Mutations

evolution

change in characteristics over a number of generations

phenotype

observable characteristic due to genotype

genotype

combination of alleles for a gene

population

group of organisms of the same species living together in a particular place at particular time

geneticists

scientists who specialise in study of inheritance

gene pool

sum of all alleles in a given population

allele frequency

how often each allele of a gene occurs in a population

mutation

change in gene or chromosome leading to new characteristics

gene mutations

changes in a single gene so that the traits normally produced by that gene are changed/destroyed

chromosomal mutations

all/part of a chromosome is affected

mutagenic agents

environmental agent that increases the rate of mutation

examples of mutagens

ultraviolet light, xrays, cosmic rays, radiation

induced mutations

mutation caused by a mutagen

spontaneous mutations

mutation that occurs due to an error in a natural biological process

somatic mutation

change occurring in a gene is a body cell

germinal mutations

change in the hereditary material in the egg or sperm that becomes incorporated into the DNA of every cell in the body of the offspring

phenylketonuria (PKU)

inherited disease resulting in damage to the growing brain (intellectual disability) epileptic seizures and failure to produce pigmentation

missnse mutations

cause change in amino acid

nonsense mutations

change base sequence to stop so shorter protein is produced and unable to function

neutral mutations

cause change in amino acid however amino acid is same type and doesn’t change protein enough to change function

silent mutations

no change to amino acid

point mutations

change in just one of the bases in a DNA molecule

what can point mutation be due to?

• new nucleotide INSERTED to DNA strand

• an existing nucleotide is SUBSTITUTED with another one with a different base

• a nucleotide is DELETED from DNA stran

frame shift

mutation involving an insertion/deletion of one base that results in a change in the way that sequence is read

what can mutations that affect larger sections of DNA be due to?

• duplication

• inversion

• translocation

• non-disjunction

duplication

section of chromosome occurs twice

inversion

breaks occur in a chromosome and the broken piece joins back in but wrong way around

translocation

part of chromosome breaks off and is rejoined to wrong chromosome

non disjunction

during meiosis chromosome doesn’t separate so one daughter cell has extra chromosome and one has less