Control of Gene Expression in Prokaryotes and Eukaryotes

The process of how to control gene expression in prokaryotes. vocab and conceptual knowledge.

18 cards   |   Total Attempts: 182
  

Cards In This Set

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Operon
Group of structural genes plus sequences that control transcription
Regulator Gene
Encodes the regulator protein or RNA, product has regulatory role. helps to control the transcription of the structural genes of the operon. NOT part of the operon
Regulatory Gene
Genes whose products, RNA or Proteins, interact with other sequences and affect the transcription or translation of those sequences
Regulatory Element
DNA sequence that is not transcribed, sequence has regulatory role (serves as binding site) they affect the expression of sequences to which they are physically linked.
Constitutive Gene
Gene that is not regulated and is continually expressed
Structural Genes
Encode the proteins used in metabolism or biosynthesis--non regulatory
Polycistronic mRNA
Single bacterial RNA molecule that encodes more than one polypeptide chain, uncommon in euks. MANY GENES/transcript that share a pathway and are all terminated by the same terminator sequence-EFFICIENT
Negative Control
Regulatory protein is a repressor (Regulatory element effects the expression of sequences to which they are physically linked)
Positive Control
Regulatory protein is an activator
Inducible Operon
Transcription is normally off and something must happen to induce transcription to turn it on.
Repressible Operon
Transcription is normally on and something must happen to repress transcription, to turn it off
Negative inducible Operon
In the absence of inducers, Transcription and translation of the regulator gene produce an active regulator protein (repressor) that readily binds to the operator and prevents transcription of the structural genes.
If an inducer is present, the inducer binds to the active regulator protein and alters the shape of this repressor (allosteric protein) which is then unable to bind to the operator, transcription will take place because RNA polymerase binds to the operator.
How does a repressor work?
Operator site overlaps the promoter site and the biding of the regulator protein to the operator physically blocks the binding of the RNA polymerase to the promoter and prevents transcription
Corepressor
Small molecule that binds to the repressor and makes it capable of binding to the operator
Inducer
Small molecule that binds to the repressor and turns transcription on by altering the shape of the active regulator protein(repressor) thereby making the regulator unable to bind to the operator so RNA polymerase binds, thus, inducer increases transcription