Exam 3

Question 1

! Which is NOT the reason why all living cells must carefully regulate the fluidity of their membranes?

A. to ensure that membrane molecules are distributed evenly between daughter cells when a cell divides
B. all of the above
C. to permit membrane lipids and proteins to diffuse from their site of synthesis to other regions of the cell
D. to constrain and confine the movement of proteins within the membrane bilayer
E. to allow membranes, under appropriate conditions, to fuse with one another and mix their molecules

Answer 1

D. to constrain and confine the movement of proteins within the membrane bilayer

Question 2

BIO329 students hope to probe how membrane fluidity affects electron transport chain activity and ATP production in bacterial cells by manipulating membrane fluidity and measuring respiration. How could they increase membrane fluidity?

A. none of the above
B. increase the amount of cholesterol present in the bacterial membranes
C. increase the length of the fatty acid tails in phospholipids
D. decrease the temperature of the media the cells are grown in
E. increase the proportion of phospholipids with unsaturated fatty acids

Answer 2

E. increase the proportion of phospholipids with unsaturated fatty acids

Question 3

Plasma membrane is not involved in which of the following?

A. cell recognition
B. cell signaling
C. import & export of nutrients & wastes
D. cell growth & motility
E. ribosome translation

Answer 3

E. ribosome translation

Question 4

What type of protein moves randomly selected phospholipids from one monolayer of a lipid bilayer to the other?

A. none; phospholipids cannot move from one monolayer to another
B. scramblase
C. phospholipase
D. none; such movement occurs spontaneously and relatively quickly
E. flippase

Answer 4

B. scramblase

Question 5

When a vesicle (leaving the cell) fuses with the plasma membrane, which way will the monolayer that was exposed to the interior of the vesicle face?

A. the endomembrane system
B. It depends on where, along the plasma membrane, the vesicle fuses.
C. The direction the monolayer will face will be established randomly.
D. the cell exterior
E. the cell cytoplasm

Answer 5

D. the cell exterior

Question 6

Which of the following is a function of proteins in the plasma membrane?

A. allow specific ions to cross the plasma membrane, thereby controlling its electrical properties
B. transmit extracellular signals to the cell interior
C. all of the above
D. serve as anchors to attach the cell to the extracellular matrix
E. transport molecules across the membrane

Answer 6

C. all of the above

Question 7

The shape of a cell and the mechanical properties of its plasma membrane are determined by a meshwork of fibrous proteins called what?

A. lamellipodium
B. glycocalyx
C. basal lamina
D. tight junction
E. cell cortex

Answer 7

E. cell cortex

Question 8

Which is a mechanism for restricting the movement of proteins in the plasma membrane?

A. using barriers such as tight junctions
B. tethering proteins to the surface of another cell
C. tethering proteins to the extracellular matrix
D. all of the above
E. tethering proteins to the cell cortex

Answer 8

D. all of the above

Question 9

What function is served by the carbohydrates attached to cell-surface proteins?

A. all of the above
B. protect the cell from mechanical and chemical damage
C. establish a distinctive identity for cell-cell recognition
D. lubricate cells to keep them from sticking together
E. promote cell-cell adhesion

Answer 9

A. all of the above

Question 10

Red blood cells have been very useful in the study of membranes and the protein components that provide structural support. Which of the following proteins is the principal fibrous protein in the cortex of the red blood cell?

A. actin
B. attachment proteins
C. spectrin
D. tubulin
E. dynamin

Answer 10

C. spectrin

Question 11

Which of the following statements about the carbohydrate coating of the cell surface is FALSE?

A. Specific oligosaccharides can be involved in cell-cell recognition.
B. It is not usually found on the cytosolic side of the membrane.
C. The arrangement of the oligosaccharide side chains is highly ordered, much like the peptide bonds of a polypeptide chain.
D. None of the above
E. It can play a role in cell-cell adhesion.

Answer 11

C. The arrangement of the oligosaccharide side chains is highly ordered, much like the peptide bonds of a polypeptide chain.

Question 12

Which mechanism best describes the process by which neutrophils are recruited by endothelial cells?

A. all of the above
B. Proteins are tethered to the extracellular matrix.
C. Proteins are tethered to the cell cortex.
D. Proteins interact with the proteins on the surface of another cell.
E. Protein movement is limited by the presence of a diffusion barrier.

Answer 12

D. Proteins interact with the proteins on the surface of another cell.

Question 13

How do transporters and channels select which solutes they help move across the membrane?

