Question 1

Which of the following best describes the concept of 'alternative splicing' in eukaryotic gene expression?

Accepted Answer

A mechanism by which a single gene can produce multiple different proteins by varying the inclusion of exons and introns in the final mRNA transcript.

Question 2

In the traditional view of gene expression, what is the relationship between genes and proteins?

Accepted Answer

One gene codes for one protein.

Question 3

Which of the following statements about introns is TRUE?

Accepted Answer

Introns are segments of a gene that are typically removed from the mRNA transcript during splicing.

Question 4

Exons can contain special sequences called ESEs and ESSs. What is their function?

Accepted Answer

They indicate whether an exon should be included or excluded in the final mRNA transcript.

Question 5

Which type of alternative splicing is most likely to result in the retention of an intron in the final mRNA transcript?

Accepted Answer

Retained intron

Question 6

A mutation changes the sequence 'UUUGGG' to 'UUUGGC' in an exon. If this sequence is both an ESE and codes for two amino acids, what could be the consequence?

Accepted Answer

The ability for an SR protein to bind may be lost, potentially excluding the exon from the final mRNA and altering the amino acid sequence of the protein.

Question 7

Which of the following is a plausible outcome of a 'silent' (synonymous) mutation within an ESE sequence?

Accepted Answer

Altered splicing, potentially leading to exclusion of the exon and a different protein sequence, despite the codon still coding for the same amino acid.

Question 8

SR proteins play a critical role in alternative splicing. Which statement best describes their function?

Accepted Answer

SR proteins bind to ESEs to promote exon inclusion in the final mRNA transcript.

Question 9

Why can the same gene produce different proteins in embryonic brain cells compared to adult brain cells?

Accepted Answer

Different collections of SR proteins in embryonic and adult brain cells lead to different patterns of exon inclusion, resulting in different protein products.

Question 10

Which of the following equations best represents the number of possible protein isoforms ($$N_{isoforms}) $$that can be produced from a gene with $$n$$ alternatively spliced exons, assuming each exon can be either included or excluded independently?

Accepted Answer

$$N_{isoforms} = 2^n$$

Question 11

A patient with cystic fibrosis has a mutation that alters a splicing cue in the CFTR gene. What is the most likely molecular consequence?

Accepted Answer

The mutation may cause an exon to be skipped, resulting in a truncated or dysfunctional CFTR protein.

Question 12

Which of the following is TRUE regarding mutually exclusive exon retention?

Accepted Answer

Only one of the two exons is included in the final mRNA transcript, never both.

Question 13

Which of the following best explains why alternative splicing increases protein diversity in eukaryotes?

Accepted Answer

It allows for the inclusion or exclusion of different exons, resulting in mRNAs that code for proteins with different amino acid sequences.

Question 14

Which of the following is NOT a type of alternative splicing?

Accepted Answer

Gene duplication

Question 15

If a synonymous mutation occurs in an ESS sequence, what is the most likely effect?

Accepted Answer

It may suppress the inclusion of the exon in the final mRNA transcript, potentially altering the protein product.

Question 16

Which of the following statements about splicing in plants and unicellular eukaryotes is correct?

Accepted Answer

Introns can sometimes be included in the final mRNA transcript.

Question 17

A gene contains 4 exons, and exon 2 can be either included or skipped during splicing. How many different mRNA transcripts can be produced from this gene?

Accepted Answer

$$2$$

Question 18

Which of the following is a direct result of a mutation that disrupts an ESE sequence in an exon?

Accepted Answer

The exon may be excluded from the final mRNA transcript, potentially changing the protein's amino acid sequence.

Question 19

Which of the following best describes the role of the spliceosome in gene expression?

Accepted Answer

It binds to short sequences at the ends of introns and removes them from the primary RNA transcript.

Alternative Genome: Mechanisms and Implications of Alternative Splicing

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