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50 terms

Population Genetics

STUDY
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P= 0
impossible event
P= 1
certain event
Addition Rule
For mutually exclusive "OR" events, you add the probabilities
Multiplication Rule
For independent "AND" events multiply the probabilities
Allele
alternative forms of a particular gene that are present at a single locus.
Alelle Frequency
the proportion of a specific allele relative to all other alleles in a population
Genotype frequency
The proportion of a specific genotype relative to all other genotypes in a population
Phenotype frequency
The proportion of a specific phenotype relative to all other phenotypes in a population
p+q=1
For two alleles, present in a population, the relative frequencies are equal to 1
Hardy Weinberg Equilibrium Conditions
Random Mating, Infinitely large population, No mutation, No migration into or out of the population, No selection for either trait
Assortative Mating
like mating with like, where partners select each other based on a shared trait or characteristic
Consanguineous mating
matings between closely related individuals
Fixative Genes Can Lead to
Small Population Size
Random Genetic Drift
allele frequencies in a population change from one generation to the next due purely to chance
Founder effect
Specific alleles that are more rare, become not as rare
Bottleneck
deleterious alleles are amplified, when a population decreases then reproduces again
Dunker Blood type
example of Founder effect
Selection
Differences in reproductive or Genetic Fitness
Heterozygote advantage
Hemoglobin S allele confers resistance to malaria
CFTR
heterozygote resistant to diarrheal disease
HEXA
heterozygote resistant to tuberculosis
PAH
heterozygote resistant to abortion caused by fungus
Gene Flow
Migration, slow diffusion of alleles across a racial or geographical boundary
q^2
the freq. of homozygotes for the a allele
p^2
the freq. of homozygotes for the A allele
2pq
the freq. of heterozygotes
Disease Frequency= (for autosomal recessive)
q^2
Females allele frequency of X-linked genes; genotype frequency
p+q=1; p^2+2pq+q^2=1
Males genotype frequency for X-linked traits; allele frequency
p + q=1; p+q=1
Fitness
the measure of the number of offspring of affected persons who survive to reproductive age. Ranges from 0-1
Coefficient of Selection
1-f, or s
Autosomal dominant traits (mutations equation)
u= sq or u=(1-f)q
X-linked recessive if the phenotype is benign
u=sq/3 or u= (1-f)q/3
x-linked genetic lethality, where mutation causes a very deleterious phenotype
1/3 of all copies of mutant allele will be lost in each generation
Coefficient of relationship (def.)
a measure of the proportion of genes shared by two related individuals as a result of their genetic relationship
Coefficient of relationship (equation)
1/2^n
Coefficient of Inbreeding (def)
a masure of the probability that a person has received both alleles of a gene from a common ancestor
Coefficient of Inbreeding (equation)
1/2*1/2^n= 1/2^(n+1)
Mutually exclusive
either one outcome or the other will occur
Independent
when the probability of one event does NOT effect the probability of another event's occurrence
Prior probability
The initial probability of an event
Conditional probabilities
probabilities determined by observations or posterior information
Joint probability
probability resulting from multiplication of the prior probability with each appropriate conditional probability
Posterior Probability
Probability resulting from dividing the joint probability for each event, by the sum of the joint probabilities
Autosomal dominance risk for passing on mutant allele to offspring
1/2
Example of delayed onset disease
huntington's
Autosomal recessive risk for passing on mutant allele to offspring
1/4
Autosomal recessive risk for producing children that are heterozygous
2/3
For sex linked recessive traits, affected males...
daughters will all be carriers
Carrier mothers of sex-linked recessive traits
1/2 of sons will be affected