RNA and protein synthesis

All of these RNAs are non-protein coding except for

• tRNA

• mRNA

• rRNA

• small nuclear RNA

The non-protein coding segments of a gene are known as

• Exons

• Introns

Answer explanation

Introns are also known as intervening sequences. They do not code for proteins.

Match the following with the correct process

• DNA to DNA

• Translation

• RNA to protein

• Transcription

• DNA to RNA

• Replication

Which of the following is not involved in protein synthesis (translation) ?

• RNA polymerase

• mRNA

• tRNA

• Ribosomes

Answer explanation

RNA polymerase is a key player in transcription, which takes place in the nucleus

which of the following statements is FALSE regarding DNA transcription?

• No primer is required

• DNA is synthesized in the 5' to 3' direction

• RNA polymerase is the main transcription enzyme

• The coding strand is identical to the mRNA molecule

Answer explanation

RNA is synthesized in transcription NOT DNA. DNA is synthesized in DNA replication

Which of the following is the TEMPLATE strand for this mRNA molecule?

5- AAA UUU GGC -3

• 3- UUU AAA CCG -5

• 3- TTT AAA CCG -5

• 5- TTT AAA CCG -3

• 5- AAA TTT CCG -3

Answer explanation

TEMPLATE strand is complementary to the mRNA molecule, which means the strand must be in the opposite direction. The coding strand is identical to mRNA (except that uracil is replaced with thymine)

3' end capping is a post-transcriptional modification of mRNA that

• Adds a methylated guanine to the 3' end of mRNA

• adds adenosine nucleotides to the 3' end of mRNA

• removes the introns and joins the exons together

Answer explanation

5' end capping adds a methylated guanine to the 5' end of mRNA

which part of the mature mRNA transcript protects from 3' to 5' exonucleases ?

• 5' methylated guanine

• introns

• exons

• 3' poly A tail

Arrange the answers in the correct sequence of protein synthesis

• Charging of tRNA

• Initiation with a start codon

• elongation

• termination with a stop codon

which antibiotic inhibits the binding of aminoacyl tRNAs to the A site in bacterial ribosomes?

• chloramphenicol

• macrolide antibiotics

• tetracycline