Genetic Variation and Change

NCEA Level 2 Biology

Heredity

Passing of characteristics from an individual to its offspring.

Gene

Basic unit of heredity. The length of DNA which codes for a protein that determines a specific characteristics.

Allele

Alternative version of gene

Mutation

Permanent change in genetic material. Creates new alleles.

Variation

result of new alleles

Genotype

Genetic information of an individual for a particular characteristic.

Phenotype

Physical expression of genotype (also affected by environment)

Gene pool

all alleles present in population

Allele frequency

Refers to relative frequency of an allele in a population.

Genetic diversity

Refers to variation in amount of genetic information within and among individuals of population/species.

Mutagens

Physical agents that increase rate of mutations

Speciation

Formation of new species

Species

Group of similar looking individuals that can interbreed and produce fertile offspring.

Deme

Local unit of population of any one species.

Haploid

Having single, unpaired chromosome (X)

Diploid

Having two full sets of chromosomes (XX)

Linked genes

Reduce variation in gene pool because reduces mixing of alleles due to them tending to be inherited as a single unit during meiosis.

Recombination

Process where pieces of DNA are broken and combined to make new allele combinations. Increase variation in gene pool because of crossing over when DNA is combined.

Genetic change

Refers to change in frequency of alleles in gene pool.

Natural selection

Process where beneficial alleles help organism survive and pass on alleles, increasing that allele’s frequency.

Evolution

Process by which populations change.

Selecting agents

Environmental factors (biotic and abiotic).

Biotic environment factor

Any living component, organism, or interaction that shapes and affects ecosystem and other living things.

Abiotic environment factor

Non-living physical or chemical part of an ecosystem that shapes and affects living organisms.

Sexual selection

Process where traits that increase chance of mating become more common.

Artificial selection/selective breeding

Where people select individuals to breed.

Inbreeding

Breeding together of closely related individuals.

Gene mutation

occur within a gene and change the base sequence of DNA.

Chromosomal mutation

Cause changes to whole genes/chromosomes.