Molec and Cell 4

sperm contained fully formed “little people Like begets like: offspring are like their parents Everything from the egg: females controlled all traits

males control all traits

offspring were the average between both parents

changes happening to parents could be passed on to offspring

the idea that particles called “gemmules” carry the traits we inherit.

Considered the father of genetics Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments

A heritable feature that varies among individuals (such as flower color)

Each variant for a character, such as purple or white color for flowers

plants that produce offspring of the same variety when they self-pollinate

a process of mating two contrasting, true-breeding varieties

true-breeding parents

The hybrid offspring of the P generation

When F1 individuals self-pollinate or cross-pollinate with other F1 hybrids

the characteristic version of a trait we actually see. Example: purple flower or blue eyes

specific versions of a “hereditary particle” (today= versions of a gene)

alternative versions of genes account for variations in inherited characters

that for each character an organism inherits two alleles, one from each parent

For independent events A and B, the probability (P) of both occurring (A and B) is (PA x PB)

For mutually exclusive events A and B, the probability (P) that at least one occurs (A or B) is (PA + PB)

if the two alleles at a locus differ, then one (the dominant allele) determines the organism’s appearance, and the other (the recessive allele) has no noticeable effect on appearance

known as the Law of Segregation, states that the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

individuals that are heterozygous for one character

A cross between such heterozygotes

Crossing two true-breeding parents differing in two characters, heterozygous for both characters