Gene Regulation (Lac & Trp)
How many sites does the lac operon have where a lac repressor can bind?
3
In the trpL mRNA, how many stem loops are possible?
3
Regulatory protein that increases the RATE of transcription
Activator
cyclic AMP (cAMP) is a small effector molecule produced by the enzyme
Adenylyl cyclase
A conformational change that prevents the lac repressor from binding to the lac operator occurs when ___ binds to the lac repressor
Allolactose
The intracellular concentration of the inducer ___ remains high as long as lactose is AVAILABLE in the environment
Allolactose
By studying the lack of transcription of the trp operon in the absence of a trp repressor, Charles Yanofsky discovered
Attenuation
The somewhat imprecise term that describes how transcriptional regulation is influenced by glucose is called:
Catabolite repression
A DNA segment that must be adjacent to the genes it regulates is called a
Cis-acting element
Unregulated genes are also called...
Constitutive genes
The sequential use of sugars by a bacterial cell is called
Diauxic growth
The genes in the trp operon encode
Enzymes used in tryptophan biosynthesis
Phenomenon in which the LEVEL of gene expression can VARY under different conditions:
Gene Regulation
A strain of bacteria containing F' factor genes is called a ___ or a partial diploid
Merozygote
A protein such as a represor that inhibits transcription is exerting....
Negative control of transcription
Group of two or more genes under the transcriptional control of a single promoter
Operon
Transcription regulation by an activator protein is considered to be...
Positive control
The control of proteins already present in the cell
Posttranslational regulation
Regulatory protein that binds to DNA and inhibits transcription
Repressor
In attenuation, transcription is
Stopped prematurely
In the trpL sequence, the 3-4 stem-loop together with the U-rich attenuator sequence acts as a
Terminator sequence
How does an effector molecule influence gene expression?
The effector molecule binds to a regulatory protein and affects its ability to bind to DNA
What type of regulatory element does not need to be adjacent to the gene(s) its regulating?
Trans-acting factor
In bacteria, the most common way to regulate gene expression is by influencing the rate of
Transcription initiation
What proteins do lacZ, lacY & lacA genes encode for?
lacZ - Beta-galactosidase: enzyme that cleaves lactose into galactose and glucose lacY - lactose permease: membrane protein required for the active transport of lactose into the cytoplasm of a bacterium lacA - galactoside transacetylase: enzyme that covalently modified lactose
What are the 3 protein-encoding genes in the lac operon?
lacZ, lacY & lacA
An operon encodes for a ___ mRNA, an RNA that contains sequences of TWO OR MORE GENES
polysistronic mRNA poly (many) sistronic (genes)
Genes in the trp operon:
trpE, trpD, trpC, trpB & trpA
The mRNA made from the ___ gene contains codons for 14 amino acids that form the trp leader peptide
trpL