UNIT 1 - THE EVOLUTION OF LIFE_BIOLOGY IB

Evolution

Heritable

transmissible from parent to offspring

Evolution

the cumulative change in the characteristics of a population

Base pairs

a unit of DNA or RNA made of two chemical bases joined together by hydrogen bonds

Base sequence

the exact order of nitrogen-containing chemical blocks, called nucleotide bases, along a strand of DNA or RNA

Selective breeding

the process where humans choose specific plants or animals to mate

Natural selection

the process where plants and animals with traits best suited to their environment survive and have more babies

Alleles

a different form of a gene

Convergent evolution

different origin, same function

Analogous structure

similar structure, different origin

Homologous (chromosomes and structures)

matching pairs of chromosomes that share the same length, shape, centromere position, and gene order

Non-homologous

the primary cellular pathway that repairs double-strand breaks in DNA by directly sticking the broken ends back together without needing a matching sequence template

Speciation

the evolutionary process where new and distinct species form from a single ancestral population

Sympatric

two populations of a species in the same location, can’t interbreed; genetic change

Allopatric

two populations of a species before geographically separated; rivers or mountains

Adaptive radiation

an evolutionary process where a single ancestral species rapidly diversifies into many new forms

Interspecific

between different species

Intraspecific

within or between members of the same species

Polyploidy

more than two sets of homologous chromosomes

Hybridization

the mixing of atomic orbitals (such as s, p, and d) to form new, identical hybrid orbitals

Variation

a change different to the original

Mutation

a change in the base sequence

Abiotic

non-living

Biotic

living

Gene pool

the total collection of all genes, including all different gene forms, or alleles, in a single interbreeding population

Population

A group of individuals of the same species living in the same geographic area at the same time and capable of interbreeding.

Biological species

A group of organisms that can interbreed in nature and produce fertile offspring, while being reproductively isolated from other such groups.

Horizontal gene transfer

The movement of genetic material between organisms other than through vertical transmission from parent to offspring.

Sexual dimorphism

The systematic physical differences in size, appearance, or structure between males and females of the same species.

Ring species

A connected series of neighboring populations, each of which can interbreed with adjacent populations, but for which there exist two "end" populations in the series that are too distantly related to interbreed.

Gene pool

he total collection of all genes, including all different gene forms, or alleles, in a single interbreeding population

Genetic drift

an evolutionary mechanism where allele frequencies in a population change over generations due to random chance instead of natural selection

Allele frequency

how often a specific gene variant appears in a group of individuals

Directional

a type of natural selection where an extreme phenotype is favored over all other phenotypes

Disruptive

a type of natural selection where extreme values for a trait are favored over intermediate values

Stabilizing

a type of natural selection where average traits are favored and extreme variations are rejected

Hardy-Weinberg

states that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences

Binomial

the official system of naming living things

Karyotype

a complete set of chromosomes in an organism

Genome

the complete set of DNA instructions found in a living organism

Proteome

the entire set of proteins expressed by a genome, cell, tissue, or organism at a given time and under defined conditions

Clades

a group of living things that includes one single common ancestor and all of its descendants