bio

Feedback inhibition

When a product that the cell is making stops the production of said product.

Operon

A DNA sequence that consists of a promoter, operator, and genes involved.

Genome

The entire set of genetic information in an organism.

Operator

The region responsible for keeping the gene on or off for gene expression.

Promoter

A sequence where RNA polymerase binds to initiate gene expression.

Tryptophan operon activity

It is turned off in the presence of tryptophan and on in its absence.

Repressor in presence of tryptophan

Changes shape to bind to the operator and prevent gene expression.

Allolactose

The signaling molecule that binds to the repressor to remove it from the operator.

cAMP role

A signaling molecule that enhances RNA polymerase activity.

CRP (Cyclic AMP receptor protein)

A protein activated when lactose levels are high and glucose levels are low.

Acetylation

A chromatin modification that unwinds DNA to allow gene expression.

Methylation

A chromatin modification that compacts DNA to prevent gene expression.

RNA splicing

The process that removes introns and joins exons in mRNA.

Introns

Sections of mRNA that are removed and not expressed.

Exons

Sections of mRNA that remain and are expressed.

Ubiquitin

A molecule that triggers the degradation of proteins.

Descent with modification

The idea that species change over time and share a common ancestor.

Paleontology

The study of fossils and how they support evolutionary theory.

Strata

Layers of sedimentary rock that contain fossils.

Homology

Similarity between species resulting from common ancestry.

Analogous features

Similar structures in different species that serve similar functions but do not share a common ancestor.

Microevolution

Changes in allele frequency in a population over time.

Gene Pool

The total collection of alleles in a population.

Genetic drift

Random fluctuations of allele frequencies from one generation to the next.

Gene flow

The movement of alleles among populations due to migration.

Adaptive evolution

An increase in allele frequency that enhances fitness.

Directional selection

Natural selection favoring individuals at one end of the phenotypic range.

Stabilizing selection

Natural selection favoring moderate/average phenotypes.

Heterozygote advantage

Higher fitness of heterozygotes compared to either homozygous form.