Transcriptional Regulation Prokaryotes

Prokaryotes mainly control their gene expression at what level

Transcriptionally

Eukaryotes mainly control their gene expression at what level

Post-transcriptionally

Genes expressed in all conditions are

Constitutive

Genes expressed in some conditions are

Inducible/repressible

The most important aspect of gene regulation in bacteria is

initiation of transcription

Genes in a regulatory system that encode proteins that function in metabolism, biosynthesis, or structural aspects of the cell. (LacZ, lacY, lacA in lac operon)

Structural genes

Genes in a regulatory system that encode regulatory RNAs or proteins that control expression of structural genes. (LacI in lac operon)

Regulatory genes

Sequence in a regulatory system that is not transcribed but regulates other genes, usually the binding site of regulatory proteins. (promoter, operator, and CAP-binding site in lac operon)

Regulatory elements

To determine positive vs negative control, look at whether the _____ ______ stimulates or inhibits expression when bound to regulatory sequences.

Regulatory protein

Regulatory proteins are inducible/repressible or constitutively expressed?

Constitutively

To determine inducible vs repressible expression, look at how the presence of ___ _____ affects whether transcription is active or inactive.

The effector

Inducible vs repressible:
Presence of the effector enables transcription

Inducible

Inducible vs repressible: Presence of the effector blocks transcription

Repressible

Set of functionally related structural genes transcribed from a single promoter

Operon

Cis-acting regulatory sequence where the trans-acting regulatory protein (activator/repressor) binds to the DNA and affects transcription

Operator

The region that binds RNA polymerase in an operon

Promoter

Protein that is usually expressed on a separate gene that the rest of the operon

Regulatory protein

Which protein product of the lac operon is responsible for actively transporting lactose into the cell

Permease

Which protein product of the lac operon is responsible for breaking down lactose into galactose and glucose

beta-gal

LacY encodes

permease

lacZ encodes

beta-gal

lacA encodes

transacetylase

The lac regulatory region is made of

LacP, lacO, CAP site

The negative regulator of the lac operon is

lac repressor

The positive regulator of the lac operon is

cAMP-CAP

The lac operon is inducible or repressible expressed

inducible

The effectors in the negative regulation of the lac operon are

Allolactose or IPTG

The effector in the positive regulation of the lac operon is

glucose

Low glucose means what levels for cAMP

High

High levels of glucose means what for cAMP

low

low cAMP-CAP levels means transcription is more or less activated

Less

high cAMP-CAP levels means transcription is more or less activated

More

Mutant in lac operon that would lead to no expression of ANY of the lac structural genes

lac P -

Mutant in lac operon regulatory gene that would lead to constitutive expression of all lac structural genes

Lac I -

Mutant in lac operon that would make the repressor unable to bind to allolactose, thus always bound to lacO

lac S

Mutant in lac operon that would cause constitutive expression, even in the presence of a superrepressor

lac O c

Tryptophan is synthesized by _ structural genes

5

The trp operon is gene control is (pos/neg + rep/ind)

negative repressible

No tryptophan present means trp genes (are/aren’t) expressed

are

Tryptophan present means trp genes (are/aren’t) expressed

Aren’t

The trp operon has a repressor or activator

repressor

The effector of the trp operon is

Tryptophan