Natural Selection (long version)

Evolution

Change in the genetic makeup of a population over generations

Population

A group of organisms of the same species in one area

Allelic frequency

The proportion of a specific allele in a population

Gene pool

All the alleles in a population

How to find allelic frequency

Number of a specific allele divided by total number of alleles

Fitness

How well an organism survives and reproduces

Overproduction

More offspring are produced than can survive

Variation

Differences within a population

Natural selection

Individuals with helpful traits survive and reproduce more

Artificial selection

Humans choose which traits get passed on

Darwin

Scientist who helped explain natural selection

Malthus

Influenced Darwin with ideas about population growth and competition

Adaptation

A trait that helps survival and reproduction

Descent with modification

Over generations, populations change

Four principles of natural selection

Variation, overproduction, adaptation, descent with modification

Directional selection

Favors one extreme phenotype

Stabilizing selection

Favors the average phenotype

Disruptive selection

Favors both extreme phenotypes

Normal distribution

Bell curve showing how traits are spread in a population

Speciation

Formation of new species

Geographic isolation

Populations become separated by location

Reproductive isolation

Populations can no longer interbreed in nature

Phylogenetic tree

Diagram showing evolutionary relationships

Classification

Organizing organisms by shared characteristics

Taxonomy

Science of naming and classifying organisms

Taxon

A classification group

Binomial nomenclature

Two-part scientific name

Genus

First part of a scientific name

Species

Second part of a scientific name

Eight levels of classification

Domain, kingdom, phylum, class, order, family, genus, species

Modern classification

Uses phylogeny and genetic similarities

Phylogeny

Evolutionary history of a group of species

Cladistics

Classification based on evolutionary relationships

Three domains

Bacteria, Archaea, Eukarya

Six kingdoms

Bacteria, Archaea, Protista, Fungi, Plantae, Animalia

Virus

Infectious obligate intracellular parasite

DNA virus

Virus with DNA as genetic material

RNA virus

Virus with RNA as genetic material

Capsid

Protein shell of a virus

Lipid envelope

Outer membrane on some viruses

Bacteriophage

Virus that infects bacteria

Attachment

Virus binds to host cell

Entry

Virus enters host cell

Replication and gene expression

Virus makes copies of itself and viral proteins

Assembly

New virus parts are put together

Release

New viruses leave the host cell

Cytopathic effects

Damage caused to infected cells

Vaccines

Weakened pathogens or fragments that train the immune system

Obligate anaerobes

Prokaryotes poisoned by oxygen

Obligate aerobes

Prokaryotes that need oxygen

Facultative anaerobes

Can live with or without oxygen

Bacilli

Rod-shaped bacteria

Spirilla

Spiral-shaped bacteria

Cocci

Spherical bacteria

Staph

Bacterial arrangement in clusters

Strep

Bacterial arrangement in chains

Plasmid

Small circular DNA in prokaryotes

Binary fission

Asexual reproduction in prokaryotes

Conjugation

Gene exchange between prokaryotes

Invading tissues

One way bacteria cause disease

Making toxins

One way bacteria cause disease

Antibiotics

Drugs that kill or stop bacteria

Antibiotic resistance

Ability of bacteria to survive antibiotic treatmen