5.1 variation / mutatiom Flashcards
environmental variation
piercings, glasses, tatoos
genetic variation
eye colour, blood group, prescence of genetic disorders
how many genes control a genetic disorder
one
continuous data
a characteritic can be any value between a min-max
e.g. height
- range of values
genetic or environmental
multiple genes
discontinuous data
distinct groups of characteristics eg blood type - A, B, AB, O
- one (or few) genes
genetic only
why is variation essential for survival
cruical to evolution - each species in a stable environment is there because it has adapted to be there
genetic vaariation is the result of
- mutations
- sexual reproduction (2random gametes fuse)
- meiosis (all gametes genetically diff - random pairing + switching of genes)
what is a mutation
- change in the sequence of bases in DNA
- occur randomly
- can occur if DNA isnt replicated correctly
- some substances eg ethanol + ionising radiation increase chance of mutation
lead to ALLELES
mutation effects
harmful - affect person/offspring eg cancer
neutral - dont benefit nor harm eg attached earlobes
beneficial - eg tall neck for giraffes
substitution mutations
- silent - results in triplet code that codes for same amino acid
- nonsense - results in a stop - shorter protein made
- missense - diff amino acid coded for - diff shape if enzyme diff active site
types of mutation
- substitution - one base changed to another
- insertion- base added - to gene
- deletion - base deleted - alters all triplet code downstream
non coding sections of DNA
- specific sequences of dna before a gene which trigger transcription
- if mutation occurs here - transcription factors cant bind - gene not turned on - gene not transcriped - proteins not produced
