Question 1

Which of the following best explains why the peptide bond in proteins is neither a true single nor a true double bond?

Accepted Answer

Because the peptide bond has a conjugated system, allowing for resonance between the carbonyl and amide nitrogen.

Question 2

Which of the following statements about prokaryotic and eukaryotic cells is correct?

Accepted Answer

Eukaryotic cells have a membrane-bound nucleus, while prokaryotic cells do not.

Question 3

A buffer is prepared using acetic acid and sodium acetate. If the pH of the buffer is equal to the pKa of acetic acid, what is the ratio of acetate ion to acetic acid?

Accepted Answer

$$1:1$$

Question 4

Which of the following best describes the hydrophobic effect in protein folding?

Accepted Answer

It is the tendency of nonpolar amino acids to avoid water and aggregate in the protein interior.

Question 5

Which of the following is NOT a component of a nucleotide?

Accepted Answer

A carboxyl group

Question 6

A solution contains $$0.1 M $$acetic acid ($$pK_a = 4.76) $$and $$0.1 M $$sodium acetate. What is the pH of the solution after adding $$0.01$$ mol of HCl to $$1 L of $$this buffer?

Accepted Answer

$$4.66$$

Question 7

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 8

Which of the following amino acids is most likely to be found in the interior of a globular protein?

Accepted Answer

Valine

Question 9

During translation, which type of RNA carries the amino acid to the ribosome?

Accepted Answer

tRNA

Question 10

Which of the following best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water is highly polar and can stabilize ions through hydration shells.

Question 11

A protein is found to have a high proportion of proline residues. Which level of protein structure is most likely to be affected?

Accepted Answer

Secondary structure

Question 12

Which of the following best describes the role of buffers in biological systems?

Accepted Answer

Buffers maintain a constant pH by neutralizing added acids or bases.

Question 13

Which of the following is a correct statement about the central dogma of molecular biology?

Accepted Answer

Information flows from DNA to RNA to protein.

Question 14

Which of the following best describes the tertiary structure of a protein?

Accepted Answer

The overall three-dimensional folding of a single polypeptide chain.

Question 15

A DNA sample is found to have 30% adenine. What is the percentage of guanine in the sample?

Accepted Answer

20%

Question 16

Which of the following amino acids is most likely to be phosphorylated during cell signaling?

Accepted Answer

Serine

Question 17

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The association of multiple polypeptide chains into a functional protein complex.

Question 18

Which of the following best explains why the pH of a buffer solution changes only slightly upon addition of a small amount of acid or base?

Accepted Answer

The buffer contains a weak acid and its conjugate base, which neutralize added acid or base.

Question 19

Which of the following is a correct statement about the hydrogen bonding in water?

Accepted Answer

Each water molecule can form up to four hydrogen bonds.

Question 20

Which of the following best describes the difference between a nucleoside and a nucleotide?

Accepted Answer

A nucleotide contains a phosphate group, while a nucleoside does not.

Biochemistry Study Guide: Cell Structure, Water, pH, Nucleic Acids, and Proteins

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