Chapter 5c: Regulation of Gene Expression Flashcards
A given cell transcribes only a specific set of __ and not others (i.e. Insulin is made by pancreatic cells)
* Therefore, gene products should be released at the __ __, in the __ __, and in the __ __
- genes
- right time
- right place
- right amounts
Gene regulation occurs primarily at the level of __ or production of __
- transcription
- mRNA
What is the primary purpose of gene regulation in prokaryotes? (2)
- growth
- response to environment
Who proposed the operon model and when?
Francis Jacob and Jacques Monod proposed the operon model in 1961.
a cluster of genes encoding related enzymes that are regulated together.
operon
Gene control that involves an inhibitor (repressor) that keeps transcription turned off until an anti-inhibitor called inducer turns the system on.
Negative regulation
Gene control that involves an effector molecule (protein, small molecule, or molecular complex) that activates a promoter.
Positive regulation
Two Categories of Gene Control (2)
- Negative regulation
- positive regulation
Two Types Of Proteins In Bacterial Cells (2)
- structural proteins
- regulatory proteins
a protein that do not regulate transcription. Examples include enzymes, membrane proteins, and ribosomal components.
structural proteins
Examples of structural proteins (3)
- enzymes
- membrane proteins
- ribosomal components.
A protein that helps sense the environment and regulate the rate of transcription of structural genes by binding to DNA.
regulatory proteins
In which organism has gene regulation been well studied?
E. coli
What does a bacterial cell do when it encounters a potential food source?
It manufactures the enzymes necessary to metabolize that food.
Who studied the ability of E. coli to digest lactose and when?
Jacques Monod and Francois Jacob studied this in 1959.
What enzyme does E. coli make in the presence of lactose?
Beta-galactosidase.
What is the function of beta-galactosidase?
breaks down lactose so E. coli can digest it for food.
Which gene in E. coli codes for beta-galactosidase?
LAC Z gene
Why does E. coli not produce beta-galactosidase in the absence of lactose?
no point in making the enzyme if there is no lactose to break down
a set of genes in E. coli that are involved in the metabolism of lactose.
lactose operon
What genes are included in the lactose operon? (3)
- lacZ gene
- lacY gene
- lacA gene
regulated by a repressor protein that binds to the operator region, preventing transcription when lactose is not present.
lactose operon
Lactose operon: When __ is present, it binds to the __, causing it to change __ and __ from the operator, allowing transcription of the operon genes.
- lactose
- repressor
- shape
- release
The lac operon promoter sequence is __/___, which is a weak promoter with a basal expression level.
TTTACA/TATGTT
