Chapter 12/13: eukaryotic regulation and development

What different between positive regulation and negative regulation?

Positive regulation uses activators while negative regulation uses repressor proteins

How can transcription factors influence gene expression?

They can play either a positive role using activators or a negative role using repressor

What do transcription factors (TF) bind to?

They bind to the proximal enhancer region that is located near the promoter region

Why is the binding of TF to the proximal enhancer region important?

They help promote transcription to occur due to more work required for gene expression to occur in eukaryotes

Why are GTFs required to bind to the core promoter region?

They help prepare the promoter region for RNA polymerase to bind to and begin transcription

What are distal enhancers?

A type of enhancer that uses TF to regulate different groups of genes depending on how the chromosome is organized spatially

Where are distal enhancers located?

They are located hundreds of thousands of base pairs upstream or downstream from the transcription start site

Why do eukaryotes contain distal enhancers?

Due to the genomes being more complex with a vast majority being noncoding that contains functional elements

What were to happen in the absence of proximal enhancers or core promoter region?

Gene transcription or gene expression is drastically reduced by 80%

How do distal enhancers allow for TF to communicate with RNA polymerase in the core promoter?

They fold and loop back in order to be in close vicinity of the core promoter, letting TF bind and be able to communicate with RNA polymerase through the mediator protein, allowing for gene expression to be regulated

What are mediators?

They are protein complexes that contain multiple subunits that bind with RNA polymerase and sometimes TF

What are transcription factors?

They are a complex containing stretches of amino acids, with an N-terminus and C-terminus, that each fold independently into a their own 3D space that make up 4 separate domains

What are the 4 domains in transcription factors?

• DNA binding domain

• Dimerization domain

• Ligand binding domain

• Activation/repression domain

What is the DNA binding domain?

A domain that consists of folded regions and has the ability to recognize specific nucleotide sequences

What is the dimerization domain?

A domain that allows for 2 TF together and form a dimer in order to regulate gene expression

What is the ligand binding domain?

A domain that determines how the TF responds to environmental cues or physiological cues and when the TF is needed

What is the activation/repression domain?

A domain that stretches the amino acids of TF when folded in order to allow TF to interact with transcription machineries and determine whether it has a positive or negative impact on transcription

What is the galactose pathway?

A system discovered in yeast that drives gene expression by either using galactose to activate gene expression using galactose or by removing galactose to silence gene expression