Populations and evolution Flashcards
What is the definition of genotype
-genotype is the genetic constitution of an organism
genotypes are the gene
what is the phenotype
phenotype is the expression of this genetic constitution and its interaction with the environment.
phenotype is what we see ( how the genes express)
what are alleles
different versions of the same gene
what is meant by the term dominant
the dominant allele masks the effect of the other
what is meant by the term codominant
both alleles are expressed so the phenotype is a combination of both alleles e.g. red and white alleles making pink phenotype
what is meant by the term recessive
the recessive allele is masked by a dominant one
what is meant by homozygous
both alleles at a specific gene locus are the same. could be homozygous recessive or dominant
what is meant by the term heterozygous
the alleles at a specific gene locus are different
what does monohybrid inheritance mean
the inheritance of a single gene e.g. plant height
what does dihybrid inheritance mean
the inheritance of two separate genes
what is meant by sex linkage
sex linkage is when an allele that codes for a characteristic is found on the sex chromosome. It is therefore inherited with the sex
e.g gene for colour vision, haemophilia
what is meant by autosomal linkage
autosomal linkage is when two genes are found on the same chromosome they are therefore very likely to be inherited together
the closer two genes are, the more likely they are to be inherited together
what is meant by multiple alleles
when there are more than two alleles
e.g. blood group A B O
what is the formula for chi squared
(Observed-Expected)² /Expected
what is meant by epistasis
the interaction of one gene upon another gene
what is a population
group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed
what is a gene pool
number of alleles within in a population
what is the definition of allele frequency
the likelyhood of one allele being at a specific gene locus
what is a species
a group of organisms that breed to make fertile offspring
what is the hardy-weinberg equation
p² + 2pq + q²=1
p+q=1
p= the allele frequency of the dominant allele q= the allele frequency of the recessive allele p²= frequency of the homozygous dominant genotype q²= frequency of the homozygous recessive genotype 2pq= the frequency of heterozygous genotype
what assumptions/ conditions does the population have to fulfil to be a Hardy weinberg population
no selection based on trait. e.g eye colour
no mutation
large population
What is sympatric speciation
e.g. disruptive natural selection
- reproductive isolation within the same habitat
- mutation can cause genetic differences this is called DISRUPTIVE natural selection
- thus changes allele frequency and different alleles passed on
- this results in 2 separate species
- these different species can no longer interbreed
What is Allopatric speciation
- where 2 populations become geographically isolated
- this prevents interbreeding
- environmental conditions in either side may change
- this causes natural selection and adaptions to new environment take place
- populations become different from one another to the point where they can no longer interbreed and become new species
