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

Question 1

Which of the following best describes the difference between a DNA nucleotide and an RNA nucleotide, as shown in the diagrams?

Accepted Answer

DNA nucleotides contain the sugar deoxyribose and the base thymine, while RNA nucleotides contain ribose and the base uracil.

Question 2

What is the primary function of DNA polymerase during DNA replication?

Accepted Answer

To add free nucleotides to the 3' end of a growing DNA strand and proofread for errors.

Question 3

Why is DNA replication described as 'semiconservative'?

Accepted Answer

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

Question 4

Which of the following best explains the need for DNA packaging in eukaryotic cells?

Accepted Answer

To fit the large amount of DNA into the small space of the nucleus and facilitate chromosome segregation during cell division.

Question 5

What is the role of histones in the organization of eukaryotic DNA?

Accepted Answer

They form nucleosomes by associating with DNA, aiding in DNA packaging and gene regulation.

Question 6

According to the central dogma of molecular biology, what is the correct flow of genetic information?

Accepted Answer

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

Question 7

Which of the following statements about promoters is correct?

Accepted Answer

Promoters are binding sites for RNA polymerase, ensuring transcription starts at the correct location.

Question 8

What is the function of the anticodon region of tRNA during translation?

Accepted Answer

It pairs with the complementary codon on mRNA, ensuring the correct amino acid is added to the polypeptide chain.

Question 9

Which property of the genetic code allows for the production of human insulin in bacteria?

Accepted Answer

The genetic code is nearly universal, allowing genes from one species to be expressed in another.

Question 10

What is the effect of a nonsense mutation on a protein-coding gene?

Accepted Answer

It introduces a premature stop codon, leading to a truncated, likely nonfunctional protein.

Question 11

Which of the following best describes the function of the lac operon repressor protein in E. coli?

Accepted Answer

It binds to the operator to block transcription when lactose is absent.

Question 12

What is the main purpose of RNA splicing in eukaryotic cells?

Accepted Answer

To remove introns and join exons, producing a mature mRNA for translation.

Question 13

Which modification is added to the 5' end of eukaryotic mRNA, and what is its function?

Accepted Answer

A 5' cap; it facilitates mRNA export, protects from degradation, and assists ribosome binding.

Question 14

Which of the following is a characteristic of cancer cells?

Accepted Answer

They exhibit abnormal, disorganized growth and lack contact inhibition.

Question 15

What is the difference between proto-oncogenes and oncogenes?

Accepted Answer

Proto-oncogenes are normal genes that promote cell division; when mutated, they become oncogenes that cause uncontrolled cell division.

Question 16

Which enzyme is used in genetic engineering to cut DNA at specific sequences?

Accepted Answer

Restriction enzyme (endonuclease)

Question 17

What is the main purpose of the polymerase chain reaction (PCR) in molecular biology?

Accepted Answer

To amplify specific DNA sequences, generating billions of copies from a small sample.

Question 18

Which of the following best describes a transgenic organism?

Accepted Answer

An organism that has acquired genes from another species through artificial means.

Question 19

What is the function of ribosomal RNA (rRNA) during translation?

Accepted Answer

It forms the core structure of the ribosome and catalyzes peptide bond formation.

Question 20

Which of the following is a possible consequence of a frameshift mutation?

Accepted Answer

The reading frame is altered, resulting in a completely different and usually nonfunctional protein.

Molecular Biology: DNA Structure, Gene Expression, and Genetic Engineering

Study Guide - Practice Questions