Evolution & Genetics
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What is genetic redundancy
It refers to the fact that different codons can code for the same amino acid, as that no codon ever means two different amino acids, only one
What’s variation
The difference of physical characteristics, basic function and behaviour between numbers of a species. The difference that exists between an individual or populations of a species
What’s a mutation
The change in a gene or chromosome leading to new characteristics in an organisation
Types of gene mutations
Deletion Insertion Substitution
Types of chromosomal mutations
Deletion Duplication Inversion Translocation
What things can mutations occur during/due to
• Mutagens (chemicals, viruses, Radiation) • DNA replication (gene mutations) • cell division (chromosome mutations)
What causes variation
Mutation (main cause) Random fertilisation Migration Recombination during meiosis - crossing over - independent assortment - non - disjunction
What’s random fertilisation
When the sperm that fertilised the egg is unknown - therefore the DNA can’t be determined
What’s migration
The movement of people from one area to another with the intention of setting permanently
What’s crossing over
The interchange of the parts of the chromatids of a homologous pair of chromosomes during the first stage of meiosis. Creates a new combination of alleles
What’s independent assortment
The random combination of alleles due to allele pairs separating independently of each other
What’s non-disjunction
When one or more of the chromosome pairs fail to seperate during meiosis
What’s a species
A group of individuals that share many characteristics and are able to interbreed and produce fertile offspring
What’s a population
A group of organisms of the same species living in the same area at the same time
What’s a gene pool
The sum of all alleles in the gene population
What’s evolution
Change in allele frequency within a gene pool from one generation to the next
Things that lead to evolution (mechanisms)
Mutation Gene flow Random Genetic drift Natural selection Isolation
What’s gene flow
The movement of alleles into/out of a population, as a result of immigration/emigration
What’s genetic drift
The variation in the relative frequency of different genotypes, in a small population due to chance events
What are the principles of natural selection
• variation • overproduction • comp for resources & survival of the fittest • high reproductive rate • heritability • change in allele frequency over generations
What’s a selective agent
An environmental factor that kills certain animals
Four factors that induce evolution
1) the potential for predations to increase in numbers 2) genetic variation as a result of mutation and sexual reproduction 3) competition for resources 4) proliferation of individuals with better survival and reproduction
What are the disruptions to genetic equilibrium
Evolution Mutation Gene flow Genetic drift Nonrandom mating Natural selection
What’s a frameshift mutation
When the whole strand of DNA has been altered due to an insertion/deletion of a nucleotide base, affecting the phenotype outcome