Ch.11 How Genes Are Controlled Flashcards
Proteins interact with DNA and turn prokaryotic genes on or off in response to ______ ____.
Environmental changes
The turning on and off of genes is called? It helps organisms respond to environmental changes.
Gene regulation
In gene regulation the genes determine the sequence of what?
The nucleotide sequence of specific messenger RNA molecules
In gene regulation mRNA determines the sequence of what?
Determine the sequence of amino acids in protein molecules
What does a gene that is turned on do?
It is being transcribed into mRNA with the message being transcribed into specific proteins molecules.
This is the overall process by which genetic information flows from genes to proteins-genotype to phenotype. It makes it possible for cells to provide specific kinds of proteins when and where they are needed.
Gene expression
Most enzymes are proteins and their production is an outcome of ____ _____.
Gene expression
These are short sections of DNA that help control the expression of these genes.
Control sequences
These are the site on a control sequence where the transcription enzyme, RNA polymerase, attaches and initiates transcription.
Promoter
This is a switch between the promotor and the enzyme genes. It determines whether RNA polymerase can attach to the promoter and start transcribing the genes
Operator
This is a cluster of genes with related functions along with the control sequence.
Operon
Operons only exist in _____.
Prokaryotes
A single on/off switch can control what?
The whole gene cluster of an operon.
When an operon is turned off what happens to transcription?
Transcription is turned off because of the repressor.
What is a repressor and what does it bind to?
The repressor physically blocks the attachment of RNA polymerase to the promotor. It binds to the operator.
This codes for the repressor and is where the repressor comes from. It is located outside the operon.
Regulatory gene
What happens when the operon is turned on?
- Lactose interferes with the attachment of the repressor by binding to it and changing its shape.
- The switch remains open because the repressor cannot bind to the operator.
- RNA polymerase is then able to bind to the promotor and transcribe the genes of the operon.
mRNA has multiple codons signaling the ____ and ____ of translation.
Start and stop
This is an operon that is usually turned off but can be stimulated by a molecule
Inducible operon
This type of operon is normally turned on but can be inhibited when a specific molecule is present in abundance.
Repressor operon