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EXAM 4 - Coggle Diagram

- - - - Each chromosome has a partner
      - Homologous chromosomes
      - Resemble each other in size, shape & hereditary information
      - Each homolog is from a different parent
      - Interactions of genes on each sets of chromosomes determines the genetic characteristics
    - - During Metaphase I
      - Orientation of bivalents is random
      - During Metaphase II
      - Orientation of sister chromatids is random
      - In general, the possibilities are 2n
      - Ex: human with 46 chromosomes
      - 246 = 7.04 x 1013
    - - During Prophase I
      - Synaptonemal complex forms
      - Mixes the genes present in homologous chromosomes
      - Results in new combinations not present in the chromosomes of the parental cells
      - Usually at least one chiasma occurs between every pair of homologous chromosomes
    - - New combination of alleles from each parent
      - Promotes heterozygosity
      - Advantages include
      - genetic diversity
      - Bet-hedging to novel environments
      - Multiple deleterious alleles can be bunched together and eliminated
      - Escape host-parasite negative impacts
      - Pollination
      - Cross pollination vs
      - Self pollination
  - - - Dominance
      - Segregation
      - Independent Assortment
    - - Each individual has a unique genotype
      - Genotype is made up of alleles
      - Phenotypes determined by these alleles (and the environment)
      - There is no guarantee that an allele will manifest
      - Heterozygosity
      - One of 2 genes (dominant allele) has a detectable effect on an organism's appearance
      - The other gene has no discernable effect (recessive allele)
      - Homozygosity, both alleles are the same
    - - Alleles are segregated, separated, from one another during meiosis
      - Each gamete contains only one allele for each gene
      - Offspring inherit 2 alleles for a gene
      - One from each parent
      - Inherit a homologous chromosome
      - During meiosis, 2 members of a gene pair separate from each other
      - Each gamete has an equal chance to inherit either one of the genes
    - - Punnett square
      - Visual representation of the offspring inheritance patterns
      - Monohybrid is a cross between 2 homozygous parents with different alleles.
    - - Gene pairs that are not related (homologs) segregate independently
      - Gene pairs that are not linked segregate independently
      - Evidence provided from a dihybrid cross
      - 3:1 phenotypic ratio for each of the 2 alleles
  - - - Phenotype of heterozygote is intermediate between those of parent homozygotes
      - Snapdragons
      - Red x white = pink
    - - Many populations have more than 2 alleles for a particular locus
      - Punnett square theoretical crossing works similar
      - Breeding experiments to determine dominance
      - Figuring out alleles is complex
    - - Changes in the genetic makeup of an individual
      - Point mutation
      - Single nucleotide change
      - Chromosome mutation
      - Deletion
      - Segments of chromosome are lost
      - Duplication
      - Part of the chromosome has doubled
      - Inversion
      - Piece rotates 180
      - Translocation
      - Exchange of parts between 2 nonhomologous chromosomes
      - Transposons
      - Movable genetic element
      - Jumping genes
    - - Fail to mix alleles across homologs
      - Chromosome inherited same as parent
      - Only 2 gamete types possible rather than 4
    - - Multiple genes for one character
      - Phenotype is cumulative result of combined effects of many genes
      - Example abscisic acid
      - Most traits
      - Continuous variation
      - Populations tend to have normal distribution
    - - One gene interacts with another
      - May interfere or mask
      - Ex: digitalis petal color
      - One gene impacts red intensity
      - d light red
      - D dark red
      - Pigment location
      - w throughout corolla
      - W spots of nectar guide
    - - 4 haploid genotypes
      - Not produced in equal numbers
      - Recombinants less abundant
      - Parentals more abundant
    - - Single gene with multiple effects on the phenotype
      - Inheritance of a single gene which visibly influences several traits
      - Ex: awn of wheat
      - Wheat with awns have greater yield than those without awns
    - - Selfer
      - Small petals
      - Flower early
      - Seasonal drought
      - Physiologically escape?
      - Outcrosser
      - Large petals
      - Flower late
      - Seasonal drought
      - Physiologically tolerant?
