MT 2

Which of the following statements are true regarding individuals with type AB blood?

- AB individuals are universal plasma donors. - AB individuals are universal recipients of red blood cells.

Structural Features of N-linked Glycans

- Linked to protein at asparagine side chain - 5-sugar core group is GlcNAc2Man3. - First monosaccharide is usually GlcNAc.

Structural Features of O-linked Glycans

- Linked to protein at serine or threonine hydroxyl - First monosaccharide is usually GalNAc. - Core group is variable.

What characteristic(s) of the structure confirm it as an N-linked glycan rather than an O-linked glycan?

- The oligosaccharide is linked to the glycoprotein by a glycosidic bond with an asparagine residue. - The monosaccharide linked directly to the amino acid is N-acetylglucosamine. - The structure contains a core group composed of N-acetylglucosamine and mannose in a specific arrangement characteristic of N-linked glycans.

The sodium-potassium ATPase hydrolyzes ATP to pump two K+ ions inside the cell and three Na+ ions out. This is an example of energy conversion in which the energy from ATP is converted to

- an electrical potential across the cell membrane. - a chemical gradient across the cell membrane.

The flux of which of the following reactions would depend only on substrate availability?

- glucose-6-phosphate → fructose-6-phosphate - dihydroxyacetonephosphate → glyceraldehyde-3-phosphate

Which of the following are functions of proteoglycans?

- sequestering cytokines - facilitating cell migration - regulating the permeability of some membranes

Which of the following reactions from glycolysis is an example of substrate-level phosphorylation?

1,3-Bisphosphoglycerate + ADP → 3-Phosphoglycerate + ATP

descriptions of these chemical reactions in the order that they occur in stage I of glycolysis (from beginning to end).

1. Phosphoryl transfer from ATP to aldose 2. Isomerzation of aldose to ketose 3. Phosphoryl transfer from ATP to ketose 4. Reverse of idol condensation 5. Isomerzation of ketose to aldose

How many enzymes catalyze irreversible reactions in stage I of glycolysis under cellular conditions?

2

What is the net reaction for stage I of glycolysis if the pathway begins with 2 moles of glucose?

2 Glucose + 4 ATP → 4 Glyceraldehyde-3-phosphate + 4 ADP

If 2 moles of glucose were converted into 4 moles of pyruvate through the glycolytic pathway, there would be a net yield of

4 ATP; Stage I of glycolysis requires the investment of 2 ATP for every mole of glucose, while stage II produces 4 ATP for every mole of glucose.

At normal blood glucose concentrations (5 mM), hexokinase has a reaction rate that is about ______ than that of glucokinase.

4x higher

A net yield of __ ATP would be produced from the conversion of three molecules of glucose into pyruvate.

6

Individuals with Type AB blood can donate red blood cells to which individuals?

AB

High EC of Cell

ATP bound to effector site [ADP]/[ATP] <1 Affinity for F6P decreased Predominant form is T-state

Kinases most commonly use which substrate as a source of phosphate for phosphoryl transfer reactions?

ATP-Mg2+

An individual with type A blood donates whole blood. After the donation, the red cells are separated from the plasma before the blood products are used. How does this step affect the number of recipients who can receive blood products from this individual?

After separation, the red cells can be donated to recipients of two different blood types and the plasma can be used with individuals of three different blood types.

Which of the following would be an example of decreasing entropy?

An anabolic pathway

Which of the following statements is correct?

An exergonic reaction drives an endergonic reaction in living systems.

Blood Type B

Anti-A in plasma B antigen on RBC

Blood Type A

Anti-B in plasma A antigen on RBC

for the reaction A to B, the Keq is 104. If a reaction mixture originally contains 1 mmol of A and no B, which one of the following must be true?

At equilibrium, there will be far more B than A

Blood Type O

Both anti-A and anti-B in plasma No antigens on RBC

Individuals with type AB blood express

Both α-1,3-galactosyltransferase and α-1,3-N-acetylgalactosaminyltransferase

Which statement best describes the relationship between anabolic and catabolic pathways?

Catabolic pathways convert energy-rich compounds into energy-depleted compounds and are generally associated with breakdown, whereas anabolic pathways use compounds high in chemical energy for biosynthesis.

Which of the following is NOT an outcome of glycolysis?

Generation of 1 Pyruvate

Which of the following reactions in glycolysis requires ATP as a substrate?

Hexokinase

Which of the following statements best describes the effect of ADP on the activity of PFK-1?

High concentrations of ADP block the inhibitory effect of ATP by competing for the same allosteric site on PFK-1.

Which of the following statements is FALSE regarding glycan structure determination?

Identical classes of glycoconjugates have the same structure.

In which situation is glycolysis alone likely to be a major contributor to ATP generation?

In erythrocytes

Why is penicillin considered a suicide inhibitor?

It forms an irreversible covalent bond with its enzyme target.

Which of the following is NOT correct for phosphoenolpyruvate?

It is stable in cells.

For the reaction: A + B ↔ C + D, which of the following is correct?

Keq = [C][D]/[A][B]

What method(s) could be used to determine the structure and composition of each glycan group?

