Understand how sexual reproduction (i.e. the combination of meiosis and fertilization) results in a large genotypic and phenotypic diversity Flashcards
Differentiate expected proportions of gametes/offspring from observed proportions of gametes/offspring
Expected is the expected frequencies of allele combinations that we would expect in the next generation based on the parent generation and the observed is the actual data that we collect after completing the cross.
What is the and/or rule and give an example
the and/or rule is a way to calculate the probability of something occurring, we in biology use it mainly to calculate genetic probability. A good example would be if a question asked “what is the probability that a woman will give birth to 3 boys OR 3 girls?” we first want to know the probability of having a boy or a girl and we know that is 50-50 so we would multiply .50 by 3 (number of children) which gives us .125 and that number represents the probability of the woman giving birth to specifically one gender but the question is asking 1 OR the other so in this case, we would just add .125+ .125 to get .25 which the probability of her giving birth to 3 boys OR 3 girls. put simply the And rule is multiplying the probabilities together and the Or rule is adding probabilities together
Justify (explain in your own words) why any particular cross between parents of known genotypes results in a particular ratio of potential offspring genotypes and phenotypes.
The best way to explain this is through an example. if homozygous recessive individual mates with a homozygous dominant individual we expect that because each parent can only give one gamete the child would have a 100% chance of being heterozygous. a harder example would be two heterozygous individuals mating. in that case, it would be a 1:2:1 ratio of 25% chance that the child will be homo dominant and 25% that they would be recessive, and 50% that they would be heterozygous. so the phenotypic probability would be 25% chance of being recessive and 75% of being dominante
how can we use genotypic (or phenotypic) ratios of offspring to predict the genotypes of parents
if we know the percent chances that different crosses provide then we can look at the ratio of offspring phenotypes and genotypes to backtrack and figure out what alleles must have been contributed and then once we know that we need to figure out the parent’s genotypes. I would find this by drawing a pedigree and would just work from the bottom up
how does independent assortment relate to gamete and genotypic frequencies in crosses involving more than one gene (specifically, what assorts, and when during meiosis do they happen?)
In meiosis I, crossing over during prophase and independent assortment during anaphase creates sets of chromosomes with new combinations of alleles. Genetic variation is also introduced by random fertilization of the gametes produced by meiosis.
Predict phenotypes resulting from polygenic traits that result in quantitative phenotypic trait distributions (simple additive polygenic inheritance).
Polygenic inheritance refers to a single characteristic that is controlled by more than two genes for example the fur color of a dog can be a trait that is controlled by multiple different genes if both dominate the color would for example be black if one is recessive and the other dominate the color would maybe be gray and if it was received it would say, white.