A. Channels discriminate between solutes mainly on the basis of size and electric charge; transporters bind their solutes with great specificity in the same way an enzyme binds it substrate.
B. Transporters discriminate between solutes mainly on the basis of size and electric charge; channels binds their solutes with great specificity in the same way that an enzyme binds it substrate.
C. Channels will allow the passage of any solute as long as it has an electrical charge; transporters bind their solutes with great specificity in the same way an enzyme binds its substrate.
D. Channels allow the passage of solutes that are electrically charged; transporters facilitate the passage of molecules that are uncharged.
E. Both channels and transporters discriminate between solutes mainly on the basis of size and electric charge.

Answer 13

A. Channels discriminate between solutes mainly on the basis of size and electric charge; transporters bind their solutes with great specificity in the same way an enzyme binds it substrate.

Question 14

Most sports drinks contain both carbohydrates and salts. The carbohydrates replace glucose burned during exercise and the salts replace salts lost in sweat. The salt also helps the small intestine absorb glucose. Pick the answer that accurately describes which salt is most beneficial to for glucose absorption
Q 15 of Bio 329 Exam 3 for diagram

A. I don’t like sports drinks.
B. KCl, because Cl is needed for glucose entry.
C. KCl, because K+ is needed for glucose entry.
D. NaCl, because Na+ is needed for glucose entry.
E. HCl, because H+ is needed for glucose entry.

Answer 14

D. NaCl, because Na+ is needed for glucose entry.

Question 15

Which of the following describes the resting membrane potential of a neuron?

A. a voltage difference across the plasma membrane when the neuron has been stimulated
B. a voltage difference of 0 millivolts (mV) across the membrane
C. a voltage difference that is chiefly a reflection of the electrochemical Na+ gradient across the plasma membrane
D. a voltage difference across the plasma membrane, with more positive membrane potential inside
E. a state in which the flow of positive and negative ions across the plasma membrane is precisely balanced

Answer 15

E. a state in which the flow of positive and negative ions across the plasma membrane is precisely balanced

Question 16

Which of the following inhibits inorganic ions, such as Na+ and Cl, from passing through a lipid bilayer?

A. the watery environment on either side of the lipid bilayer
B. the ions’ large size
C. the hydrophobic interior of the lipid bilayer
D. the carbohydrate layer on the surface of the lipid bilayer
E. the hydrophobic exterior of the lipid bilaery

Answer 16

C. the hydrophobic interior of the lipid bilayer

Question 17

Which of the following statements is true?

A. Na+ is the most plentiful positively charged ion outside the cell, while K+ is the most plentiful inside.
B. K+ and Na+ are both maintained at high concentrations inside the cell compared to out.
C. K+ is the most plentiful positively charged ion outside the cell, while Na+ is the most plentiful inside.
D. K+ and Na+ are both excluded from cells.
E. K+ and Na+ are present in the same concentration on both sides of the plasma membrane.

Answer 17

A. Na+ is the most plentiful positively charged ion outside the cell, while K+ is the most plentiful inside.

Question 18

When glucose moves across a phospholipid bilayer by passive transport, which factor determines the direction of its transport?

A. the amount of energy available to fuel the transport process
B. the amount of ATP available in the cell
C. the concentrations of glucose on either side of the membrane
d. the charge difference across the membrane
E. whether the cell is metabolically active or not

Answer 18

C. the concentrations of glucose on either side of the membrane

Question 19

In passive transport, the net movement of a charged solute across the membrane is determined by which of the following?

A. the membrane potential
B. its electrochemical gradient
C. the amount of ATP available in the cell
D. its concentration gradient
E. its osmotic gradient alone

Answer 19

B. its electrochemical gradient

Question 20

Which of the following correctly describes osmosis?

A. the movement of water from an area of low water concentration to an area of high water concentration
B. the movement of water from an area of low solute concentration to an area of high solute concentration
C. the movement of water from an area of high solute concentration to an area of low solute concentration
D. all of the above
E. the movement of water from an area of low solvent concentration to an area of high solvent concentration

Answer 20

B. the movement of water from an area of low solute concentration to an area of high solute concentration

Question 21

Which of the following accurately describes the role of the Na+ - K+ pump?

A. It equilibrates the concentrations of Na+ and K+ across the plasma membrane.
B. it maintains a lower Na+ concentration outside the cell.
C. It mediates passive transport of Na+ and K+.
D. It maintains a higher K+ concentration outside the cell.
E. It maintains a higher Na+ concentration outside the cell.

Answer 21

E. It maintains a higher Na+ concentration outside the cell

Question 22

Which organelle is important for controlling the concentration of calcium ions in the cytosol?

