Biol215 unit 2 test

Glycolipids present on red blood cells extend from the ______ face of the plasma membrane. These glycolipids were glycosylated when they were part of the _______ face of the Golgi membrane.

A. luminal;cytoplasmic

B. cytoplasmic;extracellular

C. cytoplasmic;luminal

D. extracellular;luminal

E. extraceullar;cytoplasmic

D

Whith of the following statements regarding anabolio pathways is FALSE?

A. are possible in cells

B. are nonspontaneous

C. are endergonic

D. produce smaller molecules from larger molecules

E. None of the above are false

D

The active site of an enzyme is the region that

A. binds allosteric regulators of the enzyme

B. is involved in the catalytic reaction of an enzyme

C. is inhibited by the presence of a coenzyme or a cofactor

D. binds noncompetitive inhibitors of the enzyme

E. More than one of the above

B

In contrast to the airway of a person afflicted with cystic fibrosis, the airway of a NORMAL individual is ___ relative to the surrounding epithelial cells, which _____ movement of water into the airway.

A. hypotonic;prevents

B. hypotonic;promotes

C. hypertonic;prevents

D. hypertonic;promotes

D

True/False: In the presence of a competitive inhibitor, an enzyme can reach the same Vmax as the inhibited enzyme (i.e. the enzyme alone), but only at higher [S].

True

A mutant cell line contains a defective channel protein that allows potassium ions to easily to pass across the plasma membrane. Increasing the potassium ion permeability will have what effect on the membrane potential (Vm) of cells from this mutant cell line?

A. There will be no change in membrane potential

B. The Vm will become less negative

C. The Vm will become more negative

C

True/False: Cytoskeletal elements can be found in the cytoplasm, the nucleus and the extracellular matrix of eukaryotic cells.

False

During osmosis, there is a net movement of ______ the side of the membrane with higher solute concentration.

A. water to

B. water from

C. solute to

D. solute from

E. both A and D

A

Familial hypercholesterokemia is characterized by which of the following?

A. phagocytosis of LDLs by white blood cells

B. cells that do not synthesize cholesterol

C. abnormally high levels of LDLs in the blood

D. increased uptake of LDLs from the blood

E. more than one of the above

C

True/False: Chemoheterotrophs can convert inorganic carbon into organic molecules

False

True/False: The facilitated diffusion of glucose into cells mediated by the glucome transporter protein requires an input of energy

False

For an enzyme-catalyzed reaction, v actions independtly of [S] when:

A. [S] << Km

B. v = Vmax

C. v = Km

D. [S] = Km

E. both A and B

B

True/False: The hydrocarbon tails of adjacent phospholipid within a lipid layer of a membrane interact through hydrogen bonds

False

Which of the following events is NOT associated with the phagocytosis of a bacterium by a white blood cell (WBC)?

A. Energy for movement of the WBC is converted by mitochondria

B. The membrane of the phagosome is derived from the plasma membrane of the white WBC

C. The enzymes involved in the breakdown of the bacterium were synthesized by the cotranslational import pathway.

D. The phagosome formed will fuse to a lysosome in order to breakdown the bacterium

E. All of the above are involved in this process

E

True/False: The Keq for a particular reversible reaction at equilibrium is 3. This means that, at equilibrium, there are three times more products than reactants

True

Which targeting pathway would a peroxisomal enzyme have gone through in order to carry out its role inside the peroxisome?

A. Cytoplasmic (default)

B. Cotranslational

C. Post translational

D. Could be any of the above, depending on the cell type

E. Not enough information given

C

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True/False: Adding an enzyme to an endergonic reaction can make the reaction exergonic

False

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Which of the following applies ONLY to active transport and NOT facilitated diffusion?

