DNA Structure and Replication: Interactive Learning Quizzes for Medical Students

Question 1

Which of the following accurately describes the structure of the DNA double helix?

Accepted Answer

Antiparallel strands with purine-pyrimidine base pairing

Answer

Parallel strands with purine-purine and pyrimidine-pyrimidine base pairing

Answer

Single-stranded with no specific base pairing rules

Answer

Circular with alternating sugar-phosphate and nitrogenous base backbones

Question 2

Which enzyme is responsible for synthesizing the majority of DNA during replication in eukaryotes?

Accepted Answer

DNA polymerase III

Answer

DNA polymerase I

Answer

DNA polymerase II

Answer

DNA polymerase IV

Question 3

During DNA replication, what are Okazaki fragments?

Accepted Answer

Short, newly synthesized DNA segments on the lagging strand

Answer

Long, continuous DNA strands on the leading strand

Answer

Template strands for DNA synthesis

Answer

Primers for DNA polymerase

Question 4

Which of the following is not a type of DNA repair mechanism?

Accepted Answer

RNA interference

Answer

Nucleotide excision repair

Answer

Base excision repair

Answer

Mismatch repair

Question 5

Which of the following proteins is not directly involved in DNA replication?

Accepted Answer

RNA polymerase

Answer

Helicase

Answer

DNA ligase

Answer

Primase

Question 6

What is the primary function of telomerase in eukaryotic cells?

Accepted Answer

To add telomeric repeats to the ends of chromosomes

Answer

To remove primers from the lagging strand

Answer

To proofread newly synthesized DNA

Answer

To unwind the DNA double helix ahead of the replication fork

Question 7

Which technique has revolutionized the study of DNA structure and sequence?

Accepted Answer

DNA sequencing

Answer

Transmission electron microscopy

Answer

X-ray crystallography

Answer

Magnetic resonance imaging

Question 8

Which chemical bond stabilizes base pairs in the DNA double helix?

Accepted Answer

Hydrogen bond

Answer

Covalent bond

Answer

Ionic bond

Answer

Van der Waals force

Question 9

What type of chemical bond forms between adenine and thymine?

Accepted Answer

Hydrogen bond

Answer

Phosphodiester bond

Answer

Ionic bond

Answer

Van der Waals force

Question 10

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Answer

Polymerase

Answer

Ligase

Answer

Primase

Question 11

What is the role of Okazaki fragments in DNA replication?

Accepted Answer

Short, single-stranded DNA fragments synthesized discontinuously on the lagging strand

Answer

Continuous DNA fragments synthesized on the leading strand

Answer

Primers used to initiate DNA synthesis

Answer

Enzymes that join Okazaki fragments together

Question 12

What is the significance of DNA methylation?

Accepted Answer

It regulates gene expression

Answer

It protects the DNA molecule from degradation

Answer

It aids in DNA repair mechanisms

Answer

It is involved in the process of homologous recombination during meiosis

Question 13

What is the central dogma of molecular biology?

Accepted Answer

DNA → RNA → Protein

Answer

RNA → DNA → Protein

Answer

Protein → DNA → RNA

Answer

Protein → RNA → DNA

Question 14

Which type of RNA molecule carries the genetic code from the nucleus to the ribosome?

Accepted Answer

Messenger RNA (mRNA)

Answer

Transfer RNA (tRNA)

Answer

Ribosomal RNA (rRNA)

Answer

Small nuclear RNA (snRNA)

Question 15

What is the role of telomerase in maintaining genomic stability?

Accepted Answer

It synthesizes new telomeres

Answer

It prevents the shortening of telomeres

Answer

It repairs damaged telomeres

Answer

It regulates the cell cycle

Question 16

How does DNA's unique double helix structure and complementary base pairing ensure accurate genetic information transmission?

Accepted Answer

Facilitates precise base pairing during replication, preserving genetic information.

Answer

Provides multiple copies of genetic information for damage protection.

Answer

Enables efficient strand separation during replication.

Answer

Shields genetic information from environmental damage.

Question 17

Which of the following accurately describes the structure of DNA?

