5.1.7 Mutations Flashcards
Mutation
A rare, random change in an organism’s sequence of DNA bases that can be inherited
What does mutation cause?
Gene to change which produces a genetic variant- different form of gene
How does mutation cause this?
Sequence of DNA bases in gene codes for order of amino acids/primary structure = codes for different protein
Overall, what effect does mutation have over an organism?
Very little to no effect on phenotype
Changes protein so little(or not at all) so that function is unaffected
What/ how cystic fibrosis?
Caused by deletion of 3 bases which code for protein that controls movement of salt and water in and out of cells.
Protein produced by mutated gene doesn’t work properly=excess mucus production in lungs & digestive system = difficulty to breathe and digest food
What is non-coding DNA?
Sequences of bases in genes which don’t code for proteins
Mutation in coding DNA
Affects protein’s structure & function
Eg active site of enzyme altered so it no longer fits substrate or functions
Mutations in non-coding DNA
Affects how genes are expressed
Eg whether genes are ‘switched on’
Stop transcription of mRNA so protein coded for by gene isn’t produced
What did Mendel do?
Crossed tall pea plant w dwarf pea plant -all offspring were tall Crossed offspring w each other - 25% dwarf, 75% tall Explained by genetic cross diagram Discovered dominant and recessive inherited factors
Why are mutations often harmful?
- can cause cancer (when cells grow and divide uncontrollably)
- cause production of abnormal protein channels (channels which allow molecules to be transported through cell membrane) which don’t function properly
- cause different chapped protein molecules to be made
Mutations can also be…
Neutral and even beneficial (eg. some mutations in bacteria enable them to be resistant to antibiotics, increasing survival)
