Lect 11 - transcription

Flashcards to review the transcription process based on lecture notes.

What is the central dogma of molecular biology?

DNA replicates and can be transcribed to make RNA. RNA replicates can be translated to form a protein. RNA can also replicate and reverse transcribe to make DNA

What is gene expression?

Process by which information from a gene is used in the synthesis of a functional gene product: protein or non-coding RNA

What is a gene?

Defined region of DNA that produces a specific RNA molecule which has some function

What is the first step of Transcription Initiation?

Transcription factors bind to the TATA box and other regions of the promoter.

Why are TATA boxes suitable for Transcription Initiation?

Each having only 2 H-bonds which are weaker and easier to break apart.

What enzyme begins the transcriptional initiation complex?

RNA polymerase II binds to the promoter region of the DNA forming a transcriptional initiation complex together with the transcription factors

What is the role of Helicase in transcription?

Unzips the DNA by breaking H-bonds between the DNA base components.

Which is more transcriptionally active: euchromatin or heterochromatin?

Euchromatin

How does RNA polymerase II work during elongation?

RNA polymerase II uses the template strand (3’ → 5’) as a template and inserts complementary RNA nucleotides in the (5’ → 3’) direction

What is the role of topoisomerase II during elongation?

Releases the tension (supercoil) that builds up ahead of the RNA polymerase due to unzipping.

What are exons?

Sections that will be expressed sequences.

What are introns?

Sections that are intervening sequences and are removed from the preMRNA by splicing.

What are UTRs?

Transcribed but not translated and contain regulatory elements

What is the role of the 5’ G cap?

Prevents degradation, promotes intron excision, provides a binding site for the small ribosomal subunit

What is the role of the poly-A tail?

Prevents degradation, helps mRNA to move from nucleus to cytoplasm

Where does transcription occur in prokaryotes?

Transcription occurs in the cytoplasm.

Where does transcription occur in eukaryotes?

Transcription occurs in the nucleus.