Chapter 12: Control of Gene Expression Flashcards
Define operon
a group of genes that share a common promoter and are transcribed as a unit, producing a single mRNA molecules that encodes several proteins
T/F: Operons control the expression of genes
True
True/False: Operons are common in bacteria, archaea, and eukaryotes.
False. Operons are common in bacteria and archaea but not as common in eukaryotes
Define gene regulation
Encompasses the mechanisms and system that control the expression of genes
How does gene regulation help bacteria?
By providing internal flexibility, turning genes on and off in response to environmental changes
Define central dogma
Genetic information flows from DNA to RNA to proteins.
How does gene regulation help multicellular eukaryotic organisms?
By bringing about cellular differentiation
Define structural genes
Encode proteins used in metabolism or biosynthesis or that play a structural role in the cell.
Define regulatory genes
Either RNA or proteins, interact with other DNA sequences and affect the transcription or translation of those sequences
The products are regulatory genes are often…
DNA-bonding proteins or RNA molecules that affect gene expression
Define constitutive genes
Structural genes that encode essential cellular functions and are expressed continually and are not regulated
Define regulatory element
DNA sequences that are not transcribe, bit still affect the expression of DNA sequences to which they are physically linked
Control is involved in gene expression. What are the two types of control?
Positive control and negative control
Define positive control
Processes that stimulate gene expression
Define negative control
Processes that inhibit gene expression
At what levels can gene expression be controlled?
Any number of levels.
DNA/chromatin structure, transcription, mRNA processing, mRNA stability, translation, posttranslational modification
Why is transcription a particularly important level of gene regulation in both bacteria and eukaryotes?
Transcription is the first step in the process of information transfer from DNA to protein. For cellular efficiency, gene expression is often regulated early in the process of protein production
What is the strucutre of an operon?
A promoter and a regulator which bind to an operator site connected to 3 structural genes
Promoter - regualtor/operator - gene a / gene b / gene c
Define regulator gene
helps control the expression of the structural genes of the operon by increasing or decreasing their transcription
Define regulator proteins
Can bind to a region of the operon called the operator and affect whether transcription can take place
Define operator
A region of the operon that regulator proteins can bind to
What is the difference between a structural gene and a regulator gene?
A. Structural genes are transcribe into mRNA; regulator genes aren’t
B. Structural genes have complex structure; regulator genes have simple structures
C. Structural genes encode proteins that function in the structure of the cell; regulator genes carry out metabolic reactions
D. Structural genes encode proteins used in metabolism or biosynthesis or cell structure; regulator genes control the transcription of structural genes
D
D. Structural genes encode proteins used in metabolism or biosynthesis or cell structure; regulator genes control the transcription of structural genes
What are the two types of transcriptional control?
Postitive control and negative control
What is negative control regarding transcriptional control
A regulator protein is a repressor, binding to DNA and inhibiting transcription.