    - - Having more than two copies (2n) of a chromosome
      - Autopolyploid
      - Failed meiosis
      - Self fertilization
      - Allopolyploid
      - Meiotic error
      - Mismatch during mating
      - Second mating creates matched pairs
    - - Wheat
      - Result of sequential hybrid doubling and quadrupling
      - Original ancestral species had 14 chromosomes
      - Durum wheat
      - 28 chromosome
      - Tetraploid
      - pasta
      - Bread wheat
      - 42 chromosome
      - Hexaploid
      - Gluten for lofty bread
    - - Polyploid mask deleterious recessive alleles
      - Relax selection pressure
      - Accumulate mutations that eventually result in beneficial trait
      - 2 groups of ancient duplications
      - Common ancestor of seed plants
      - Common ancestor of extant angiosperms
- - - - Allele frequency
      - Number of copies of an allele in a population divided by the total number of alleles for that gene in a population
      - Genotype frequency
      - Number of individuals with a particular genotype in a population divided by the total number of individuals in a population
    - - Number of copies of an allele in a population
      - Divided by
      - The total number of all alleles for that gene in a population
    - - Number of individuals with a particular genotype in a population
      - Divided by
      - The total number of all individuals in a population
    - - predicts an equilibrium-unchanging allele and genotype frequencies from generation to generation-if certain conditions exist in a population
      - No new mutations
      - No genetic drift. The population is so large allele frequencies do not change due to random sampling effects
      - No migration
      - No natural selection
      - Random mating
      - provides a quantitative relationship between the allele and genotype frequencies
    - - If, instead, we always use p and q rather than choosing an upper and lowercase letter to represent alleles:
      - The frequency of the dominant allele is represented by p
      - The frequency of the recessive allele is represented by q
      - Thus p+q=1
      - Therefore (p+q)2=12;
      - And p2+2pq+q2=1
      - p2= genotypic frequency of RR
      - 2pq= genotypic frequency of Rr
      - q2= genotypic frequency of rr
  - - - Changes in a population’s gene pool from generation to generation
      - Factors
      - Mutation
      - Natural selection
      - Genetic drift
      - Migration
      - Nonrandom mating
    - - Change in one of the nucleic acids
      - Some are apparent in phenotype
      - Source of all new alleles
      - Must be in gametes to be inherited
      - Male pollen sperm
      - Female ovule egg
    - - Dimorphic
      - 2 phenotypes
      - Dominant-recessive systems
      - Polymorph = many phenotypes in a population
      - Example: Aquilegia
      - Color variation
      - Spur-length variation
      - Can be due to a single nucleotide polymorphism
    - - Random loss of alleles
      - Acts most strongly in small populations relative to large
      - Bottleneck effect
      - Large population diminished suddenly
      - Natural catastrophe
      - Migration
      - May increase in size again but unlikely to regain original diversity
    - - Plants “choose” their mates
      - Pollinator vectors
      - Pollination syndromes
      - Some of the individuals reproduce more than others
      - Based on individual phenotypes
    - - Male-male competition
      - Excess of pollen grains
      - Pollen tubes can interfere with one another
      - Female choice
      - Barriers on stigma surface preventing germination
      - Male-male competition
      - Excess of pollen grains
      - Pollen tubes can interfere with one another
      - Female choice
      - Barriers on stigma surface preventing germination
    - - Movement of alleles into and out of a population
      - Immigration
      - Into
      - Emigration
      - Out of
      - Can be impeded by
      - The environment
      - Life history
      - Repercussions for
      - GMO and
      - climate change
      - speciation
    - - Bottleneck from long distance dispersal
      - Followed by adaptive radiation
      - Example: Hawaiian lobeliads
    - - One allele selectively advantageous
      - In this example, 2 (triangle) has more vigorous offspring
      - Over time, individuals with the 2 genotype are able to reproduce more and grow in numbers
      - The overall vigor of the population grows
      - So does population size
    - - Selection by humans
      - Increased frequency of desired trait
      - Elimination of undesired traits
      - Crop breeders for thousands of years
      - Example Brassica
  - - - Steps summarized
      - Find your Min & Max values
      - Determine the number of bins
      - Count the number of observations for each bin
      - Draw bars for each bin with the frequency
    - - Death does not mean natural selection has occurred
      - Differential survival
      - Survival due to phenotypes that are heritable
      - Phenotype coded by genotype