12/18/13

Objective: Who was Gregor Mendel and what were his contributions to genetics?

Do Now:

Why is there so much variation in sexually reproducing organisms?

TraitsTraits: a variation of a particular

character (ex: blue eyes or brown eyes)

Blending Hypothesis- A hypothesis to explain

inheritance What color flower might you expect to

get if you crossed a red and yellow flowered plant?

- Blending of parental traits

Gregor Mendel- The first scientist to experiment

with inheritance

Genetics: the study of heredity

Particulate Hypothesis

- Parents pass on to their offspring separate and distinct factors (genes) responsible for inherited traits

Pure-breeding

- Mendel used true-breeding pea plants to experiment with genetics (purple flowers produce purple flowers)

Hybrids

- The offspring of 2 different true breeding varieties (ex: a purple and a white flower)

Parental plants = p generation

Hybrid offspring are called the:

First filial = F1 generation

When the F1 plants self-fertilize or fertilize each other they are the

Second filial = F2 generation

• Alleles: - alternative forms of genes (ex: purple flower

or white flower) - - 2 alleles for the gene, one from each parent

• Homozygous: an individual with two of the SAME alleles

• Heterozygous: an individual with two DIFFERENT alleles

• Dominant: A trait that will appear in the offspring if one parent contributes it, capital letter (B= Brown eyes)

• Recessive: a trait that must be contributed by both parents in order to appear in the offspring, lower case letter (b= blue eyes)

• Crossing 2 parent plants that differ in only one character (trait)

• Law of segregation: When a parent forms sex cells (egg or sperm), the parent’s gene pairs separate, so the sex cells carry only 1 allele for a particular trait

• Law of independent assortment: Each gene ppair for a trait is inherited independently of the gene pairs for all other traits.

• Law of Dominance: Each allele modifies the phenotype to some degree, producing a blended trait