9 genetic diversity and adaptation Flashcards
what is a single point mutation?
random and spontaneous change to a single base in a gene
what are some consequences of a gene/single point mutation?
- change to primary structure (sequence of amino acids)
- change to secondary structure (position of weak H bonds)
- change to tertiary structure (^change active site of enzymes)
when do gene mutations occur?
DNA replication
what are three gene mutations?
substitution
addition
deletion
why do some substitution mutations lead to silent mutations?
because the code is degenerate
what happens if a mutation occurs in the stop codon?
premature termination- will not be able to perform its function
what do addition and deletion mutations lead to?
frame shift mutations
where would a frame shift mutation have a lesser effect- at the start or end of a sequence?
end
mutations in gametes are often…
fatal
what do mutagenic agents do?
increase the rate of spontaneous mutations
name 3 mutagenic agents
- high energy ionising radiation (X rays)
- DNA reactive chemicals (benzene)
- biological agents (virus)
what is chromosomal non-disjunction?
when a pair of homologous chromosomes fail to separate during metaphase
what are the types of chromosomal mutation?
duplication
inversion
translocation
what is a duplication mutation?
a doubling of part of a chromosome
what is an inversion mutation?
when a segment of bases are reversed
hat is a translocation mutation?
when groups of base pairs relocate usually between non homologous chromosomes
define allele
different version of same gene
define genetic diversity
the number of different alleles of genes in a population
any mutation could provide a:
- selective advantage
- neutral
- selective disadvantage
what is selection pressure?
a change that causes a certain characteristic to be favoured
explain natural selection
- better adapted individuals more likely to survive and reproduce to pass on their alleles
- less well adapted individuals fail to survive and reproduce to pass on their alleles
- organisms subjected to selection pressure
what is a biotic factor?
living
what is an abiotic factor?
non living
give an example of a biotic factor
- predators
- virus/bacteria
- presence of mates
