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Genetics - Coggle Diagram

- - - - linked genes = genes close together in a chromosome
        
        tend to be inherited together in crossing over
        
        genetic map = ordered list of locations of genes within a chromosome
  - - - can result from nondisjunction
        
        trisomy = 3 chromosomes
        
        monosomy = 1 chromosome
        
        polyploidy = extra chromosome sets
    - - usually caused by trisomy of chromosome 21 (trisomy 21)
        
        other examples = cancer, other genetic disorders
  - - - XX = female
      - Xy = male
    - - Usually on X chromosome
  - - - Phenotypic affects of genes depend on what inherited from parents
        
        Some diseases caused by diseases in genes that prevent cells form making ATP
  - - - Genes located in chromosomes
        
        Behavior of chromosomes during meiosis accounts for mendel's laws
- - - - Epistasis
        
        phenotypic gene expression in one location affects expression in another
      - Polygenic Inheritance
        
        Quantitative characters = features that vary continuously over range (as opposed to simple mendelian "either-or" (purple OR white flower color)
        
        polygenic inheritance = 2+ genes affect single phenotypic characer
    - - Environmental factors affect gene expression
        
        Examples
        
        Plants
        
        wind + sun affect leaf size, shape, etc.
        
        Humans
        
        Nutrition affects height, skin tans in sun, etc.
    - - Frequency of Dominant Alleles
        
        Dominant alleles not always more common than recessive
        
        e.g. polydactyly
      - Multiple alleles
        
        Most genes have 2+ alleles
        
        E.g. blood type alleles
      - Dominance vs Phenotype
        
        Dominant/recessive genes do not interact
        
        Example: tay-sachs disease
      - Pleiotropy
        
        When genes have multiple phenotypic affects
      - Degrees of Dominance
        
        Incomplete dominance
        
        Neither allele is completely dominant (leads to mixed phenotype)
        
        Codominance
        
        Both alleles dominant simultaneously
        
        Both affect phenotype in different ways
        
        Complete dominance
        
        One allele completely dominant over the other
  - - - Multiplication rule
        
        probability of both events happening = each individual probability multiplied
      - Addition Rule
        
        Probability of 2+ mutually exclusive events occurring = individual probabilities added together
    - - Probability rules can be applied to outcomes w/ multiple characters
        
        Can be used instead of complex punnett squares
  - - - Mendel's model
        
        Alleles = versions of a gene (e.g. white vs purple gene)
        
        Organism gets both versions for each character
        
        Dominant allele = determines organism's appearance
        
        Recessive = no effect on phenotype
        
        Law of segregation = The 2 alleles segregate + end up in different gametes
        
        Punett square = predicts likelihood of different allele combinations
      - Genetic vocabulary
        
        Phenotype = the genes/alleles that are visibly/observably expressed
        
        Genotype = entire genetic makeup, whether expressed or not
        
        Heterozygote = 2 different alleles
        
        "heterozygous"
        
        E.g. Pp
        
        Homozygote = has identical allelles
        
        Called "homozygous"
        
        e.g. PP
      - Mendel found ~3:1 ratio of white to purple flowers in F2 generation
      - The Testcross
        
        Testcross = breeding organism w/ unknown genotype with a recessive homozygote
        
        Can reveal genotype of unknown specimen
    - - dihybrid = 2 genes/alleles involved (e.g. yellow and wrinkled seeds)
        
        dihybrid cross = crossing of dihybrid organisms
      - Law of independent assortment = allele pairs separate randomly when gametes formed
      - monohybrid = parents heterozygous for a particular gene/character
        
        monohybrid cross = cross between monohybrid organisms
    - - Mendel = Austrian Monk and Scientist
        
        Studied genetic inheritance in pea plants
      - Characters vs Traits
        
        Characters
        
        Variable features that are hereditary (e.g. flower color)
        
        Traits
        
        Each variant for a character (e.g. purple, blue, white, etc.)
      - Process
        
        Carefully cross-pollinated true-breeding pea plants of 2 different colors
        
        hybridization = mating of 2 true-breeding variees
        
        offspring = F1 generation
        
        F1 offspring = F2 generation
        
        Parents = p generation