Hypothesis of Heredity

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2 hypothesis of heredity
o“Blending” hypothesis: you are a mixture of genetic information from your parents. (bucket of paint) o“Particulate” hypothesis: you receive discreet packets of genetic information, passed on undiluted to future generations. (bucket of marbles) •Mendelian genetics

oCharacter: inheritable feature, i.e., fur color
oTrait: variant for a character, i.e., brown
oTrue-bred: all off-spring of same variety
oHybridization: crossing of two different true-breds
oP generation: parents
oF1 generation: first filial generation
Leading to the law of segregation
oAlternative versions of genes (alleles) account for variations in inherited characteristics. oFor each character, an organism inherits 2 alleles, one from each parent. oIf the two alleles differ, then one, the dominant allele, is fully expressed in the organism’s appearance, the other, the recessive allele, has no noticeable affect on the organism’s appearance. oThe alleles for each character segregate (separate) during gamete production (meiosis). •Genetic Vocabulary

oPunnet square: predicts the results of a genetic cross between individuals of a known genotype. oHomozygous: pair of identical alleles for a character (ex/ pp) oHeterozygous: two different alleles for a gene (ex/ Pp)

oPhenotype: an organism’s traits.
oGenotype: an organism’s genetic makeup.
oTestcross: a cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive for that trait so the unknown genotype can be determined from the offspring. •Law of independent assortment

oLaw of segregation involves 1 character. What about 2 or more characters…? oMonohybrid cross (hybridization using a single trait with two alleles) vs. Dihybrid cross (hybridization using two traits with two alleles each) oThe two pairs of alleles segregate independently of each other. •Non-single gene genetics

oIncomplete dominance: appearance between phenotypes...
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