Question 1

Which of the following best describes the Central Dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

A scientist isolates a nucleic acid and determines that it contains the bases adenine, guanine, cytosine, and thymine, as well as deoxyribose sugar. Which type of molecule has the scientist most likely isolated?

Accepted Answer

DNA

Question 3

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The two strands are held together by hydrogen bonds between complementary bases.

Question 4

If one strand of a DNA molecule has the sequence 5'-ATCGGTA-3', what is the sequence of the complementary strand?

Accepted Answer

3'-TAGCCAT-5'

Question 5

Why are the ends of a DNA strand labeled 5’ and 3’?

Accepted Answer

They refer to the carbon atoms in the deoxyribose sugar to which the phosphate group is attached.

Question 6

Which of the following correctly pairs a purine with a pyrimidine in DNA?

Accepted Answer

Adenine with thymine

Question 7

During DNA replication, which enzyme is responsible for unwinding the double helix?

Accepted Answer

Helicase

Question 8

What is the role of single-strand binding proteins during DNA replication?

Accepted Answer

They prevent the separated DNA strands from re-annealing.

Question 9

Which enzyme synthesizes short RNA primers during DNA replication?

Accepted Answer

Primase

Question 10

Why is DNA replication described as 'semi-conservative'?

Accepted Answer

Each new DNA molecule consists of one parental and one newly synthesized strand.

Question 11

Which of the following best describes the difference between the leading and lagging strands during DNA replication?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments.

Question 12

Okazaki fragments are:

Accepted Answer

Short segments of DNA synthesized on the lagging strand.

Question 13

Which enzyme is responsible for joining Okazaki fragments together during DNA replication?

Accepted Answer

DNA ligase

Question 14

A mutation occurs that disables DNA polymerase’s proofreading function. What is the most likely consequence?

Accepted Answer

The error rate during DNA replication will increase.

Question 15

A patient is exposed to a chemical that breaks hydrogen bonds in DNA. Which of the following is the most immediate effect on the DNA molecule?

Accepted Answer

The DNA double helix will unwind and separate into single strands.

Question 16

Which of the following sequences is complementary to the DNA strand 3'-GGCATTA-5'?

Accepted Answer

5'-CCGTAAT-3'

Question 17

Which of the following best explains why DNA polymerase can only add nucleotides to the 3’ end of a growing DNA strand?

Accepted Answer

The 3’ end has a free hydroxyl group that forms a bond with the incoming nucleotide’s phosphate group.

Question 18

During DNA replication, which of the following is the correct order of enzyme activity?

Accepted Answer

Helicase → Primase → DNA polymerase → DNA ligase

Question 19

A researcher is studying a new organism and finds that its DNA contains 30% adenine. According to Chargaff’s rules, what percentage of the DNA bases should be guanine?

Accepted Answer

$$20\%$$

Question 20

Which of the following best describes the role of primers in DNA replication?

Accepted Answer

They provide a starting point with a free 3’ hydroxyl group for DNA polymerase to begin synthesis.

DNA: The Molecular Basis of Inheritance – Structure, Function, and Replication

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