BIO230: Regulation of Genome Expression - Prokaryotic and Eukaryotic Transcriptional Regulation

These flashcards cover key concepts in prokaryotic and eukaryotic transcription regulation, including mechanisms, examples, and important terminology.

What is the key mechanism by which prokaryotic gene regulation occurs?

Negative regulation involves competition between RNA polymerase and repressor proteins for promoter binding.

What does the Tryptophan repressor do?

It binds to the major groove of DNA and blocks transcription of the tryptophan operon when tryptophan levels are high.

In the context of bacteriophage lambda, what are the two states it can exist in?

Prophage and lytic states.

What triggers the switch from prophage to lytic state in bacteriophage lambda?

The host response to DNA damage.

What are transcriptional circuits and mention two types?

They are regulatory networks that control gene expression, including positive feedback loops and feed-forward loops.

What is synthetic biology in relation to transcriptional circuits?

It involves constructing artificial gene circuits to study their behavior in cells.

What are riboswitches and their role in transcriptional attenuation?

Short RNA sequences that change conformation when bound by a small molecule, causing premature termination of transcription.

What is the effect of guanine levels on purine biosynthetic genes via riboswitches?

High guanine levels bind the riboswitch, causing a conformational change that terminates transcription of purine biosynthetic genes.

What role does the mediator play in eukaryotic transcription?

The mediator acts as an intermediary between regulatory proteins and RNA polymerase to facilitate transcription.

What are the four major ways activator proteins can alter chromatin structure in eukaryotes?

Nucleosome sliding, nucleosome removal, histone exchange, and recruitment of histone modifying enzymes.

Describe the histone code concept. What is its significance?

Specific modifications to histones dictate gene expression patterns, providing a regulatory mechanism through 'writers' (modifying enzymes) and 'readers' (proteins that interpret these modifications).

How do activator proteins influence transcription in eukaryotes?

They can directly attract transcription machinery or indirectly modify chromatin structure to enhance access to DNA.

What is the main difference in transcriptional repression mechanisms between prokaryotes and eukaryotes?

Eukaryotic repressors rarely compete with RNA polymerase for DNA access; instead, they inhibit transcription through various other mechanisms.