Bio Keystones (copy 47-72)

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Endosymbiosis

A theorized process in which early eukaryotic cells were formed from simpler prokaryotes.

Energy Pyramid

A model that illustrates the biomass productivity at multiple trophic levels in a given ecosystem.

Energy Transformation

A process in which energy changes from one form to another form while some of the energy is lost to the environment.

Environment

The total surroundings of an organism or a group of organisms.

Enzyme

A protein that increases the rate of a chemical reaction without being changed by the reaction; an organic catalyst.

Eukaryote

A type of organism composed of one or more cells containing a membrane‐bound nucleus, specialized organelles in the cytoplasm, and a mitotic nuclear division cycle.

Evolution

A process in which new species develop from preexisting species (biological evolution or macroevolution); a change in the allele frequencies of a population of organisms from generation to generation (genetic evolution or microevolution).

Exocytosis

A process in which a cell releases substances to the extracellular environment by fusing a vesicular membrane with the plasma membrane, separating the membrane at the point of fusion and allowing the substance to be released.

Extinction

A term that typically describes a species that no longer has any known living individuals.

Extracellular

Located outside a cell.

Facilitated Diffusion

A process in which substances are transported across a plasma membrane with the concentration gradient with the aid of carrier (transport) proteins; does not require the use of energy.

Food Chain

A simplified path illustrating the passing of potential chemical energy (food) from one organism to another organism.

Food Web

A complex arrangement of interrelated food chains illustrating the flow of energy between interdependent organisms.

Forensics

The science of tests and techniques used during the investigation of crimes.

Fossils

The preserved remains or traces of organisms that once lived on Earth.

Founder Effect

A decrease in genetic variation caused by the formation of a new population by a small number of individuals from a larger population.

Frame‐shift Mutation

The addition (insertion mutation) or removal (deletion mutation) of one or more nucleotides that is not indivisible by three, therefore resulting in a completely different amino acid sequence than would be normal. The earlier in the sequence nucleotides are added or removed, the more altered the protein will be.

Freezing Point

The temperature at which a liquid changes state to a solid.

Gamete

A specialized cell (egg or sperm) used in sexual reproduction containing half the normal number of chromosomes of a somatic cell.

Gene

A sequence of nucleotides composing a segment of DNA that provides a blueprint for a specific hereditary trait.

Gene Expression

The process in which a nucleotide sequence of a gene is used to make a functional product such as protein or RNA.

Gene Recombination

A natural process in which a nucleic acid molecule (usually DNA but can be RNA) is broken and then joined to a different molecule; a result of crossing‐over.

Gene Splicing

A type of gene recombination in which the DNA is intentionally broken and recombined using laboratory techniques.

Gene Therapy

The intentional insertion, alteration, or deletion of genes within an individual's cells and tissues for the purpose of treating a disease.

Genetic Drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.