Bio SAC 5

population

a group of individuals of the same species occupying a particular area at the same time

species

a group of similar organisms that are able to interbreed and produce fertile and viable offspring

mutation

a permanent change in the DNA base sequence

genotype

the genetic make up or the combination of alleles for a particular gene of an organism

phenotype

a physical characteristic determined by genotype and environment

evolution

a change in allele frequencies of a population over time

gene pool

the sum total of alleles present in a population of organisms

what causes alleles frequencies to change

gene flow, genetic drift, selection pressures, mutations

what are the types of mutation

point, frameshift, block (chromosomal)

point mutation

the substitution of a single nucleotide which may alter the phenotype

silent mutation

no change to the amino acid due to degenerate genetic code

missense mutation

a new amino acid is coded for

nonsense mutation

a stop codon is coded for and a shorter polypeptide is produced

frameshift mutation

the insertion or deletion of a nucleotide that causes the DNA to be read in a differ

block mutation

large section of DNA is altered, can result in duplication, deletion, inversion,

aneuploidy

an abnormal number of chromosomes in a karyotype

natural selection

an evolutionary process where individuals that are best suited to the environment survive, reproduce and pass on their genetic information to the next generation

natural selection acronym

VSSSRAG

VSSSRAG

variation, selection pressure, selection advantage, survive, reproduce, allele frequencies, generations

gene flow

the movement of alleles between interbreeding populations can introduce alleles into a population, increasing genetic diversity

immigration

movement of alleles into a population

emigration

movement of alleles out of a population

genetic drift

the change in a gene pool as a result of random or chance events

founder effect

a small group of non-representative individuals leave the population and set up their own population in a new territory

bottleneck effect

a severe reduction in the number of organisms in a population and so genetic variation is significantly reduced

selective breeding

a process whereby humans select which organisms reproduce to increase/improve a particular trait

fossil

a fossil is the preserved remains of an organism or a direct evidence of its presence

the fossil record

a record of organisms that once lived, through geological time as documented by fossils

impression fossil

the entire organism decays but the shape or impression is left behind in the rock

body fossil

part of the organism itself that have been mineralised

trace fossil

preserved evidence of the animal’s activity

mummified fossil

animals that are trapped in a substance that reduce decay

conditions for fossilisation

1. rapid burial

2. decomposition is prevented

3. organism lies undisturbed

extinction

permanent loss of a species

index fossil

a fossil that can be used to date other fossils found in same rock later

transitional fossil

intermediate forms that provide an evolutionary link between two different species

relative dating

comparing a fossil’s position to other fossils or rock in surrounding strata

absolute dating

provides an exact numerical age of a fossil sample or rock strata

half life of carbon 14

5730 years

speciation

the process by which new species are formed from a pre existing ancestral species

allopatric speciation

characterised by geographical isolation

sympatric speciation

characterised by no geographical isolation

structural morphology

study of an organism’s structure to establish relatedness

homologous structures

a physical structure within a group of species that performs a different function yet has the same underlying basic structure

vestigial structures

a structure that is no longer functional but served a purpose in a common ancestor

molecular homology

analysis of DNA and amino acid sequences as evidence of evolutionary relationships

gene conservation

genes which remain largely unchanged throughout evolution, codes for an important protein which plays a significant role in organisms

molecular clock

technique used by researchers to determine when two species have diverged

phylogenetic trees

branching diagrams that depict evolutionary relationships between organisms