Mendelian Inheritance I Flashcards
describe the blending hypothesis
genetic material from 2 parents blend together to form intermediate, ex. blue mom and a yellow dad produces a green offspring
what 2 phenomenons contradicted the blending hypothesis?
uniformity is not observed and there is a reappearance of a trait “lost” in F1 that reappears in F2 (grandchildren) that skipped a generation in F1
what were the benefits of using peas for experiment?
short generation time, many varieties of characters (color, shape, etc), large number of offspring, controllable mating
define hybridization
mating 2 contrasting, true-breeding varieties
crossing
define true-breeding
homozygous, always produces gametes with same alleles/phenotype
What surprise occurred in F1 gen?
recessive trait disappeared
what surprise occurred in F2 gen?
recessive trait returned
What hypothesis did Mendal propose?
Particulate hypothesis: parents pass on genes
what stages could the blending hypothesis be disproven?
F1 and F2
What gen did Mendel observe and deduce segregation and independent assortment law?
F2
What pattern was observed in the F2?
3:1
What is concept 1?
Alternative versions of genes account for variation in inherited characters called alleles
Each gene resides on a locus on a chromosome
What is concept 2?
For each character, an organism inherits 2 copies of a gene, one from each parent
Homozygous and heterozygous concepts
What is concept 3?
If 2 alleles at a locus differ, dominant one is expressed
What is concept 4?
Law of segregation: 2 alleles for a character separate during gamete formation
What is a testcross?
Cross unknown with recessive homozygote- if unknown is homozygous, only dominant phenotype in F1. If half dom half rec, unknown is heterozygous
What is a dihybrid cross
cross between F1 dihybrids…YrRr x YyRr
determined law of independent assortment
define dihybrids
crossing 2 true-breeding parents differing in 2 characters
F1 gen, heterozygous for both characters
What is the law of independent assortment?
each pair of alleles separate independently of other pairs of alleles during gamete formation
law applies only to genes on diff chromosomes or far apart on same one