DNA and RNA Quiz
Questions: 16 · 10 minutes
1. An enzyme binds near the start of a gene and builds an RNA strand complementary to the DNA template. Which enzyme is it?
DNA ligase
DNA polymerase
RNA polymerase
Aminoacyl-tRNA synthetase
2. After one round of DNA replication, each daughter molecule contains one original strand and one newly synthesized strand. Which replication model does this describe?
Dispersive replication
Conservative replication
Semiconservative replication
Transcriptive replication
3. Which nitrogenous base normally occurs in DNA but not in RNA?
Uracil
Adenine
Cytosine
Thymine
4. A gene's template DNA contains the triplet 3′-TAC-5′. What mRNA sequence is transcribed from it?
5′-UAC-3′
5′-AUG-3′
3′-ATG-5′
5′-TAC-3′
5. A mutation prevents the two parental DNA strands from unwinding at a replication fork. Which enzyme is most directly affected?
DNA ligase
Primase
Helicase
Telomerase
6. Which structural difference commonly distinguishes a DNA nucleotide from an RNA nucleotide?
DNA contains deoxyribose, while RNA contains ribose.
DNA contains phosphate, while RNA does not.
DNA contains a sugar, while RNA contains only bases and phosphate.
DNA nucleotides contain two sugars, while RNA nucleotides contain one.
7. After RNA primers have been removed and replaced with DNA, small breaks remain in the sugar-phosphate backbone between adjacent fragments. Which enzyme seals them?
DNA ligase
Helicase
Primase
RNA polymerase
8. In a eukaryotic cell, where is pre-mRNA from a protein-coding nuclear gene normally synthesized before export?
The nucleus
The cytosol
The Golgi apparatus
The lysosome
9. One DNA strand has the sequence 5′-ATGC-3′. Which sequence correctly represents its complementary, antiparallel strand?
5′-TACG-3′
3′-UACG-5′
3′-ATGC-5′
3′-TACG-5′
10. At a replication fork, one new strand is produced continuously while the other is assembled in short fragments. How are these strands identified?
The template strand is continuous, while the coding strand forms fragments.
The lagging strand is continuous, while the leading strand forms fragments.
Both are leading strands, but only one requires primers.
The leading strand is continuous, while the lagging strand forms Okazaki fragments.
11. A cell has a defective DNA polymerase proofreading function, but replication still proceeds. What outcome is most likely?
RNA primers will never be produced.
More replication errors will remain uncorrected in the new DNA.
The parental DNA strands will remain permanently joined.
Every thymine base will be replaced by uracil.
12. During translation, what is the key role of transfer RNA (tRNA)?
It stores the cell's complete genetic information.
It pairs its anticodon with an mRNA codon and carries the corresponding amino acid.
It joins Okazaki fragments during replication.
It forms the DNA template used by RNA polymerase.
13. A DNA polymerase is extending a new strand. Where can it add the next nucleotide?
To the 5′ phosphate at the beginning of the template strand
To the free 3′ hydroxyl end of the growing strand
To either end of the new strand with equal efficiency
Directly to a nitrogenous base in the middle of the strand
14. In a double-stranded DNA sample, adenine makes up 30% of the bases. What percentage is cytosine?
30%
40%
20%
70%
15. During PCR, a DNA sample is heated so that its two strands separate. Which stage is this?
Denaturation
Annealing
Extension
Ligation
16. A molecule carries a temporary copy of a protein-coding sequence from DNA to a ribosome. Which molecule is it?
Genomic DNA
Ribosomal RNA
Transfer RNA
Messenger RNA