10.2 Mendel’s Patterns

10.2 Mendel’s Principals

In the language of genetics, the offspring of two different true-breeding varieties are called hybrids

The parental plants are called the P generation (P for parental), and the hybrid offspring are the F1 generation (F for filial, from the Latin word for "son").

This is an example of a monohybrid cross , a pairing in which the parent plants differ in only one (mono) character.

Today, Mendel's "factors" are called genes

Mendel developed four hypotheses.

1) There are alternative forms of genes. For example, the gene for flower color in pea plants exists in one form for purple and in another form for white. These alternative forms of genes are called alleles

2) If the two alleles are the same, the individual is homozygous (hoh moh ZY gus) for that character. If the two alleles are different, the individual is heterozygous (het ur oh ZY gus).

3) When only one of the two different alleles in a heterozygous individual appears to affect the trait, that allele is called the dominant allele.(expressed)

And in such cases, the other allele that does not appear to affect the trait is called the recessive allele. (masks or hides)

4)The two alleles for a character segregate (separate) during the formation of gametes (sex cells), so that each gamete carries only one allele for each character.

This is known as Mendel's principle of segregation

The type of diagram that shows all possible outcomes of a genetic cross is called a Punnett square

An observable trait (such as purple flowers) is called the phenotype (FEE noh type).(physical)

The genetic makeup, or combination of alleles (such as PP), is called the genotype (gene)

To determine whether the purple-flowered plant is homozygous (PP) or heterozygous (Pp), you need to perform what geneticists call a testcross

A testcross breeds an individual of unknown genotype, but dominant phenotype (your purple-flowered mystery plant) with a homozygous recessive individual-in this case, a white-flowered plant (pp).

Mendel’s Principal of Independent Assortment

_________________- crossing the organisms differing in two characters. (traits) Examples could be color and seed shape. (Lets pick true breeds for parents)

Let’s pick Round = Wrinkled=

Yellow = Green=