Genes

Genetic Regulation

The control of gene activity, determining whether genes are turned on or off, and how much product they produce.

Messenger RNA (mRNA)

The transcribed form of genes that is translated into proteins.

Prokaryotic organisms

Organisms with simple cells lacking a nucleus, such as E. coli.

Eukaryotic organisms

Complex organisms, including human cells, that have a nucleus.

Gene expression

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

Chromatin

The complex of DNA and proteins, specifically histones, that make up chromosomes.

Euchromatin

Regions of DNA that are actively expressed and associated with gene transcription.

Heterochromatin

Regions of DNA that are densely packed and not actively expressed.

Exons

Coding segments of DNA that are transcribed into mRNA and translated into proteins.

Introns

Non-coding segments of DNA that are transcribed but not translated and are removed during RNA processing.

Operon

A cluster of genes under the control of a single promoter, common in prokaryotic gene regulation.

Repressor

A regulatory protein that binds to an operator to prevent transcription and turn off gene expression.

Activator

A protein that binds to a specific region of DNA to increase gene transcription.

Feedback inhibition

A regulatory mechanism in which the end product of a reaction inhibits its own production.

Repressible operon

An operon that is typically on but can be turned off when a specific product is abundant.

Inducible operon

An operon that is typically off but can be turned on in the presence of an inducer.

BRCA gene

A gene associated with increased risk of breast cancer; not all carriers develop cancer.

Oncogenes

Genes that have the potential to cause cancer when mutated or aberrantly expressed.

Carcinogens

Substances that promote cancer development, increasing the likelihood of mutation.

Poly A tail

A stretch of adenine nucleotides added to the 3' end of mRNA to enhance stability.

RNA splicing

The process of removing introns and joining exons in a pre-mRNA transcript.

RNA modifications

Changes made to RNA, such as capping and polyadenylation, which are crucial for stability and translation.

Histone acetylation

The addition of acetyl groups to histones, leading to a relaxed chromatin structure and enhanced gene expression.

DNA methylation

The addition of methyl groups to DNA, often leading to gene silencing.

Cell cycle checkpoints

Control mechanisms in the cell cycle that ensure proper cell division.

Energy efficiency in bacteria

The ability of bacteria to conserve energy by only expressing necessary genes.

Natural selection in bacteria

The process by which less useful genes are eliminated over time for resource conservation.

Gene expression regulation in eukaryotes

A complex process that involves multiple levels of control beyond simple operon systems.

mRNA degradation

The process of breaking down mRNA to regulate protein production and maintain cellular function.

Cancer risk evaluation

Assessing factors like smoking, diet, and family history to determine an individual's risk of developing cancer.

Chromatin structure impact

How the arrangement of chromatin can influence the expression of genes.

Proportion of expressed DNA

In bacteria, nearly 100% of their DNA is expressed, whereas in humans, only about 2% is actively expressed.

Gene possession vs. expression

Having a gene does not guarantee its activity; many factors influence whether a gene is expressed.