Genes L8 Flashcards
What is microevolution?
- Changes -> gene pool -> organism -> overtime
What is a gene pool?
- All alleles of all genes -> all individuals -> population.
- Represents genetic variation -> population
What are alleles?
- Different forms/types of gene -> polymorphisms.
Mutation
What is the term polymorphic used to describe?
- Gene locus with more than one allele
What is macroevolution?
• Macroevolution: - Large scale evolution - Evolution across major animal groups Above species level Eg. Phyla, Order, Phyla etc. - Speciation
Contrast microevolution & macroevolution.
• Macroevolution: - Large scale evolution - Evolution across major animal groups Above species level Eg. Phyla, Order, Phyla etc. - Speciation
• Microevolution:
- Evolution within species or population
- Microevolution & Chance -> macroevolution.
What results in macroevolution occurring?
- Microevolution & Chance -> macroevolution.
Requirements for evolution by natural selection?
- Varying reproductive successes
- Genetic variation -> (Differences between individuals)
What is evolution?
• Evolution -> changes -> genetic structure -> population/species -> over time.
Describe what population genetics is.
• Population genetics
- Study of genetic changes -> evolution.
- Study of microevolution
>Darwin’s theory -> evolution by natural selection
> Mendel’s theory -> inheritance
- Modern synthesis / neo-Darwinism
What can population genetics be used to investigate in terms of human pathogens?
Evolving human pathogens
Human evolution in response to pathogens
Use of population genetics in investigating evolving human pathogens?
Evolving human pathogens: - Bacteria -> Antibiotic resistance Eg. MRSA - Viruses -> Anti-viral drug resistance Eg. HIV - Emerging pathogens Eg. Ebola, influenza viruses
Use of population genetics in investigating human evolution in retaliation to pathogens?
Human evolution -> pathogens:
- Resistance
- > blood-bourne parasites Eg. Malaria parasites, Plamodium sp.
Use of population genetics in wild populations?
• Uses of population genetics in wild populations:
- Range/quantity & distribution -> genetic diversity
- Response -> population -> change
Describe the gene locus model & what is is used for.
• Single gene locus model - Used to study gene pool - Diploid organisms >Single gene >> 2 alternative alleles i) R -> dominant ii) r -> recessive - 3 genotypes RR -> Homozygous Rr -> Heterozygous rr -> Homozygous >> 2 phenotypes RR & Rr -> red flower rr -> white flowers
What is a genotype?
• Genotype:
- The genetic composition of an organism determining a particular characteristic (phenotype).
What is a phenotype?
• Phenotype:
- Observable characteristics of an organism as a result of interaction between it’s genotype & their environment.
What is measured in the gene pool? Describe how both of these are calculated.
- Allele/Allelic frequency:
(Number of particular type of allele)/(Total number of alleles) - Genotype/Genotypic frequency:
(Number of individuals with one particular genotype)/(Total number of all individuals)
Describe the Hardy-Weinburg equilibrium.
• Hardy-Weinburg equilibrium: - Allele & genotype frequencies reach an equilibrium over time & remain unchanged. - p2 + 2pq +q2 = 1 Genotype frequency: f(RR) + f(Rr) + f(rr) =1 Allele frequencies -> p & q >> p + q = 1 Conditions: Large population size Random reproduction No migration of populations No selection No mutation
Equation of genotypic frequency for H-W eqm?
- p2 + 2pq +q2 = 1
Genotype frequency: f(RR) + f(Rr) + f(rr) =1
Equation of allelic frequency for H-W eqm?
Allele frequencies -> p & q
|»_space; p + q = 1
What is the definition of the H-W principle and what are it’s conditions?
- Allele & genotype frequencies reach an equilibrium over time & remain unchanged. Conditions: Large population size Random reproduction No migration of populations No selection No mutation
Calculate the allelic frequency for both allele types from a population of 100 in which 40-> homozygous dominant
50-> heterozygous & 10-> homozygous recessive.
- F(A1A1) = 40/100 = 0.4
- F(A1A2) = 50/100 = 0.5
- F(A2A2) = 10/100 = 0.1
- Allele frequency A1 = (No. of A1 alleles)/(Total no. of alleles)
[2(40) + 50]/200 = 130/200 = 0.65
Allele frequency: If 100 genotypes – 2 alleles per genotype -> 200.
Dominant alleles -> Homozygous dominant -> A1A1
-> 2 dominant alleles per homozygous dominant genotype
Heterozygous -> A1A2 -> 1 dominant allele per heterozygous.
Homozygous recessive -> A2A2 -> No dominant alleles per genotype
» No. of alleles = 2(No. of homozygous dominant genotype) + 1(No. heterozygous genotype)
- Allele frequency A2 = (No. of A2 alleles)/(Total no. of alleles)
[50 + 2(10)]/200 = 70/200 = 0.35.
Recessive alleles -> homozygous recessive -> A2A2
->2 recessive alleles per homozygous recessive genotype
Heterozygous -> A1A2 => 1 recessive allele per heterozygous genotype
Homozygous dominant -> A1A1 -> No dominant alleles per genotype
»_space; No. of recessive alleles = 2(No. of homozygous recessive genotype) +
1(No. of heterozygous genotype)
• If 70% of population of has dominant (R) allele, calculate the genotype frequencies of the population.
p+q=1 p=0.7 -> q=1-0.7 -> 0.3 Genotype frequencies: f(RR) + f(Rr) + f(rr) = 1 p2= (0.7)2 -> q2= (0.3)2 (0.7)2 + 2pq + (0.3)2 = 1 2pq = 1 -0.58 -> 0.42 pq= 0.42/2 -> 0.21 p2 = homozygous dominant (RR) > (0.7)2 ->0.45 q2 = homozygous recessive (rr) > (0.3)2 -> 0.09 2pq = heterozygous (Rr) > 2(0.7)(0.3) = 0.42