RNA Synthesis and Gene Regulation

These flashcards cover key concepts related to RNA synthesis and gene regulation as per the provided lecture notes.

What enzyme catalyzes RNA synthesis in prokaryotes?

RNA polymerase.

What type of RNA does a single prokaryotic RNA polymerase synthesize?

All types of RNA including rRNA, tRNA, and mRNA.

In what direction is the RNA strand extended during synthesis?

5' to 3' direction.

What is the template strand also known as?

The nonsense strand.

What is the coding strand also referred to as?

The sense strand.

What two conserved sequences are found in bacterial promoters?

The –35 and –10 regions.

What is required for RNA polymerase to recognize bacterial promoters?

Sigma subunit.

What's the role of the Rho factor in transcription termination?

It tracks along the nascent transcript and causes termination by melting the RNA:DNA duplex.

What is the function of activator proteins like CAP in gene regulation?

They help attract RNA polymerase to weak promoters.

What is the TATA box and its significance?

An AT-rich sequence that serves as a binding site for TATA binding factor (TBF) required for transcription initiation.

How are introns and exons characterized in pre-mRNA?

Introns are intervening sequences that are removed, while exons are the coding sequences that remain.

What happens during mRNA capping in eukaryotes?

A guanylate residue is added to the 5' end, often methylated, to stabilize mRNA.

What are spliceosomes and their role in mRNA processing?

Large complexes of ribonucleoproteins that facilitate RNA splicing.

What is alternative splicing?

A process that allows a set number of genes to encode a greater diversity of proteins.

What is the general structure of a prokaryotic gene?

Contains a promoter, coding region, and a terminator.

What is a promoter's role in gene transcription?

It initiates transcription by providing a binding site for RNA polymerase.

What is the primary difference in RNA processing between prokaryotes and eukaryotes?

Eukaryotic mRNAs undergo extensive processing including capping, polyadenylation, and splicing.

How does glucose availability affect Lac operon expression in E. coli?

If glucose is low, the Lac operon is activated; if glucose is present, Lac expression is repressed.