population genetic

• A gene pool is the total genes possessed by males and females of a population.
• • Genes:
  • Exhibit continuity.
  • Genotypes:
  • Lack continuity.
• Transmission of Genes

  • Process involves:
  • Breakdown of parental genotypes.
  • Formation of a new set of genotypes in progeny.
• Genetics of a Population

  • Concerned with:
  • Genetics constitution of individuals.
  • Transmission of genes from generation to generation.
• Examples of Quantitative Traits

  • Body weight
  • Weight gain
  • Milk production
  • Wool yield
  • Egg yield
• Population Genetics

  • Definition: A breeding group of individuals.
  • Study Focus: Genetics of a population.
  • Also Known As: Quantitative Genetics.
• Quantitative Genetics

  • Focus: Inheritance of differences in quantitative characters.
• migration ?

  the movement of genes into or out of the population
• migration is also called?

  gene flow, microevolution
• natural selection -?


  results in the survival and reproductive success of individuals or groups best adjusted to their environment
• genetic drift ?

  reduction in the gene pool variation caused purely by chance usually in small population
• no genetic drift means that ?

  the number of parents is sufficiently large and the number of offspring also
• factor that cause genetic drift?

  the bottle neck effect the founder efffect
• no selection means ?

  each genotype has the equal pooprtunity to contribute offspring and each off has the euqal opportunity to survive
• Repeatability repersents the degree of association between measurements on the same animal for traits which are measured more than once
• Traits which can be measured with repeatability

  litter size, lactation milk ield and fleece weight
• the between individuals component is partly environmental and partly genetics
• the within individual component is entirely environmental
• within individual components is also known as special envrionmental variances
• repeatability is used in perdicting futute records for an animal that has one or more previous record
• heritability is used for both the estimation of breeding values for quantitative characteristics and for predicting the responese expected from various selection plan
• heritability in broad sense describes what proportion of the total variation is due to differences among genotypes of individuals in the population
• h squared is the proprtion of the total variance that is due to differences among the breeding values of individuals in the population
• Mutation occurs in two forms

  point mutation = these involve the alteration of single base

  gross mutation= these involve alteration of longer DNA sequences
• mutation occurs within the coding region are likely to affect the protein syn
• mutation in non-coding region do not usually have an effect
• missense mutation changes one of the first two bases of codon
• the alteration of amino acids in parts of protein that are important for structure or function are more likely to have a deleterious effect
• mutation can arise ue to errors introduced during DNA replication that result from the action of chemical and physical agents or alteration to the usual DNA sequence of an organism
• types of point mutation

  missense

  nonsense

  frame shift

  silent
• types of gross mutations

  Deletions

  Insertions

  Rearrangement
• in nonsense mutation the codon for an amino acid change into a termination or stop condon
• N/s mutation causes translation of mRNA to end prematurely resulting ins shortened prtoein
• N/s mutations have

  a serious effect on the activity of encoded protein

  produce mutant phenotype
• Frame shift mutation

  • result form the insertion or deletion of extra bases from the DNA sequence of a gene.
• F/s mutation have

  serious effect on the encoded protein

  assiociated with mutant phenotypes
• Silent Mutation

  occur at the third base of codon

  amino acid will not be altered

  no effect on encoded protein and not result in mutant phenotype
• polymorphism

  the accumulation of silent mutation in the DNA of organisms
• deletions

  the loss of a portion of the DNA sequence

  can be as small as a single base or much lager

  in some case to the entire gene sequnce
• Insertion

  a result of insertion of extra bases

  usually from another part of chromosomes

  amount inserted may be one or two bases