DNA Repair Mechanisms and Transcription Processes

These flashcards cover DNA repair mechanisms, types of DNA damage, and key aspects of prokaryotic and eukaryotic transcription processes.

What are the main types of DNA repair mechanisms?

Direct reversal, Replacement (base excision, nucleotide excision, mismatch repair), Recombination repair, Non-homologous end joining, Resynthesis of replacement DNA.

What types of DNA damage can occur?

Single base changes, structural distortion mutations.

What is Mismatch Repair?

A repair system that corrects mismatches by recognizing and repairing incorrect base pairings during DNA replication.

What is the significance of the Umu System?

An error-prone repair mechanism activated in response to DNA damage, allowing some mismatches to be incorporated to help cells survive.

What is the role of RecA in DNA repair?

RecA induces the SOS response during DNA damage, enabling repair mechanisms to function.

What is Non-Homologous End Joining (NHEJ)?

A pathway for repairing double-stranded breaks in DNA, which does not require a homologous template.

What are Drosophila P-elements?

Transposable elements that can produce different RNAs and play a role in hybrid dysgenesis by affecting transposase activity.

How do intrinsic terminators function in transcription?

Intrinsic terminators form hairpin structures in RNA and cause RNA polymerase to stall and dissociate from the DNA.

What triggers RNA polymerase to begin transcription?

The binding of transcription factors to the promoter region allows RNA polymerase to initiate transcription at the startpoint.

What are RNA polymerase I, II, and III responsible for transcribing?

RNA polymerase I transcribes rRNA, II transcribes protein-coding genes and certain non-coding RNAs, and III transcribes tRNA and small nuclear RNAs.

What is the function of the TATA box in transcription?

It is a conserved sequence found in eukaryotic promoters that helps recruit transcription factors and RNA polymerase.

What happens during the promoter clearance stage of transcription?

RNA polymerase moves past the promoter after synthesizing approximately 9 nucleotides, releasing abortive products before continuing elongation.

What is the purpose of the carboxy-terminal domain (CTD) in RNA polymerase II?

The CTD is involved in RNA processing events, such as capping, splicing, and polyadenylation.