Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

Genetic information flows from DNA to RNA to protein.

Question 2

What is the chemical bond that links nucleotides together in a nucleic acid chain?

Accepted Answer

Phosphodiester bond

Question 3

Which nitrogenous bases are classified as purines?

Accepted Answer

Adenine and Guanine

Question 4

In the structure of DNA, which base pairs are connected by three hydrogen bonds?

Accepted Answer

Guanine and Cytosine

Question 5

What is the main difference between ribose and deoxyribose sugars in nucleic acids?

Accepted Answer

Ribose has a hydroxyl group at carbon 2, deoxyribose has a hydrogen.

Question 6

A human somatic cell contains how many chromosomes?

Accepted Answer

46

Question 7

Which histone protein is responsible for linking adjacent nucleosomes and forming the 30 nm solenoid structure?

Accepted Answer

H1

Question 8

During transcription, in which direction does RNA polymerase synthesize the new RNA strand?

Accepted Answer

5' to 3'

Question 9

Which of the following modifications occurs at the 5' end of eukaryotic mRNA before it leaves the nucleus?

Accepted Answer

Addition of a 7-methylguanosine cap

Question 10

Alternative splicing of mRNA allows for:

Accepted Answer

The production of multiple protein isoforms from a single gene.

Question 11

Which sequence is commonly found in the promoter region of eukaryotic genes and is crucial for transcription initiation?

Accepted Answer

TATA box

Question 12

What is the function of CpG island methylation in gene regulation?

Accepted Answer

It blocks transcription factor binding, leading to gene silencing.

Question 13

Which post-translational modification of histones is most commonly associated with increased gene expression?

Accepted Answer

Acetylation of lysines

Question 14

A mutation in the splice donor site of a gene would most likely result in:

Accepted Answer

Failure to remove introns from the pre-mRNA.

Question 15

Which of the following is NOT a function of the 5' cap on eukaryotic mRNA?

Accepted Answer

Promotes splicing of introns

Question 16

If a gene is heavily methylated at its promoter region, what is the expected effect on its expression?

Accepted Answer

Expression will decrease due to blocked transcription initiation.

Question 17

Which equation correctly represents the formation of a phosphodiester bond between two nucleotides?

Accepted Answer

$$\mathrm{Nucleotide}_1 + \mathrm{Nucleotide}_2 \rightarrow \mathrm{Nucleotide}_1{-}O{-}P{-}O{-}\mathrm{Nucleotide}_2 + H_2O$$

Question 18

Which of the following statements about the human genome is correct?

Accepted Answer

The nuclear genome contains approximately 3 billion base pairs.

Question 19

Which type of RNA is NOT translated into protein but plays a role in gene regulation?

Accepted Answer

microRNA (miRNA)

Question 20

A patient has a mutation that prevents the addition of the poly-A tail to mRNA. What is the most likely consequence?

Accepted Answer

The mRNA will be rapidly degraded in the cytoplasm.

Transcripción y Regulación de la Expresión Génica: Estructura y Función del Genoma Humano

Study Guide - Practice Questions