A. Golgi apparatus
B. lysosome
C. nucleus
D. calmodulin
E. endoplasmic reticulum

Answer 22

E. endoplasmic reticulum

Question 23

The epithelial cells that line the gut have glucose Na+ symport proteins that actively take up glucose from the lumen of the gut after a meal, creating a high glucose concentration in the cytosol. How do these cells release that glucose for use by other tissues in the body?

A. The cells have glucose channels in their plasma membrane.
B. The cells have a glucose pump that expels the glucose needed by other tissues.
C. The cells run the glucose Na+ symport proteins in reverse.
D. Glucose diffuses down its concentration gradient through the lipid bilayer of the plasma membrane.
E. The cells have glucose uniports in their plasma membrane.

Answer 23

E. The cells have glucose uniports in their plasma membrane.

Question 24

When Na+ channels are opened in an animal cell, what happens to the membrane potential?

A. It stays the same.
B. It disappears, and membrane potential stabilizes at 0 mV.
C. It rapidly reaches the resting membrane potential.
D. It becomes more negative inside the cell.
E. It becomes less negative inside the cell.

Answer 24

E. It becomes less negative inside the cell.

Question 25

After the depolarization phase of an action potential, the resting potential is restored by ___-.

A. voltage-gated potassium channels opening and sodium channels inactivating
B. none of the above
C. the opening of more voltage-gated sodium channels
D. a brief inhibition of the sodium-potassium pump
E. a decrease in the membrane’s permeability to potassium and chloride ions

Answer 25

A. voltage-gated potassium channels opening and sodium channels inactivating

Question 26

Which type of ion channel plays the major role in propagating electrical signals in nerve cells?

A. mechanically-gated
B. ligand-gated
C. squid-gated
D. voltage-gated
E. star-gated

Answer 26

D. voltage-gated

Question 27

During an action potential, which of the following actions does not help return the membrane to its resting potential?

A. the flow of K+ through K+ leak channels
B. the opening of voltage-gated Na+ channels
C. the opening of voltage-gated K+ channels
D. all of the above
E. the inactivation of voltage-gated Na+ channels

Answer 27

B. the opening of voltage-gated Na+ channels

Question 28

Kaci is confused about the action of neurotransmitter. Which of the following is required for the secretion of neurotransmitters in response to an action potential?

A. Kaci, why did you send this question to Da-Sung? I don't know the answer.
B. Na+ - K+ pumps
voltage-gated K+ channels
D. neurotransmitter receptors
E. voltage-gated Ca2+ channels

Answer 28

E. voltage-gated Ca2+ channels

Question 29

Channelrhodopsin can be used for optogenetics to manipulate the activity of neurons for what reason?

A. Channelrhodopsin and neurons both sensitive to light.
B. Channelrhodopsin, when activated by light, polarizes the membrane and stimulates neurons.
C. Channelrhodopsin opens in response to neurotransmitters.
D. Channelrhodopsin, when activated light, depolarizes the membrane and stimulates neurons.
E. Channelrhodopsin is a natural component of excitatory neurons.

Answer 29

D. Channelrhodopsin, when activated by light, depolarizes the membrane and stimulates neurons.

Question 30

The correct order of passage of materials produced in a biosynthetic pathway is:

A. endoplasmic reticulum, Golgi complex, plasma membrane, secretory vesicle
B. it does not matter as it is determined by local concentration
C. endoplasmic reticulum, lysosome, Golgi complex, plasma membrane
D. endoplasmic reticulum, lysosome, secretory vesicle, plasma membrane
E. endoplasmic reticulum, Golgi complex, secretory vesicle, plasma membrane

Answer 30

E. endoplasmic reticulum, Golgi complex, secretory vesicle, plasma membrane

Question 31

! When and where is the asymmetry of the phospholipid bilayers initially established?

A. all of these is correct
B. in the secretory vesicles during lipid and protein modification
C. in the mitochondria by random insertion into the membranes
D. in the ER during lipid and protein synthesis
E. in the Golgi complex during lipid and protein modification

Answer 31

D. in the ER during lipid and protein synthesis

Question 32

How do the interiors of the ER, Golgi apparatus, endosomes, and lysosomes communicate with each other?

A. They do not communicate with one another.
B. by small vesicles that bud off of one organelle and fuse with another
C. by excreting hormones and other small signaling molecules
D. by fusing with one another
E. by open pores that allow ions to exit and enter the organelles

Answer 32

B. by small vesicles that bud off of one organelle and fuse with another

Question 33

Which of the following statements about the protein quality control system in the ER is FALSE?

