Gene Regulation

Prokaryote Gene Regulation

100

Tryptophan is in the system and stops transcription of tryptophan-synthesizing enzymes. This is repressible or inducible gene expression?

What is repressible

200

This is what an operon is composed of

What is promoter, operator, and genes of interest

300

Genes under the control of the same promoter and transcribed into one continuous mRNA strand.

polycistronic mRNA

400

When lactose is in the system, lac genes are turned on in a prokaryote. Briefly describe how this happens.

Inducible transcription. Lactose is an inducer and changes the shape of the repressor which falls off of the operator. RNA polymerase is then able to transcribe the genes to produce the proteins used to digest lactose.

500

What protein does allolactose bond to?

How does this change the location of the enzyme-substrate?

binds to the repressor protein

repressor with allolactose changes shape and moves from the operator site. 

Post-translation

100

Post translational mods impact what molecular structure?

proteins 

300

Why are post-translational mods necessary in eukaryotes?

Polypeptides synthesized in eukaryotic cells are usually inactive ollowing synthesis.

400

Give an example of a post-translational modification 

covalent linkage of phosphate group to amino acid group

500

Describe the post-translational modifications that occur to insulin 

insulin is initially folded into 3D

structure. However, to be active, several amino

acids are removed, leaving 2 polypeptide chains. The chains are combined via a covalent bond

between two sulfur atoms on each chain.

Pre-transcription

100

What's another word for pre-transcriptional mods

Chromosomal 

200

Why is chromatin a physical barrier for enzymes that want to initiate transcription

(Remember what you did with Ms. Fugler)

supercoiled, no access. 

300

What structure do pre-transcription mods target?

Chromatin structure. 

400

List 2 methods for accomplishing  pre-transcript mods

chemical mods of histones 

chromatin remodelling complexes unwind the chromatin. 

500

This gene is essential for setting up the posterior and anterior ends of certain organisms. Mutations in such a gene can lead to an organism having two tails, for an example.

What is bicoid gene

Transcription

100

are eukaryotic genes organized into operons?

no

200

What unique structure does each gene have to control its transcription

distinct promoter. 

300

Explain the basic level of transcription. 

Transcription factors must interact with

promoter for RNA poly to initiate transcription.

400

Explain the enhanced level of transcriptional mod

(2 points)

Activator proteins enhance transcription: 

1. binding to transcription factors and RNA poly

2. bind to DNA sequences called enhancers 

500

How is transcriptional regulation in eukaryotes highly specific? 

Gene regulation usually requires more than one

activator. Multiple activators allows gene regulation to be highly specific to particular conditions. 

Translational

100

what is the primary mechanism of translational modification? 

RNA interference

200

What are the two RNAs involved in translational mods?

micro RNA (miRNA) and small

interfering RNA (siRNA)

300

How do small RNA's target specific mRNAs?

They form complementary base pairs

400

Explain how the miRNA and siRNA repress gene expression? 

1. promoting mRNA cleavage

2. inhibiting translation.