Cell Bio- Ch. 7 Gene Expression

What process uses RNA as a template for synthesis?

Transcription

The three types of RNA polymerases in eukaryotes produce different RNA types. Which polymerase is the most active?

RNA polymerase I

The strand of DNA that is used as a template during transcription is called what?

Template Strand

What modifications are made to eukaryotic mRNA before nuclear export?

5' cap addition and Poly-A tail addition

What is the name for the sequences that signal the start and end of transcription in DNA?

Transcription start and stop sites

Which nitrogenous base is found in RNA but not in DNA?

Uracil

What is the function of sigma factors during transcription?

They recruit RNA polymerase during bacterial transcription.

What is the purpose of the 5’ cap in eukaryotic mRNA?

It protects mRNA from degradation and assists with ribosome binding.

Which enzyme is responsible for catalyzing RNA synthesis?

RNA polymerase

What occurs during splicing in eukaryotic mRNA processing?

Introns are removed and exons are joined together.

What is alternative splicing?

The process that allows different mRNAs to be produced from the same primary transcript.

What is the start codon for translation?

AUG

How does a tRNA molecule read the genetic code?

By pairing its anticodon with the corresponding codon on the mRNA.

What are the three binding sites on a ribosome?

A site (aminoacyl), P site (peptidyl), E site (exit).

What is the primary role of aminoacyl-tRNA synthetases?

To charge tRNA with the appropriate amino acid.

What marks the translation termination process?

Recognition of stop codons by release factors.

Polycistronic mRNAs can contain what?

Multiple start sites and can encode multiple proteins.

What role do small nuclear RNAs (snRNAs) play in splicing?

They partner with proteins to form small nuclear ribonucleoproteins (snRNPs) that help remove introns.

What is the significance of the 'bottlebrush appearance' mentioned in the context of RNA transcripts?

It refers to the structure of multiple RNA transcripts being transcribed in series.

What happens when the tail domain of RNA polymerase is phosphorylated?

It releases RNA polymerase from the initiation complex and generates docking sites for RNA processing enzymes.