A. all of the above
B. A chaperon protein will bind to a misfolded protein to retain it in the ER.
C. Proteins that are misfolded are degraded in the ER lumen.
D. Chaperon proteins help misfolded proteins foldproperly.
E. Protein complexes are checked for proper assembly before they can exit the ER.

Answer 33

C. Proteins that are misfolded are degraded in the ER lumen.

Question 34

Which of the following statements is TRUE?

A. none of the above
B. Because bacteria do not have mitochondria, they cannot produce ATP in a membrane-dependent fashion.
C. The nuclear membrane is thought to have arisen from the plasma membrane invaginating around the DNA.
D. Lysosomes are believed to have originated from the engulfment of bacteria specialized for digestion.
E. Chloroplasts and mitochondria share their DNA.

Answer 34

C. The nuclear membrane is thought to have arisen from the plasma membrane invaginating around the DNA.

Question 35

If a signal sequence is removed from an ER protein, what happens to the altered protein?

A. It is immediately degraded.
B. It can enter any organelle other than the ER.
C. It is escorted to the ER by chaperon proteins.
D. It remains in the cytosol.
E. It is unable to exit the ER.

Answer 35

D. It remains in the cytosol.

Question 36

Which is true of ribosomes?

A. A special class of ribosomes attached to the ER membrane translates the proteins destined for that organelle.
B. Polyribosomes translate only cytosolic proteins.
C. Polyribosomes translate only those proteins that have an ER signal sequence.
D. All ribosomes are attached to the ER when they begin synthesizing a protein.
E. A common pool of ribosomes is used to synthesize both cytosolic proteins and proteins destined for the ER.

Answer 36

E. A common pool of ribosomes is used to synthesize both cytosolic proteins and proteins destined for the ER.

Question 37

The ER signal sequence on a growing polypeptide chain is recognized by a signal-recognition particle (SRP) in the cytosol. What does this interaction accomplish?

A. It cleaves the ER signal sequence from the polypeptide chain.
B. It releases the polypeptide chain from the ribosome.
C. It speeds the synthesis of the polypeptide chain.
D. It guides the ribosome and its polypeptide to the ER.
E. It returns the ribosome to the pool of free ribosomes in the cytosol.

Answer 37

D. It guides the ribosome and its polypeptide to the ER.

Question 38

Which proteins play a central role in the fusion of a vesicle with a target membrane?

A. adaptin
B. tethering proteins
C. Rab rptoeins
D. clathrin
E. SNAREs

Answer 38

E. SNAREs

Question 39

Signal sequences that direct proteins to the correct compartment are

A. added to a protein by a protein translocator
B. added to proteins through post-translational modification
C. encoded in the amino acid sequence and both required and sufficient for targeting a protein to its correct destination
D random like my GPA
E. always removed once a protein is at the correct destination

Answer 39

C. encoded in the amino acid sequence and both required and sufficient for targeting a protein to its correct destination

Question 40

Phagocytosis is a process by which cells do which of the following?

A. engage in receptor-mediated endocytosis
B. secrete hormones and neurotransmitters
C. consume large particles, such as microbes and cell debris
D. ingest extracellular fluid and macromolecules
E. digest their own worn-out organelles

Answer 40

C. consume large particles, such as microbes and cell debris

Question 41

What happens to the final products of the digestion of macromolecules?

A. They are expelled from the lysosome by H+ pumps in the lysosomal membrane.
B. They are transferred to the cytosol through transporters in the lysosomal membrane.
C. They are removed from the lysosome by transport vesicles that carry them to where they are needed.
D. They are ultimately destroyed by lysosomal enzymes.
E. They are secreted from the cell when lysosomes fuse with the plasma membrane.

Answer 41

B. They are transferred to the cytosol through transporters in the lysosomal membrane.

Question 42

Nuclear pores restrict larger molecules from traversing the membrane due to their

A. very small pore size.
B. GTP hydrolysis
C. interwoven meshwork of protein fibrils
D. double membrane
E. hydrophobic interior

Answer 42

C. interwoven meshwork of protein fibrils

Question 43

A single-pass transmembrane protein destined for one of the organelles in the endomembrane system would be marked by what type of signal sequence?

A. an internal ER signal sequence
B. a cleaved internal peptide sequence
C. a cleaved N-terminal ER signal sequence and an internal stop-transfer sequence
D. a cleaved N-terminal ER signal sequence
E. an internal ER signal sequence & an internal stop-transfer sequence

Answer 43

C. a cleaved N-terminal ER signal sequence and an internal stop-transfer sequence

Question 44

Which of the following is a difference between exocytic and endocytic pathways?

