Q: If a DNA sequence is $$5'\text{–}ATGCGTACC\text{–}3'$$, what is the corresponding mRNA sequence produced during transcription?

$$5'\text{–}AUGCGUACC\text{–}3'$$

Q: If the mRNA codon is $$5'\text{–}AUG\text{–}3'$$, what is the corresponding anticodon on the tRNA?

$$3'\text{–}UAC\text{–}5'$$

Question 1

Which of the following best describes the Central Dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into proteins.

Question 2

A mutation in the gene encoding enzyme 2 of the arginine biosynthesis pathway in Neurospora crassa prevents the organism from growing unless which of the following is supplied?

Accepted Answer

Arginine

Question 3

Which property of the genetic code allows more than one codon to specify the same amino acid?

Accepted Answer

Redundancy (degeneracy)

Question 4

If a DNA sequence is $$5'	ext{–}ATGCGTACC	ext{–}3'$$, what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{–}AUGCGUACC	ext{–}3'$$

Question 5

Which of the following statements about genes is FALSE?

Accepted Answer

Genes are always identical between individuals of the same species.

Question 6

A scientist discovers a new organism and finds that its genetic code uses triplets of nucleotides to specify amino acids, just like in humans. What property of the genetic code does this illustrate?

Accepted Answer

Universality

Question 7

Which molecule acts as the intermediary between DNA in the nucleus and protein synthesis at the ribosome?

Accepted Answer

mRNA

Question 8

A mouse has a mutation in the melanocortin receptor gene that changes a single amino acid from arginine to cysteine. This results in a lighter coat color. What does this example best illustrate?

Accepted Answer

A single change in DNA sequence can cause a significant change in phenotype.

Question 9

Which of the following best defines a gene?

Accepted Answer

A sequence of DNA that codes for a protein.

Question 10

During translation, what is the role of tRNA?

Accepted Answer

To bring amino acids to the ribosome according to the codon sequence.

Question 11

If the mRNA codon is $$5'	ext{–}AUG	ext{–}3'$$, what is the corresponding anticodon on the tRNA?

Accepted Answer

$$3'	ext{–}UAC	ext{–}5'$$

Question 12

Which of the following is NOT a characteristic of the genetic code?

Accepted Answer

It is ambiguous.

Question 13

A researcher uses a loss-of-function approach to study a gene in yeast. What is the most likely outcome of this experiment?

Accepted Answer

The gene is knocked out, and the resulting phenotype reveals the gene's function.

Question 14

Which of the following best explains why the genetic code is described as 'conservative'?

Accepted Answer

The first two bases in codons that specify the same amino acid are usually identical.

Question 15

Given the mRNA sequence $$5'	ext{–}CUGAAUGCCCAAUAGUGAU	ext{–}3'$$, how many amino acids will be in the resulting polypeptide (excluding the stop codon)?

Accepted Answer

6

Question 16

Which enzyme is responsible for synthesizing RNA from a DNA template during transcription?

Accepted Answer

RNA polymerase

Question 17

A patient has a genetic disease caused by a mutation that prevents proper splicing of mRNA. At which stage of gene expression does this defect occur?

Accepted Answer

RNA processing

Question 18

Which of the following scenarios best illustrates the 'one-gene, one-enzyme' hypothesis?

Accepted Answer

A mutation in a gene leads to the loss of a specific enzyme in a metabolic pathway.

Question 19

If a codon in mRNA is $$5'	ext{–}UAA	ext{–}3'$$, what is its function during translation?

Accepted Answer

It signals the termination (stop) of translation.

Question 20

Which of the following best describes the relationship between genotype and phenotype?

Accepted Answer

Genotype is determined by the sequence of DNA bases, and phenotype is the product of the proteins produced.

How Genes Work: The Central Dogma and Genetic Code

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