Variation & Mutations Flashcards
What is a “species”?
A group of individuals that are able to breed and produce fertile offspring.
What is a “population”?
A group of organisms of a particular species living in the same place at the same time.
What is an allele?
Alternative form of a gene.
What is the gene pool?
Sum of all alleles in a given population.
What is allele frequency?
How often a particular allele for a gene appears in a given population.
What is a genotype?
The genetic constitution of an individual organism
What is a phenotype?
The observable characteristics of an organism resulting from the interaction of the genotype with the environment.
What is a mutation?
A spontaneous change in a gene or chromosome leading to new characteristics in an organism.
What is a gene mutation?
A change in a single gene.
What is a chromosomal mutation?
All or part of a chromosome is affected.
What is an induced mutation?
A mutation caused by a mutagenic agent.
What is a mutagenic agent? Give 3 examples.
An environmental agent that increases the rate of mutation.
Formaldehyde, ionising radiation, mustard gas.
What are spontaneous mutations?
Mutations caused by an error in natural biological processes (e.g. non-disjunction in anaphase)
What are somatic mutations?
Mutations occurring in body cells.
Individual is affected, offspring will not be affected.
What are the 2 classifications of mutations by amount of gene affected?
Gene mutations
Chromosomal mutations
What are the 2 classifications of mutations by cause?
Spontaneous mutation
Induced mutation
What are the 2 classifications of mutations by cell type affected?
Somatic and germ-line
What are germ-line mutations?
Mutations occurring in gametes/sex cells.
Individual can be unaffected.
Mutation will be passed on to offspring.
What are the 4 classifications of mutations by effect?
Missense
Nonsense
Neutral
Silent
What are missense mutations?
Mutations which cause a change in the amino acid, and therefore the protein produced.
What are nonsense mutations?
Mutations which change the base code to “STOP”.
Synthesis of the protein stops, the shorter protein produced may unable to carry out its function.
What are neutral mutations?
Mutations which cause a change in an amino acid.
Codon is changed, but is still coded for the same amino acid.
What are silent mutations?
Mutations which cause no change in the amino acid.
What are the 3 types of point mutations? Provide a brief explanation.
Insertion - new nucleotide is added
Substitution - existing nucleotide is replaced by one with a different base
Deletion - nucleotide is removed
What is a frameshift?
A process which occurs when bases have been added or removed, resulting in the codon starting at a different base.
What are 5 sources of variation?
1) Crossing over
2) Independent assortment
3) Non-disjunction
4) Random fertilisation
5) Mutations
What is trisomy 13? What are the symptoms?
Patau syndrome.
Intellectual disability, microcephaly (small head), extra fingers, cleft palate.
More than 80% die within first month of life.
What is monosomy X? What are the symptoms?
Turner syndome.
Short stature, infertility, lack of sexual characteristics
What are the 5 main ways that the frequency of alleles in the gene pool change?
1) Genetic drift/founder effect
2) Mutations
3) Natural selection
4) Migration
5) Barriers to gene flow
What is random genetic drift?
When the frequency of an allele within a population changes due to chance rather than natural selection.
More prevalent in small populations, as a higher proportion of the population will express the change.
