19. Variation and population

Created by

Mabel smith

Cards (27)

What is variation
Differences in phenotype that exist
What is interspecific variation
Occurs between different species
What is intraspecific variation
Between the same species
How do genetic cause variation
Meiosis
mutations
random fusion of gametes
Which is the only way asexual organisms can have variation
Mutations
What is phenotype  
The expression of the genotype and the environment
How does meiosis cause variation
Independent segregation
crossing over
What is random fertislisation of gametes  
Which gamete fuses with which at fertilisation is a random process and produces new combinations of alleles
What is a mutation
A change in the amount or sequence of amino acids
What can increase chances of mutations
High energy ionising radiation
chemicals like nitrogen dioxide
What are addition and deletion mutations  
When a base is added or deleted
changes all the triplets so causes a frame shift
What is substitution  
One base is swapped for another
What are the 3 consequences of substitution
Mis sense - protein will change
nonsense - stop codon
silent - no change
What is duplication  
When one or more bases are repeated - produces a frame shift to the right
What is inversion
When a group of bases become separated and rejoin in the reverse order
What is translocation of bases  
A group of bases becomes separated from the DNA sequence on one chromosome and becomes inserted into another DNA sequence- often leads to an abnormal phenotype
What is a population
Group of organisms of one species in a habitat
What is a gene pool  
Sum of total of all the alleles of all the gene loci in a population at a particular time
What is the hardy Weinberg equation
P2 + 2pq + q2 = 1
What do the letters in the hardy Weinberg equation mean
p = dominant allele
q = recessive allele
p2 = homozygous dominant
q2 = homozygous recessive
2pq = heterozygous
What does the hardy Weinberg equation state
Frequencies of alleles of a particular gene stay constant from generation to generation
Under what conditions will the hardy Weinberg equation occur
Population must be large
no mutations
no immigration or emigration
random mutation
If a population deviates from the hardyweinberg equation what does it show
That the species are in a constant state of evolutionary flux
What is genetic drift  
Allele frequency can change due to chance
What are two types of genetic variation
Founder effect
genetic bottlenecks
What is the founder effect  
When some organisms become isolated
What is genetic bottlenecks
When a population is reduced to a very small number and there is a reduction in genetic diversity