Module 6 - Regulation of Gene Expression Flashcards
Term used to describe genes that are always active and expressed; are necessary for metabolism and/or production of proteins?
Constitutive Expression
Term used to describe genes expression that can be turned on or off as needed?
Inducible Expression
What controls the initiation of transcription?
Binding of RNA polymerase to the promoter
How do organisms regulate the activity of enzymes?
By altering their structure and therefore their binding properties
What method is used to shut down a pathway?
Allosteric Inhibition
What method is used to regulate enzyme action by adding a chemical entity (Ex: phosphorylation, methylation)
Covalent Modification
What are two ways that enzymes can be quickly deactivated when a rapid response is necessary?
- Allosteric Inhibition
- Covalent Modification
Compared to quickly deactivating enzymes, what is the more efficient way to control metabolic pathways?
Regulate transcription of the genes that encode these enzymes
What two factors does regulating the transcription of genes help save?
- Energy
- Resources
What does the production of an enzyme begin with?
Gene transcription
What occurs as a result of gene transcription?
mRNA is translated subsequently to protein
Regulatory molecules and DNA-binding proteins affect the ability of what?
RNA polymerase to bind to the promoter on DNA
What does the binding of RNA polymerase to the promoter on DNA affect?
The amount of transcription that occurs
What two things are not produced when transcription is prevented?
mRNA and proteins
Is gene expression controlled only at a select level or several levels?
Several
- Control of transcription
- Control of translation
- Activation/inhibition of final gene product
What is another term for the start of a gene in which RNA polymerase binds to DNA?
Promoter
Will RNA polymerase bind more well or less well to weak promoters?
Less well
Term used to describe those with sequences that differ from the optimal sequence, resulting in a low basal level of activity?
Weak promoters
What protein can increase the binding of RNA polymerase to weak promoters?
Activator proteins
What protein can obstruct the binding of RNA polymerase to promoters?
Repressor proteins
What is a transcriptional unit also called?
Operons
What two things does an operon need to consist of?
- Consecutive series of structural genes that code for polypeptides, transcribed from a single promoter
- Regulatory DNA elements that affect their transcription
Polycistronic operons encode for how many polypeptides?
More than one
How many polypeptides does mRNA transcript code for in eukarya?
1
What are the three structural genes that make up a lac operon? In addition to what other factor?
- lacZ
- lacY
- lacA
- Operator
What is the term for the DNA sequence to which regulatory proteins can bind?
Operator
What is the product and function of lacZ gene?
- Permease
- Facilitates the uptake of lactose
What is the product and function of lacY gene?
- B-galactosidase
- Facilitates enzymatic breakdown
What is the product and function of lacA gene?
- B-galactoside transacetylase
- Unknown role
What controls the initiation of transcription in an operon?
Single promoter
What binds to the operator along with associated effector molecules and modulate the ability of RNA polymerase to bind to the promoter and initiate transcription?
Regulatory proteins
What is it called when regulatory proteins can inhibit operon transcription?
Negative control
What is it called when regulatory proteins can facilitate operon transcription?
Positive control
What two things do higher rates of transcription result in?
- Higher levels of mRNA transcript
- Protein production
What type of control involves regulatory mechanisms that involve a repressor?
Negative control
What action inhibits the binding of RNA polymerase to the promoter in negative control?
Repressor binding to the operator
Molecules that are intermediates of the related metabolic pathways are called?
Effectors
Effectors interact with repressor proteins and modulate their ability to bind to the operator. This is known as what kind of regulation?
Allosteric regulation
What are two kinds of effector molecules?
- Inducers
- Compressors
Effector molecule that inhibits the binding of the repressor protein to the operator?
Inducers
Effector molecule that enhances binding of the repressor to the operator?
Corepressors
Does a presence or absence of lactose block the promoter site when the repressor binds to the operator?
Absence
Presence or absence of lactose? Allolactase (metabolite of lactose) binds to the repressor, preventing binding to operator.
Presence
