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23 Cards in this Set
- Front
- Back
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gene expression
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DNA transcription into RNA then translation to yield specific proteins
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what are the two major approaches to regulate protein function?
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Control activity of an enzyme or other protein
control the amount of the enzyme |
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the activity of a protein can be regulated only after it has been synthesized
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regulating activity of an enzyme is very rapid(seconds or less)
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Synthesizing an enzyme is relatively slow
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several minutes
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how genes are made or expressed..remember
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DNA Is transcribed to rna than translated into protein
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any step along the way can regulate the gene
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post transcriptional post translational
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most proteins are enzymes that carry biochemical reactions
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regulation helps conserve energy and resources
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what are the two major levels of regulation in the cell
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1. one controls the activity of the preexisting enzymes(posttranslational regulation) very rapid process
2. one controls the amount of an enzyme Regulate level of transcription, regulate translation, slower process(minutes) |
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what are the multiple outcomes after dna binding?
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1. dna binding protein may catalyze a specific reaction on the dna molecule( ie transcription by rna polymerase)
2. The binding event can block transcription(negative regulation) deals with arg(arginine) and lac(lactose) operon 3. the binding event can activate transcription( positive regulation) which deals with mal (maltose) |
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the arg and lac operons are examples of negative control because
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a repressor blocks transcription
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in the arg operon the repressor is
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inactive and must be activated to prevent transcription
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in the lac operon the repressor is
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active and prevents transcription
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operon
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a cluster of genes arrange linear whose expression is under control of a single operator
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where is the operator located?
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downstream of the promoter
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what is physically blocked when repressor binds to operator
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transcription
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the addition of what will inactivate the repressor and transcription can proceed
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inducer
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repressor protein
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a regulatory protein that binds to specific sites on dna and blocks transcription; involved in negative control
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Repressor's role is inhibitory so it is called
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negative control
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repression
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prevention of the synthesis of an enzyme in response to a signal
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induction
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production of an enzyme in response to a signal(often the presence of the substrate for the enzyme)
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the amount of an enzyme in the cell can be controlled by decreasing( repression) or increasing (induction) the amount of mrna that encodes the enzyme
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true
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positive control
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regulator protein activates the binding of RNA polymerase to DNA(ex maltose)
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activator proteins bind specifically to certain dna sequences
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they bind to activator binding sites on the dna and stimulate transcriptions
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