Populations

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  • Created by: Hindleyc
  • Created on: 31-03-19 11:20
What do species exist as?
1 or more populations
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What is a population
Group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed
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What is the gene pool
All the alleles of all the genes of all the individuals in a population at any one time
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What is a species
A specific group of closely related organisms which are potentially capable of breeding together (interbreeding) to produce viable, fertile offspring
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What is the allele frequency
the number of times an allele occurs within the gene pool
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what are the 3 kinds of frequency we can measure
Phenotype, genotype, allele
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What is phenotype freq
Easiest because we can see and count them in a population
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What is the genotype freq
Proportions of the 3 possible genotypes BB Bb and bb in the population
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Why isn't it so easy
Because we can't see the genotypes, (use hardy Weinberg) to calc
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What is the allele freq
proportions of the 2 alleles B and b in the population
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What causes them to change
Evolution
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What does the Hardy-weinberg principle provide
A mathematical model which predicts that allele frequencies will not change from generation to generation
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What can it be used to calculate
Frequency of alleles of a particular gene, genotypes and phenotypes in a population
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What does the principle predict?
that proportion of dominant and recessive alleles of any gene in a population remains the same from 1 generation to the next provided that 5 conditions are met
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What are the 5 conditions
no mutations arise, the population is isolated that is there is no flow of alleles into or out of the population, there is no selection that is all alleles are equally likely to be passed on to the next generation, population is large
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5th
, mating within population is random
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What are these conditions?
Propsbly never totally met in a natural population
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What is HW tho
Principle still useful when studying gene frequencies
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What does a gene have
2 allels- a dominant and recessive
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Freq of Dominant=
P
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Freq of Recessive=
Q
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so
P+Q=1
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whY
Only 2 alleles and so freq of one plus other must be 1 or 100%
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How many possible arrangements of the 2 alleles
4
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So it follows that?
freq of all 4 possible arrangement of the 2 alleles added together = 1
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So what can you state ab freq
P^2 + 2pq +Q^2=1
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What is pq
heterozygous
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What do you use it to determine
freq of any allele
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Other cards in this set

Card 2

Front

What is a population

Back

Group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed

Card 3

Front

What is the gene pool

Back

Preview of the front of card 3

Card 4

Front

What is a species

Back

Preview of the front of card 4

Card 5

Front

What is the allele frequency

Back

Preview of the front of card 5
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