Q: Which of the following is a correct formula for the calculation of the free energy change ($$\Delta G) $$for the inward transport of an uncharged solute across a membrane?

$$\Delta G = RT \ln \left( \frac{[S]_{\text{outside}}}{[S]_{\text{inside}}} \right)$$

Question 1

Which of the following statements best describes the relationship between the structure and function of biological macromolecules?

Accepted Answer

The order and bonding of monomers form the basis for the three-dimensional structure and therefore function of the polymer.

Question 2

Which amino acid is unique among the non-polar amino acids in that it does not have separate L and D isomers?

Accepted Answer

Glycine

Question 3

A peptide bond is formed between two amino acids by which type of reaction?

Accepted Answer

Dehydration (condensation)

Question 4

Which of the following best distinguishes a polypeptide from a protein?

Accepted Answer

A protein implies function, while a polypeptide is a structural term.

Question 5

Which of the following amino acids is referred to as the 'helix breaker' in protein secondary structure, and why?

Accepted Answer

Proline, because it lacks the hydrogen atom needed for hydrogen bonding.

Question 6

Hemoglobin is an example of a protein with which level of structural organization?

Accepted Answer

Quaternary structure

Question 7

Which component of DNA and RNA is responsible for the 'acidic' part of nucleic acid?

Accepted Answer

The phosphate group

Question 8

Which of the following best describes the directionality of nucleic acid polymers?

Accepted Answer

Nucleic acid sequences are conventionally written in the 5ʹ to 3ʹ direction.

Question 9

Which of the following is a correct formula for the calculation of the free energy change ($$\Delta G) $$for the inward transport of an uncharged solute across a membrane?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[S]_{	ext{outside}}}{[S]_{	ext{inside}}} ight)$$

Question 10

A plant cell must maintain internal pressure (turgor pressure) to force its plasma membrane against the cell wall. To do so, the interior of the cell must be _________ to its environment.

Accepted Answer

Hypertonic

Question 11

Which of the following best explains why transverse diffusion (flip-flop) of lipids is more frequent in living biological membranes than in artificial bilayers?

Accepted Answer

Cells contain a protein (flippase) that catalyzes the transverse diffusion of lipids.

Question 12

Which of the following is true regarding the E2 conformation (open to the outside of the cell) of the Na+/K+ pump?

Accepted Answer

It binds K+ strongly and Na+ weakly.

Question 13

Which of the following best describes the effect of membrane potential ($$V_m) on $$the free energy change ($$\Delta G) $$for the import of calcium ions ($$	ext{Ca}^{2+}) $$into a typical cell?

Accepted Answer

It would make $$\Delta G$$ more negative.

Question 14

Which of the following best explains why the graph of the rate of facilitated diffusion versus substrate concentration is not linear like the graph of simple diffusion versus substrate concentration?

Accepted Answer

In facilitated diffusion there is a limited amount of active protein, so at higher substrate concentrations, the protein becomes saturated.

Question 15

Which of the following classes of enzymes would catalyze the reaction: $$A - PO_4$ + B \rightarrow A + B - PO_4$?

Accepted Answer

Transferases

Question 16

Which of the following statements about enzyme inhibition is correct?

Accepted Answer

Competitive inhibitors bind to the active site and compete with the substrate.

Question 17

Which of the following best describes the role of allosteric regulation in enzyme activity?

Accepted Answer

Allosteric regulation involves a change in the shape of the enzyme or enzyme complex, affecting its activity.

Question 18

Which of the following is a major function of glycolipids in the plasma membrane?

Accepted Answer

Specialized membrane components, often involved in cell recognition and signaling

Chemical Components of Cells: Amino Acids, Nucleic Acids, Sugars, and Lipids

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