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

Do Now:

What is a trait, name a few

Gregor Mendel- The first scientist to experiment

with inheritance

Genetics: the study of heredity

• These characteristics that Mendel could see are known as – TRAITS

• Specific characteristics of an individual.

Alleles-alternative forms of genes (ex: purple flower or white flower) -- 2 alleles for the gene, one from each parent

• 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)

• Homozygous: an individual with two of the SAME alleles

• Heterozygous: an individual with two DIFFERENT alleles

• When Mendel crossed a purple flower with white flower all offspring were purple.

• What allele is dominant?– Purple

• Which means white is recessive.– Has the ability to pop

up later

How do we express dominant vs recessive alleles?

• Using Capital and Lower case Letters.

• Capital = dominant

• Lowercase = recessive

• So using the pea plants flower color…

• P = purple

• p = white

• This combination of alleles is referred to as the

GENOTYPE: allele combination (PP, Pp, pp)– Heterozygous or homozygous

• The traits you actually see is referred to as your– PHENOTYPE: Physical features, characteristics

you see from the genotype

Other Types of Inheritance…• Incomplete Dominance: neither allele is

dominant. A mixture of two alleles will show

Example – ]:

• White chicken (WW) x black chicken (BB)

Grey chicken (WB)

1 black (BB) + 2 Grey (WB) + 1 white (WW)

Both genotypic and phenotypic ratio = 1:2:1

WB WB

WBWB

BB

W W

W B

W

B

WW

WB

WB

BB

Try This

• Flower color is an example of incomplete dominance in roses. You are crossing a red rose with a white rose. What will the results of the F1 generation be?

Show your results and then do a cross of the offspring from the F1 generation and give the phenotypic and genotypic ratios of the F2 generation.

Codominance

• Both alleles are dominant, so both alleles show (NOT A MIX like in incomplete dominance )

• Example blood type (Type AB)

Multiple alleles shows codominance where both traits are expressed equally (not a mixture of the two)

Cross a heterozygous type A withwith a heterozygous type B

A O

B

O

AB BO

OOAO

• Cross a type AB blood individual with a type O

A B

O

O

AO BO

BOAO