A. requires transporter proteins

B. [S]low --> [S]high

C. energy is not required

D. the concentration gradient provides the necessary energy for movement

E. both A and B

B

True/False: Regarding the sodium-potassium pump, the action of the pump results in more positive charges outside the plasma membrane than inside

True

ATP is considered the energy currency of the cell because:

A. resonance stabilization is increased in the ATP molecule

B. the phosphoanhydride bonds can be hydrolyzed to release usable energy

C. it can transfer heat energy directly to other molecules

D. it is the only cellular molecule capable of storing potential energy

E. more than one of the above is true

B

A freshwater protozoan was placed in solution A and observed to open and close its contractile vacuoles at a rate of 5 contractions per minute. The same protozoan was then placed in solution W and observed to open and close its contractile vacuoles at a rate of 10 contractions per minute. Based on this information, whcih of the following statements is correct?

A. Solutions A and W are both hypertonic relative to the cell

B. Solution W is more hypertonic relative to the cell compared to solution A

C. Solution A is hypertonic relative to solution W

D. Solution A are W are isotonic to each other

E. choices A and B are both correct

C

True/False: During SARS CoV-2 infection, the ACE-2 proteins of the virus binds to a recepton on human cells in order for the virus to enter the cell

False

The transition state of an enzyme catalyzed reaction is

A. higher in energy than that of an uncatalyzed reaction

B. lower in energy than that reaction substrate(s)

C. Considered an intermediate substrate in a metabolic pathway

D. lower in energy than that of an uncatalyzed reaction

E. none of the above

D

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The process by which a vesicle is formed at hte plasma membrane to bring relatively large (0.5> um) substances into the cell is called ____

A. exocytosis

B. endocytosis

C. phagocytosis

D. hemolysis

E. hydrocytosis

C

Which of the following terms describes the net movement of a solte molecule from a region of higher concentration to a region of lower concentration?

A. active transport

B. diffusion

C. osmosis

D. tonicity

E. could be more than one of the above

B

Diphenol oxidase catalyzes the conversion of colorless phenolic compounds into dark colored quinones, which is the mechanism involved in fruit browning. PHBA was found to competitively inhibit the enzyme, while PTU acted as a noncompetitive inhibitor. Based on these findings, which inhibitor would be a better candidate to pursue for an application as a browning retardant of fruit and why?

A. PHBA because it doesn't affect Vmax

B. PHBA because it lowered both Vmax and Km

C. PTU because it does not affect the Km

D. PTU because it lowered Vmax

E. Either PHBA or PTU simce both are inhibitors of the enzyme

D

Lipid X molecules have longer and more saturated hydrocarbon tails compared to molecules of lipid Y. At room temperature, a membrane comprise largely of lipid X will _____ compared to a membrane enriched in lipid Y.

A. be more fluid

B. be less fluid

c. have the same fluidity

B

On a Lineweaver-Burk plot, a compeititve inhibitor will alter the _____ of an enzyme catalyzed reaction.

A. Vmax

B. substrate

C. product

D. Km

E. Km and Vmax

D

the CFTR protien directly transports ____ across the plasma membrane of epithelial cells.

A. Cl- ions

B. Na+ ions

C. water

D. all of the above

E. Cl- and Na+ ions

A

If a reaction is exergonic, this means that the reaction

A. has a positive delta G

B. is not thermodynamically possible

C. releases energy

D. is at equilibrium

E. More than one of the above

C

The concentration of solutes in a red blood cell is about 2%. Red blood cells contain no sucrose or carbamide. Sucrose can not pass through the membrane, but water and carbamide can. Osmosis would cause red blood cells to shirnk the most when immersed in which of the following solutions?

