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30 Cards in this Set
- Front
- Back
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Dioxin Growth |
The sequential use of first one sugar and then th tother sugar. In the case of lactose and glucose, glucose is used because lactose must be cleaved before it can be utilized |
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CAP |
- Catabolite Activator Protein - A transcriptional activator involved in the lac operon - It only functions properly when it binds to cAMP. cAMP causes an allosteric transition |
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Allosteric Transition |
The reversible modification of a protein's conformation and function by an effector molecule that binds at a site other than the active site |
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CAP - cAMP Complex |
- Helps in binding of polymerase to promoter - Form of positive regulation |
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Transcription Factors |
Proteins that bind to specific DNA sequences, thereby controlling the rate of transcription of genetic information from DNA to RNA |
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Adenyl Cyclase |
Converts ATP to cAMP |
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Catabolite Repression |
- Presence of glucose inhibits adenyl cyclase which stops cAMP from being produced - Without cAMP, CAP cannot bind efficiently and without the CAP-cAMP complex, RNA polymerase cannot bind efficiently - Transcription / Translation at the lac operon does not proceed |
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Constitutive Enzymes |
Enzymes that are produced continuously, regardless of the chemical makeup of the environment |
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Inducible Enzymes |
Enzymes that are produced only when specific chemical substrates are present in the environment |
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Negative Control of Gene Expression |
Genetic expression occurs unless it is shut off by some form of a regulator molecule |
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Positive Control of Gene Expression |
Transcription occurs only if a regulator molecule directly stimulates RNA production |
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Cis-Acting Regulatory Regions |
Bind molecules that control transcription of a gene cluster |
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Structural Genes |
Genes encoding for the primary structure of an enzyme |
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lacZ |
Gene in the lac operon that encodes Beta-galactosidase |
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lacY |
Gene in the lac operon that specifies the primary structure of permease |
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Beta-galactosidase |
Enzyme whose primary role is to covert the disaccharide lactose to the monosaccharides glucose and galactose |
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Permease |
Enzyme that facilitates the entry of lactose into the bacterial cell |
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lacA |
Gene in the lac operon that codes for the enzyme transacetylase |
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Transacetylase |
Enzyme that may be involved in the removal of toxic byproducts of lactose digestion from the cell |
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Constitutive Mutations |
- Mutations that allow for the production of lac operon enzymes regardless of the presence or absence of lactose - e.g.) lacI- and lacO^c |
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lacI |
- Repressor gene located upstream from lacZ, lacY, and lacA - Mutation here alters operator-binding region of repressor |
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lacO^c Constitutive Mutation |
- Mutation in region immediately adjacent to the structural genes in the operator region of the operon - Results in alteration in nucleotide sequence of operator gene to stop binding by the repressor - Result is continuous gene expression |
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F' Plasmid |
F plasmid that contains chromosomal genes |
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Merozygote |
A cell that is diploid for certain added genes (but not for the rest of the chromosome) |
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lac Repressor Loop |
- Twist in DNA conformation caused by simultaneous binding by the repressor at two operator sites - All three operators must be bound for maximum repression |
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Attenuator |
- Regulatory region within the leader sequence that may stop transcription or allow it to proceed |
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Anti-terminator Hairpin |
- mRNA secondary structure formed if tryptophan is scarce - Transcription is able to proceed past this region |
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Terminator Hairpin |
- mRNA secondary structure formed in the attenuator region if tryptophan is present - Transcription is stopped prematurely just beyond the attenuator |
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Leader Sequence |
- The region of an mRNA that is directly upstream from the initiation codon - Also called: 5' untranslated region |
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tRNA^Trp |
- Must be produced in order for terminator hairpin to form - Encoded by leader sequence - Tryptophan must be present for its production to take place |
