c. voltage-gated channel

d. ligand-gated channel

light-gated channel

Acetylcholine receptors are an example of a:

a. light-gated ion channel

b. mechanically-gated ion channel

c. voltage-gated ion channel

d. ligand-gated ion channel

ligand-gated ion channel

Release of gamma aminobutyric acid at a synapse is most likely to have what effect on the postsynaptic cell?

A:generation of an excitatory postsynaptic potential

B:activation of voltage-gated Ca2+ channels

C:influx of Cl-

D:depolarization of the membrane potential

influx of Cl-

Which of the following is a feature of the nuclear membrane?

A:it is two-layered

B:it is similar to prokaryotes

C:it may have evolved from invagination of the plasma membrane of an aerobic bacterial cell

D:it is continuous with the Golgi apparatus

it is two-layered

The closed conformation of voltage-gated Na+ channels corresponds best with which of the following?

A:hyperpolarization overshoot phase of the action potential

B:absolute refractory period of the action potential

C:the peak of the action potential

D:upstroke of the action potential

hyperpolarization overshoot phase of the action potential

Which of the following is true of non-myelinated axons?

a. they have clusters of voltage-gated Na+ channels at Nodes of Ranvier

b. they exhibit saltatory conduction

c. they conduct action potentials faster than myelinated axons of the same size

d. they utilize voltage-gated K+ channels for action potential repolarization

they utilize voltage-gated K+ channels for action potential repolarization

Which of the following is true of myelinated axons?

a. they propagate action potentials as a continuous wave

b. they have sodium channels evenly dispersed along their length

c. they exhibit saltatory conduction

d. they are insulated by myelin at Nodes of Ranvier

they exhibit saltatory conduction

Mitochondria are hypothesized to have originated when a bacterium was engulfed by a larger eukaryotic cell. Which of the following properties of mitochondria support this hypothesis?

a. they do not require oxygen to generate ATP

b. they have their own genes which bear some similarity to bacterial genes

c. they participate in vesicular traffic with the other compartments of the endomembrane system

d. they have a single membrane similar to gram-positive bacteria

they have their own genes which bear some similarity to bacterial genes

Which of the following is considered a component of the endomembrane system?

a. mitochondria

b. lysosomes

c. ribosomes

d. chloroplasts

lysosomes

Which of the following statements about nuclear pore complexes is correct?

a. they adopt a basket-like structure

b. all of these answers are correct

c. they act as bidirectional gateways for the import and export of proteins

d. they allow passage of small, water soluble molecules without nuclear localization signals

all of these answers are correct

Cytosolic proteins have which of the following characteristics?

a. they do not have a signal sequence

b. they are water insoluble

c. they can directly enter the Golgi apparatus

d. they are translated by ribosomes on the endoplasmic reticulum

they do not have a signal sequence

What is the role of the nuclear localization sequence in a nuclear protein?

A:It is a hydrophobic sequence that enables the protein to enter the nuclear membranes.

B:It prevents the protein from diffusing out of the nucleus through nuclear pores.

C:It aids in protein unfolding so that the protein can thread through nuclear pores.

D:It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

Where in the cell do proteins that are fully translated in the cytosol and lack a sorting signal end up?

A:mitochondria.

B:interior of the nucleus.

C:nuclear membrane.

D:cytosol

cytosol.

Which of the following is a property of Ran-GAP?

a. it causes Ran-GDP to release its GDP and take up GTP

b. it is exclusively localized to the nucleus

c. it converts Ran-GTP to Ran-GDP

d. it causes prospective nuclear proteins to dissociated from their nuclear import receptors

it converts Ran-GTP to Ran-GDP

Which enzyme displaces prospective nuclear proteins from their receptors, allowing the imported protein to be released?

a. Ran-GTP

b. Ran-GDP

c. Ran-GAP

d. Ran-GEF

Ran-GTP

Which of the following is not necessary for nuclear import of a protein?

a. GTP hydrolysis

b. a protein translocator

c. a nuclear import receptor

d. a nuclear localization signal

a protein translocator