RNA

Question 1

Q: What is transcription and what are its main steps?

Answer 1

A:
Transcription is the process of copying a gene’s DNA sequence into RNA.
Steps:

Initiation – RNA polymerase binds to the promoter and unwinds DNA

Elongation – RNA polymerase builds RNA by adding complementary RNA nucleotides

Termination – RNA polymerase reaches a stop signal and releases the RNA strand

In eukaryotes, the RNA is processed (capping, splicing, poly-A tail) before translation.

Question 2

Q: What does RNA polymerase do during transcription?

Answer 2

A: RNA polymerase copies the DNA template strand to synthesize a complementary RNA strand, using uracil (U) instead of thymine (T) and ribose sugar instead of deoxyribose.

Question 3

Q: How does RNA polymerase find the start of a gene and transcribe in the correct direction?

Answer 3

A: RNA polymerase binds to the promoter region upstream of a gene. It then begins transcription at the start site, reading the template strand in the 3’ to 5’ direction to make RNA in the 5’ to 3’ direction.

Question 4

Q: How are RNA transcripts processed in eukaryotic cells?

Answer 4

A: Pre-mRNA is processed by:

5’ capping

3’ poly-A tail addition

Splicing (removal of introns)
Then, mature mRNA is transported from the nucleus to the cytoplasm for translation

Question 5

Q: What features define a mature mRNA transcript?

Answer 5

A: A mature mRNA has:

A 5’ cap

A 3’ poly-A tail

A start codon (usually AUG)

A stop codon (e.g., UAA, UAG, UGA)

Coding sequence between the start and stop codons