Accepted Answer

A double helix with an alternating pattern of purine and pyrimidine bases

Answer

A single-stranded molecule with a deoxyribose sugar-phosphate backbone

Answer

A double helix with a uniform width throughout its length

Answer

A triple helix with a combination of deoxyribose and ribose sugar-phosphate backbones

Question 18

What is the function of helicase during DNA replication?

Accepted Answer

Separating the two DNA strands at the replication fork.

Answer

Synthesizing new DNA strands.

Answer

Proofreading the newly synthesized DNA strands.

Answer

Joining the Okazaki fragments on the lagging strand.

Question 19

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

Accepted Answer

Ribose sugar

Answer

Deoxyribose sugar

Answer

Phosphate group

Answer

Adenine

Question 20

Which enzyme is responsible for adding nucleotides to the growing DNA strand during replication?

Accepted Answer

DNA polymerase

Answer

Helicase

Answer

Primase

Answer

Ligase

Question 21

What is the role of telomerase in DNA replication?

Accepted Answer

Preventing the loss of genetic information at the ends of chromosomes.

Answer

Initiating DNA replication at multiple origins.

Answer

Synthesizing Okazaki fragments on the lagging strand.

Answer

Proofreading newly synthesized DNA strands.

Question 22

During DNA replication, which polymerase specifically synthesizes the new DNA strand on the leading strand?

Accepted Answer

DNA polymerase III

Answer

DNA polymerase I

Answer

DNA polymerase II

Answer

DNA polymerase IV

Question 23

How does DNA replication ensure the continuity of genetic information during cell division?

Accepted Answer

It creates identical copies of the genetic information.

Answer

It prevents mutations in the genetic material.

Answer

It promotes genetic diversity in offspring.

Answer

It repairs damaged regions in the DNA sequence.

Question 24

Which nitrogenous base is complementary to adenine in DNA?

Accepted Answer

Thymine

Answer

Guanine

Answer

Cytosine

Answer

Uracil

Question 25

What is the name of the enzyme responsible for unwinding the DNA double helix ahead of the replication fork?

Accepted Answer

Helicase

Answer

Polymerase

Answer

Primase

Answer

Ligase

Question 26

What is the role of topoisomerase in DNA replication?

Accepted Answer

To relax the DNA double helix ahead of the replication fork

Answer

To proofread newly synthesized DNA strands

Answer

To join Okazaki fragments on the lagging strand

Answer

To remove RNA primers from the ends of DNA fragments

Question 27

Which of the following base pairs is not present in the conventional DNA structure?

Accepted Answer

Uracil-Guanine

Answer

Adenine-Thymine

Answer

Guanine-Cytosine

Answer

Cytosine-Guanine

Question 28

The three-dimensional configuration of DNA is primarily maintained by:

Accepted Answer

Hydrogen bonds

Answer

Covalent bonds

Answer

Ionic bonds

Answer

Van der Waals interactions

Question 29

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

DNA helicase

Answer

DNA polymerase

Answer

DNA ligase

Answer

RNA polymerase

Question 30

The process of DNA replication is:

Accepted Answer

Semi-conservative

Answer

Conservative

Answer

Dispersive

Answer

Non-enzymatic

Question 31

Which protein is involved in proofreading and error correction during DNA replication?

Accepted Answer

Exonuclease

Answer

DNA polymerase

Answer

Helicase

Answer

Ligase

Question 32

In eukaryotic cells, the replication origin is characterized by a specific DNA sequence called:

Accepted Answer

ARS

Answer

Promoter

Answer

Enhancer

Answer

Kozak

Question 33

A key difference between DNA and RNA is their:

Accepted Answer

Sugar backbone

Answer

Nitrogenous bases

Answer

Double-stranded structure

Answer

Function

Question 34

According to the central dogma of molecular biology, the flow of genetic information is:

Accepted Answer

DNA -> RNA -> Protein

Answer

Protein -> RNA -> DNA

Answer

RNA -> DNA -> Protein

Answer

DNA -> Protein -> RNA

Question 35

Which of the following accurately describes the structure of DNA?

