Gene Regulation

These flashcards cover key concepts in gene regulation, focusing on differences between prokaryotic and eukaryotic systems, mechanisms of transcriptional control, and the roles of various regulatory elements.

What causes different cell types to look and function so differently despite having the same DNA?

Differences in cell or tissue-specific gene regulation lead to varying gene expression.

Define gene regulation in the context of bacterial versus eukaryotic gene regulation.

Bacteria have fewer protein coding genes and one cell type, relying heavily on environmental response, while eukaryotes have many more protein coding genes and hundreds to thousands of cell types with tighter gene expression control.

What type of enzymes do bacteria produce only when specific substrates are present?

Inducible enzymes.

What are constitutive enzymes?

Enzymes that are continuously produced regardless of the environment's chemical makeup.

What is the lac operon and what role does it play in gene regulation?

The lac operon is an inducible operon system that controls the utilization of lactose as an energy source.

What is the function of the repressor protein in the lac operon?

The repressor protein binds to the operator to block transcription of the operon genes.

Explain the role of activator proteins in prokaryotic positive control of transcription.

Activator proteins bind regulatory DNA sequences and facilitate RNA polymerase binding at promoters, initiating transcription.

What are enhancers and how do they regulate gene transcription?

Enhancers are cis-acting sequences that increase transcription rates and can be located far from the promoter.

What is the difference between cis-acting and trans-acting elements in transcription regulation?

Cis-acting elements are located on the same chromosome as the gene they regulate, while trans-acting elements can bind to their target sequences on any chromosome.

Describe the impact of DNA methylation on transcription.

DNA methylation typically inhibits transcription.

What are the mechanisms of epigenetic alterations to the genome?

Methylation, histone modification, and non-coding RNA actions represent major epigenetic mechanisms.

What is the concept of imprinting and how does it affect gene expression?

Imprinting refers to the differential expression of genes based on their parent of origin, where certain genes are transcriptionally inactive depending on whether they are maternally or paternally derived.

What causes Position Effect Variegation (PEV) in eukaryotic genomes?

It is caused by mutations that enhance or restrict the spread of heterochromatin, affecting gene expression.

Define the term 'Chromatin ImmunoPrecipitation'.

It is a method used to identify proteins bound to DNA by chemically cross-linking transcription factors to chromatin and using antibodies for precipitation.

How do histone modifications affect chromatin structure?

Histone modifications such as acetylation, methylation, and phosphorylation alter the accessibility of chromatin, influencing gene expression.

What is the function of insulator sequences in gene regulation?

Insulators protect certain genes from the influence of enhancers, ensuring that only targeted genes are regulated.