A. Endocytic pathways bring soluble proteins only, whereas exocytic pathways move both soluble proteins and membrane-bound proteins.
B. Exocytic pathways often start with synthesis of proteins, whereas endocytic pathways involve breaking down macromolecules like proteins.
C. Endocytic pathways transfer proteins to the Golgi apparatus, whereas exocytic pathways transfer proteins from the Golgi.
D. none of the above
E. Exocytic pathways utilize transport vesicles, whereas endocytic pathways use only endosomes.

Answer 44

B. Exocytic pathways often start with synthesis of proteins, whereas endocytic pathways involve breaking down macromolecules like proteins.

Question 45

How do clathrin-coated vesicles select their cargo molecules?

A. Cargo is selected randomly by adaption and is sorted later in the endosomes.
B. Our local carbo company UPS is responsible.
C. Specific cargo molecules have a high affinity for adaptin.
D. Cargo is actively transported into preformed clathrin-coated vesicles through adaption.
E. Cargo receptors bind specifically to cargo proteins and to clathrin through adaptin.

Answer 45

E. Cargo receptors bind specifically to cargo proteins and to clathrin through adaptin.

Question 46

What is one of the main differences in the behavior of the proteins in a vesicle destined for constitutive secretion, and the proteins in the vesicle destined fro regulated secretion?

A. The regulated secretion vesicle proteins are bound to lipids for supplying the plasma with new lipids.
B. Proteins in the constitutive secretion vesicle unfold to keep the concentration in the vesicle low, and then refold at the cell surface.
C. none of the above
D. Proteins in the regulated secretion vesicle tend to aggregate and become highly concentrated in the ionic conditions in the vesicle.
E. Proteins in the constitutive secretion vesicle are stored for release in response to a signal.

Answer 46

D. Proteins in the regulated secretion vesicle tend to aggregate and become highly concentrated in the ionic conditions in the vesicle.

Question 47

What process is responsible for organelle turnover in the cell and carries out the regulated destruction of the cell’s own organelles for the purpose of recycling the components of which they are made?

A. phagocytosis
B. now I am self-destructing due to this hard exam.
C. autophagy
D. apoptosis
E. endocytosis

Answer 47

C. autophagy

Question 48

! (EC) Katie has just joined a lab that studies vesicle budding from the Golgi and has been given a cell line that does not form mature vesicles. She wants to start designing some experiments but was not listening carefully when she was told about the molecular defect of this cell line. She is too embarrassed to ask and comes to you for help. She does recall 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?

A. dynamin
B. clathrin
C. Rab
D. adaptin
E. Katie is worried whether the neuroscience material covered in lecture will be heavily covered on the exam.

Answer 48

A. dynamin

Question 49

(EC) A group of BIO329 researchers wanted to sort different white blood cell types (monocytes, lymphocytes, and granulocytes) apart from each other based on size differences and to remove unwanted contaminating red blood cells. After a particular manipulation, the red blood cells lysed. The remaining white blood cells increased in size and, more importantly, the size differences among cells increased, allowing for size-based sorting (which requires minimum size differences among cells). What manipulation did the researchers use to increase cell size?

A. placing cells in an environment with a lower solute concentration than that in the cells
B. placing cells in an environment with lower temperatures than the cells were previously exposed to
C. placing cells in an environment with a higher solute concentration than that in the cells
D. patch-clamp recording to monitor ion channel activity
E. Hey Dae-Sung, the Joly consumer, I hate this kind of long question(- I know, so I put this as an extra !)

Answer 49

A. placing cells in an environment with a lower solute concentration than that in the cells

Question 50

(EC) Autumn is struggling with this question. We can help her, right? So…ouabain is a chemical that inhibits the sodium potassium pump by preventing K+ from binding. What effect would this have on the transportation of sodium in a plant cell and animal cell?

A. It would have no effect on the plant cell, but the animal cell would be inhibited from exporting sodium.
B. It would have no effect on the animal cell, but the plant cell would be inhibited from exporting sodium.
C. it would have no effect on the animal cell, but the plant cell would be inhibited from importing sodium.
D. It would have no effect on the plant cell, but the animal cell would be inhibited from importing sodium.
E. Autumn… this is an interesting question but sorry I cannot help you. Just guess…

Answer 50

A. It would have no effect on the plant cell, but the animal cell would be inhibited from exporting sodium.