Q: Which of the following best describes the flow of genetic information in a eukaryotic cell?

$$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$$

Question 1

Which of the following statements best explains why DNA replication is described as 'semiconservative'?

Accepted Answer

Each new DNA molecule consists of one old (parental) strand and one new strand.

Question 2

A scientist discovers a segment of DNA with 30% adenine. According to Chargaff’s rules, what percentage of guanine would you expect to find in this DNA?

Accepted Answer

$$20\%$$

Question 3

During DNA replication, which enzyme is responsible for 'unzipping' the DNA double helix by breaking hydrogen bonds between base pairs?

Accepted Answer

Helicase

Question 4

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 in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in short fragments.

Question 5

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA}. $$What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 6

Which of the following best explains why a frameshift mutation is often more damaging than a base pair substitution?

Accepted Answer

Frameshift mutations alter the reading frame, changing every amino acid downstream of the mutation.

Question 7

In eukaryotic cells, what is the primary function of histone proteins in chromatin structure?

Accepted Answer

They package and organize DNA into nucleosomes, aiding in DNA compaction and gene regulation.

Question 8

Which of the following modifications occurs to pre-mRNA before it leaves the nucleus in eukaryotic cells?

Accepted Answer

Addition of a 5' cap and a poly-A tail, and removal of introns

Question 9

A patient is exposed to high levels of UV radiation, which causes thymine dimers in their DNA. What is the most likely consequence if these mutations are not repaired?

Accepted Answer

The patient may develop skin cancer due to carcinogenic mutations.

Question 10

During translation, what is the role of the anticodon found on tRNA molecules?

Accepted Answer

It pairs with the complementary codon on mRNA to ensure correct amino acid placement.

Question 11

Which of the following best describes the flow of genetic information in a eukaryotic cell?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 12

A gene mutation changes the DNA sequence from $$	ext{GAA} to$$ $$	ext{GAG}$$, but both codons code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 13

Which of the following is true regarding the structure of RNA compared to DNA?

Accepted Answer

RNA is single-stranded and contains uracil instead of thymine.

Question 14

Which of the following best explains why multiple codons can code for the same amino acid?

Accepted Answer

The genetic code is redundant, allowing for silent mutations.

Question 15

A scientist is studying a eukaryotic gene and finds that the initial RNA transcript is much longer than the final mRNA. What process accounts for this difference?

Accepted Answer

Splicing out introns during RNA processing

Question 16

Which of the following scenarios would most likely result in a frameshift mutation?

Accepted Answer

A single base pair is deleted from the coding sequence.

Question 17

During translation, which site on the ribosome holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 18

Which of the following best describes the function of DNA ligase during DNA replication?

Accepted Answer

It joins Okazaki fragments on the lagging strand.

Question 19

A mutation rate in a eukaryotic gene is $$1/100,000$$ per generation. If an organism has 20,000 genes, how many new mutations would you expect per generation?

Accepted Answer

$$0.2$$ 	imes 20,000 = 200$

Question 20

Which of the following is a real-life example of a missense mutation?

Accepted Answer

A mutation that changes one amino acid in hemoglobin, leading to sickle cell anemia.

DNA Structure, Replication, and Protein Synthesis

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