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