Topic 4: Transcriptional Regulation and Epigenetics Flashcards
Describe the lac operon and the transcription of its genes is regulated by lactose availability
A series of genes side by side. Upstream of the DNA sequence is the repressor. If something is bound to it, it means nothing can be bound to the lac operon. So lactose is unavailable. When lactose is available, it can bind to the repressor, which means the repressor can not bind to the operator, and the lac operon can be expressed.
How is cAMP made?
???
How does Glucose prevent transcription of the lac operon?
Many cells prefer glucose over other sugars. Lac operon is repressed in the presence of glucose because it wants to use glucose first, so not transcription of lac operon happens because glucose is not metabolized.
Define enhancers, what is their roles in transcription?
Sequences that interact with polymerase and allow for more efficient transcription. Have sequences that allow for multiple TF to bind .
What is cohesion and what role does it play in transcription?
Loop piece of DNA and use cohesins to hold together to get sequences to interact with each other to form transcription machinery.
What are negative regulatory factors?
NELF and DSIF, pause transcription soon after intiation
What are positive regulatory factors?
when the time is right they re-initiate transcription
How does chromatin condensation suppress transcription?
for transcription to happen need to uncoil parts of the DNA you need to express and condense parts you don’t want to be expressed. If chromatin is condensed, RNA polymerase can not reach DNA to transcribe it.
What is the effect of histone acetylation on transcription?
causes chromatin to decondense leading to increased transcription. Polymerase can reach DNA easier.
How do chromatin remodeling factors work?
work by moving, removing, or exchanging histones to make DNA more visible.
what is the effect of DNA methylation on transcription?
makes it more unlikely DNA sequence will be transcribed. Can also be inherited during replication.
What is the importance of passing epigenetic changes to cells after DNA replication?
Helps regulate gene expression because you don’t need all genes to be active in all cells. Important for evolution.