Mass spectrometry can be used to determine that there are three different glycan groups based on their different masses. The three different glycans could then be isolated and the purified samples could each be treated with a series of sugar-specific glycosylases. The resulting cleavage products can be analyzed by liquid chromatography to determine the arrangement of sugars. Mass spectrometry can again be used to confirm this identity by determining the mass of the cleavage products.

Under anaerobic conditions, pyruvate is metabolized to either ethanol or lactate to provide which important coenzyme?

NAD+

Blood Type AB

No anti-A or anti-B in plasma Both A and B antigens on RBC

Phosphorylation of glucose requires 1 ATP. Can the reverse reaction be used for substrate-level phosphorylation?

No, phosphate hydrolysis of glucose-6-phosphate is not spontaneous enough to couple to ATP synthesis.

Would penicillin be expected to have an equal ability to kill both Gram-positive and Gram-negative bacteria? Why or why not?

No; the lipopolysaccharide layer surrounding Gram-negative bacteria can inhibit penicillin uptake by these bacteria.

Individuals with Type O blood can donate plasma to which individuals?

O

Which enzyme's activity is controlled by the levels of glucose-6-P and fructose-6-P in the cell?

Phosphoglucoisomerase

Which of the following reactions in glycolysis is an aldose to ketose isomerization?

Phosphohexose isomerase/phosphoglucose isomerase

Which of the following is correct concerning the first law of thermodynamics in biological systems?

Pressure and volume do not change.

Which of the following fates of pyruvate is correct?

Pyruvate enters the citrate cycle under aerobic conditions.

Consider two reactions. Reaction 1 (P → Q) has ΔG = 2.3 kJ/mol. Reaction 2 (Q → R) has ΔG = 12.3 kJ/mol. Which reaction is more likely to require coupling to ATP or the equivalent in order to be spontaneous under cellular conditions?

Reaction 2 (Q → R). This reaction is nonspontaneous and operates far from equilibrium in the cell. It will not be able to proceed as written in the cell without coupling to a process with a large negative free energy change (such as ATP hydrolysis).

Which of the following is least likely to affect the metabolic flux of a metabolic pathway?

Steady-state substrate concentrations

Which of the following reactions in glycolysis is a ketose to aldose isomerization?

Triose phosphate isomerase

The number of structurally different polysaccharides that can be made with 20 different monosaccharides is far greater than the number of different polypeptides that can be made with 20 different amino acids if both polymers contain an equal number of total residues.

True

In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard free-energy change (ΔG'°) of 23.8 kJ/mol. Under what conditions (encountered in a normal cell) will the free-energy change (deltaG) be negative, enabling the reaction to proceed to the right?

When there is a high concentration of fructose 1,6-bisphosphate relative to the concertation of products

Which statement explains why glucose phosphorylation could not occur without ATP investment?

Without ATP investment, one or both of the substrates would need to exceed the solvent capacity of the cell for glucose phosphorylation to occur.

Low EC of Cell

[ADP]/[ATP] >1 ADP bound to effector site Predominant form is R-state Affinity for F6P increased

In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues:

asparagine, serine, or threonine

The reaction A + B to C has a deltaG° of -20 kJ/mol at 25° C. Starting under standard conditions, one can predict that:

at equilibrium, the concentration of C will be much greater than the concentration of A or B

Gram-negative bacteria cell walls

contain a periplasm separating the outer and inner membrane.

Gram-positive bacteria cell walls

contain lipoteichoic acid on the cell membrane surface.

The first reaction in glycolysis that results in the formation of an energy-rich compound is catalyzed by

glyceraldehyde-3-phosphate dehydrogenase

The surface glycan antigens from a variety of microbes can be immobilized on an array. These arrays can then incubated with antibodies isolated from a variety of animals. What type of information could be determined from this experiment?

identification of microbes that have caused an immune response in each animal

Which of the following differentiates the biochemical standard state from the standard state when discussing standard free energy changes?

pH of 7

A(n) __________ inhibitor for transpeptidase is penicillin.

suicide

Based on the free energy change, which of the following steps in glycolysis would be considered irreversible under cellular conditions?

the conversion of Fructose-6-phosphate to Fructose-1,6-bisphosphate requires ATP and has a large free energy change

A hydrophobic environment is necessary for optimal activity of phosphoglycerate kinase

to prevent hydrolysis of 1,3-bisphosphoglycerate.

Which bacterial enzyme is inhibited by penicillin?

transpeptidase

Glucokinase is important for the regulation of glycolysis because it

traps extra glucose in liver cells for glycogen production.

Of the three thermodynamic quantities, ΔG, ΔH, ΔS, which is most useful for determining spontaneity of a reaction?

ΔG

At standard conditions, the equilibrium lies toward products for a given biochemical reaction. What is known about the change in free energy?

ΔG°is less than 0.

In which case will a reaction be spontaneous only above a certain temperature according to the Gibbs free energy equation?

ΔH > 0; ΔS > 0

For ATP, cleavage of the bond between __________ has the largest ΔG°′

α phosphate and β phosphate

Individuals with type A blood express ___

α-1,3-N-acetylgalactosaminyltransferase

Individuals with type B blood express __

α-1,3-galactosyltransferase

One method of generating a universal blood supply is to use enzymes to modify the glycan structure of the blood group antigens. Which of the following enzymes could be used to convert type B blood to type O?

α-galactosidase