Chapter 16 Flashcards
(27 cards)
What are structural genes?
Genes that encode proteins that are used by the cell
Regulatory Genes?
Genes that interact with DNA sequences and affect the transcription and translation of those sequences
Regulatory elements
DNA sequences that are not transcribed but regulate other sequences
What is constitutive expression?
Continuously expressed under normal cellular conditions
What is positive control?
Stimulates gene expression
What is negative control?
Inhibits gene expression
What are domains of regulatory genes?
60-90 amino acids responsible for binding to DNA
What are motifs?
Structures of regulatory proteins that fit into major groove of DNA
What is an operon?
A transcription unit that consists of a promoter, operator, and structural genes
What are indicubible operons?
Transcription usually off, needs to be turned on
What are repressible operons?
Transcription usually on, needs to be turned off
In what type of control does a regulatory protein act as a repressor
Negative Control
In what type of control does a regulatory protein act as an activator
Positive control
Regulatory genes in lac operon of e.coli?
lacP: promoter
lacO;operater
lack; repressor
What type of operon is the lac operon?
Negative Inducible (usually off and needs to be turned on) Regulatory protein is a repressor
What happens to lac operon in absence of lactose?
LacI encodes repressor that binds to operator and blocks transcription
What happens to lac operon when lactose is present?
Lactose turns into allolactose and blocks the repressor from attaching to the lac operator
Catabolite repression is a n example of ____ control
Positive
What does CAP bind with?
cAMP
How are cAMP and glucose related?
Inversely
What happens to the lac operon when glucose is low?
cAMP is high, binds to operator, lots of transcription
What happens to the lac operon when glucose is high?
Little transcription, as low levels of cAMP are present
The trp operon is what kind of operon?
Negative Repressible
What happens in the trp operon when tryptophan is low?
The repressor protein can’t bind to the operator, transcription occurs