A. hypertonic sucrose solution

B. hypertonic carbamid solution

C. hypotonic sucrose solution

D. pure water

E. could be either A or B

A

Considering how an enzume behaves inside a cell, a low Km indicates that the enzume activity will _____

A. vary with fluctuations in [S]

B. Act at a constant rate regardless of variations in [S]

C. not enough information given

B

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True/False: A solute can be actively transported across a membrane by a channel protein

False

In vitro experiments demonstrate that hexokinase can catalyze a reaction using various hexose sugars as its substrate. Using mannose as a substrate, the Km for the reaction is 0.5 mM. When glucose is the substrate, the Km is 3.0 mM. As indicated by the Km, hexokinase has a ______ affinity for glucose than mannose, suggesting that ___ is the native substrate of hexokinase inside fo a cell.

A. lesser;mannose

B. lesser;glucose

C. greater;glucose

D. greater;mannose

A

In a pulse chase experiment, pancreatic cell

outside the cell

Which of the following reactions could be coupled the reaction below?

XYZ + H2O --> XY + Zi delta G=-6.3 kcal/mol

A. delta G=6 kcal/mol

B. delta G=8 kcal/mol

C. -4 kcal/mol

D. -10 kcal/mol

E. 10 kcal/mol

A

True/False: A hypotonic solution will have a lower solute concentration relative to that inside a cell

True

The lipase enzyme isolated from the yeast Candida rugosa was studied and found to catalyze the reaction shown below. Based on this information, lipase belongs to which class of enzymes?

ethyl acetate + H2O --> acetic acid + ethanol

A. hydrolases

B. isomerases

C. ligases

D. oxireductases

E. transferases

A

Which of the following statements regarding phosphoglycerides and sphingolipids is TRUE?

A. both phosphoglycerides and sphingolipids use glycerol as a backbone molecule

B. only phosphoglycerides have both hydrophobic and hydrophilic regions; sphingolipids are entirely hydrophobic

C. both phosphoglycerides and sphingolipids have two fatty acids attached to their backbone molecule

D. phosphoglycerides are a type of phospholipid; sphingolipids are a type of glycolipid

E. none of the above are true

E

Disassembly and reassembly of the nuclear lamina during cell division is controlled by the phophorylation and dephosphorylation of lamin proteins. When lamins are phosphorylated, the consequent conformation changes weakens the binding between the proteins, causing the structures to fall apart. Dephosphorylation at the end of mitosis causes lamins to reassemble. What types of proteins are involved in the reassembly of lamina?

A. kinases

B. phisphorylases

C. phosphatases

D. none of the above

E. could be either A or B

C

Which of the following is a way that cell membranes of the winter wheat plant are able to maintain proper structure when it is extremely cold?

A. increased amount of unsaturated fatty acids

B. longer fatty acid chains

C. no membrane cholsterol

D. all of the above

E. both A and B

A

During the process of receptor mediated endocytosis, where are the ligand binding domains of the receptor molecules localized after the formation of the endocytic vesicle?

A. facing the inside of the endocytic vesicle

B. facing the outside of the endocytic vesicle

C. the outer surface of the nuceus

D. on the ER

E. facing the inside surface of the cell membrane

A

Select the statement that best describes the mechanism of Na+/glucose cotransporter:

A. glucode moves into the cell with its gradient to drive the transport of Na+ out of the cell against its gradient.

B. Glucose moves with its gradient to drive the transport of Na+ against its gradient. Both Na+ and glucose are moving into the cell

C. Na+ moves into the cell with its gradient to drive the transport of glucose out of the cell against its gradient.

D. Na+ moves with its gradient to drive transport of glucose against its gradient. Both Na+ and glucose are moving into the cell.

E. Na+ moves with is gradient to drive the transport of glucose against is gradient Both Na+ and glucose are moving out of the cell

D

Above the Tm, cholesterol helpe cell membranes maintain proper fluidity by ______

A. decreasing fatty acid tail lengths

B. making membranes less rigid

C. decreasing membrane fluidity

D. making membranes more permeable

E. increasing the number of saturated fatty acids

C

Which type of protein is NOT embedded in the lipid bilayer at all?

A. CFTR

B. glucose transporter

C. integral membrane protein

D. peripheral protein

E. single pass protein

D

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