Accepted Answer

Double helix with antiparallel strands

Answer

Single helix with antiparallel strands

Answer

Single helix with parallel strands

Answer

Double helix with parallel strands

Question 36

What is the complementary base pairing rule for DNA?

Accepted Answer

A pairs with T and C pairs with G

Answer

A pairs with G and C pairs with T

Answer

A pairs with C and T pairs with G

Answer

A pairs with U and C pairs with G

Question 37

Which enzyme is primarily responsible for catalyzing the polymerization of nucleotides during DNA replication?

Accepted Answer

DNA polymerase

Answer

Helicase

Answer

Topoisomerase

Answer

RNA polymerase

Question 38

What is the role of the lagging strand during DNA replication?

Accepted Answer

Synthesized discontinuously in the 5' to 3' direction

Answer

Synthesized continuously in the 5' to 3' direction

Answer

Synthesized continuously in the 3' to 5' direction

Answer

Synthesized discontinuously in the 3' to 5' direction

Question 39

Which of the following techniques commonly amplifies specific DNA sequences?

Accepted Answer

Polymerase chain reaction (PCR)

Answer

Gel electrophoresis

Answer

Restriction enzyme digestion

Answer

Southern blotting

Question 40

Which of the following is NOT a potential application of DNA replication technology?

Accepted Answer

Quantum computing

Answer

Diagnostics

Answer

Forensics

Answer

Genetic engineering

Question 41

How does the structure of nucleotides contribute to the stability of the DNA double helix?

Accepted Answer

The hydrophobic stacking interactions between adjacent nucleotides stabilize the double helix.

Answer

The sugar-phosphate backbone forms weak hydrogen bonds with the nitrogenous bases.

Answer

The hydrogen bonds between complementary nitrogenous bases are stronger than the covalent bonds between nucleotides.

Answer

The double helix is stabilized by strong electrostatic interactions between the negatively charged phosphate groups and the positively charged nitrogenous bases.

Question 42

How does the origin of replication contribute to the coordination of DNA replication throughout the genome?

Accepted Answer

Initiates replication at specific genomic locations, ensuring complete genome replication.

Answer

Provides the template for DNA polymerases to synthesize new DNA strands.

Answer

Prevents replication of damaged DNA.

Answer

Facilitates DNA packaging into chromatin.

Question 43

Which of the following correctly pairs the pyrimidine bases with their complementary purine bases in DNA?

Accepted Answer

Thymine: Adenine, Cytosine: Guanine

Answer

Thymine: Guanine, Cytosine: Adenine

Answer

Adenine: Thymine, Guanine: Cytosine

Question 44

What is the three-dimensional structure of a DNA molecule?

Accepted Answer

Double helix

Answer

Single helix

Answer

Circular

Answer

Triple helix

Question 45

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Answer

Topoisomerase

Answer

Ligase

Answer

DNA Polymerase

Question 46

During DNA replication, what is the primary function of DNA polymerase?

Accepted Answer

Synthesizes new DNA strands complementary to the template strands

Answer

Unwinds the DNA helix

Answer

Proofreads newly synthesized DNA strands for errors

Question 47

What are Okazaki fragments?

Accepted Answer

Short DNA segments synthesized on the lagging strand during DNA replication

Answer

Segments of DNA joined together by DNA ligase

Answer

Regions of DNA where replication initiates

Question 48

Which characteristic is NOT a property of the genetic code?

Accepted Answer

Overlapping

Answer

Unambiguous

Answer

Triplet

Answer

Degenerate

Question 49

What is the role of primers in DNA replication?

Accepted Answer

Provide a free 3'-OH group for DNA polymerase to initiate DNA synthesis

Answer

Protect the ends of DNA strands from degradation

Answer

Initiate the unwinding of the DNA helix

Question 50

Which type of mutation results in the replacement of one amino acid with another in a protein?

Accepted Answer

Missense mutation

Answer

Frameshift mutation

Answer

Silent mutation

Answer

Nonsense mutation

Question 51

What is the primary function of telomerase in DNA replication?

Accepted Answer

Maintains the length of telomeres at the ends of chromosomes

Answer

Initiates DNA replication at specific sites

Answer

Proofreads newly synthesized DNA strands