Topic 10

Operon

A group of genes in prokaryotes that are transcribed together under the control of a single promoter.

Promoter

The DNA sequence where RNA polymerase binds to initiate transcription.

Operator

A regulatory DNA sequence that controls the expression of the operon by binding regulatory proteins.

Regulatory Genes

Genes that control the expression of other genes by producing regulatory proteins or RNAs.

Regulatory Proteins

Proteins produced by regulatory genes that can activate or inhibit gene expression.

Cis-acting Elements

any sequence of DNA that is not converted into other form but functions as it is in situ, affecting only the DNA to which it is physically linked

Trans-acting Factors

the product of a DNA which may be a protein or an RNA — the product dffuses away from its site of synthesis and works elsewhere

Negative Control

Regulation of gene expression where a repressor inhibits transcription.

Positive Control

Regulation of gene expression where an activator enhances transcription.

Inducible Operon

An operon that is normally off but can be turned on by an inducer.

Repressible Operon

An operon that is normally on but can be turned off by a repressor.

Lac Operon

An operon involved in lactose metabolism in E. coli.

Allolactose

The inducer that allows the lac operon to be expressed by inactivating the repressor.

cAMP

Cyclic adenosine monophosphate; a molecule that enhances the transcription of the lac operon when glucose levels are low.

CAP (catabolite activator protein)

A protein that activates transcription of the lac operon in the presence of cAMP and low glucose.

Tryptophan Operon

An operon that is involved in the biosynthesis of tryptophan in bacteria.

Attenuation

A regulatory mechanism that leads to premature termination of transcription based on the availability of aminoacyl-tRNA.

Structural Genes

Genes that encode for proteins that have a direct effect on cell structure or function.

Constitutive Expression

Continual expression of a gene, regardless of environmental conditions.

Mutational Studies

Experiments that involve creating mutations to study gene function and regulation mechanisms.

Partial Diploid Studies

Research involving organisms with extra genetic material to understand regulation of operons.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by its genotype.

Intra-cellular stimuli

Signals from within the cell that influence gene expression.

Extra-cellular stimuli

Signals from outside the cell that influence gene expression.

Dynamic Regulation

The ability of cells to rapidly alter gene expression in response to environmental changes.

Repressor (lacI)

A protein that binds to the operator of the lac operon, blocking transcription in the absence of lactose.

Lactose Metabolism

The process by which cells break down lactose into glucose and galactose.

Gene Expression

The process by which information from a gene is used to synthesize a functional gene product, like a protein.

Transcription

The process of copying a segment of DNA into RNA.

RNA polymerase

The enzyme responsible for synthesizing RNA from a DNA template.

Operator Binding

The process by which a regulatory protein interacts with the operator to control operon expression.

Metabolic Preference

The tendency of an organism to utilize certain substrates preferentially, such as glucose over lactose in E. coli.

Poly-cistronic mRNA

a single mRNA molecule that encodes multiple proteins — this type of mRNA is common in prokaryotes, where it enables the coordinated expressionf of genes that are part of the same pathway or function

Secondary Structure

The localized folding of the RNA molecule that can influence its function, such as in attenuation.

Phenotypic Differences

Observable variations in traits among individuals due to different patterns of gene expression.

Signal Molecules

Small molecules that facilitate communication and regulatory processes within and between cells.

Environmental Responses

Changes in gene expression as a reaction to external conditions.

E. coli

A common bacterium used as a model organism in molecular genetics.

Regulatory Elements

Sequences in the DNA that play a role in regulating the expression of nearby genes.

Allosteric Regulation

The process by which the binding of a molecule affects the activity of a protein, such as a repressor or activator.

RNA Stability

The lifespan of an RNA molecule in a cell, which can affect levels of gene expression.

Signal Transduction

The process by which a signal is transmitted through the cell as a series of molecular events.

Feedback Mechanisms

Processes that regulate gene expression rates based on the levels of gene products.

Transcription Termination

The process of stopping the transcription of RNA from DNA.

Gene Regulation

The process of turning genes on or off, controlling the timing and amount of gene expression.

Bacterial Genetics

The study of genes and inheritance in bacteria, including operon functionality.

Cellular Mechanisms

Biological processes and structures that govern cellular activities including regulation of gene expression.

Mutation Impact

The effects that changes in the DNA sequence may have on gene function and regulation.

Experimental Application

Utilizing knowledge of prokaryotic regulation for practical experiments.

Genomic Similarity

The degree of genetic similarity between different organisms, leading to diverse phenotypes.

short-term molecules

Proteins and mRNA are quickly produced and degraded as needed, allowing prokaryotes to rapidly respond to environmental changes, such as shifts in nutrient availability, temperature, or the presence of toxins.

What is the regulatory gene in lactose utilization for E. coli

lac I

What are the three strcutural genes in lac I

lac Z, lac Y, lac A

What does lac Z encode for

beta galactosidase

What does lac Y encode for

lac permease

What does lac A encode for

transacetylase