Fundamentals of Genetics

Gregor Mendel

• Mendel was an Austrian monk who studied genetics by using pea plants.

• Mid 1800’s

Gregor Mendel

• Mendel observed different characteristics of the plants (called traits).

Gregor Mendel

• When he planted the offspring seeds of purple flowered plants, he noticed that the flowers were purple and white.

• This lead to the question of “WHY?”.

Gregor Mendel

• A pure trait is one that always produces offspring with that trait.

Generations

• Parental Generation = P1

• Cross pollination of the P1 generation results in the F1 generation. F = Filial

• Cross pollination of the F1 generation results in the F2 generation.

Recessive vs. Dominant Traits

• Dominant = a trait that hides the presence of another trait for the same characteristic.

• Recessive = a trait that is hidden by the presence of another trait.

Free = Dominant

Attached = Recessive

The Law of Segregation

• A pair of factors is separated during the formation of gametes.

The Law of Independent Assortment

• The factors for different characteristics are distributed to gametes independently.

It’s in your Genes

• A gene is a segment of DNA on a chromosome that controls a particular hereditary trait.

It’s in your Genes

• Alleles are the alternative forms of a gene.

Geno. Vs. Pheno.

• Genotype is the genetic makeup of an organism.

• It is often written with letters such as TT, Tt, or tt.

Geno. Vs. Pheno.

• Phenotype is the external appearance of an organism.

• Such as Tall, Short, Green, Yellow

Hetero. Vs. Homo.

• “Homo” means the same

• “Hetero” means different

• Homozygous dominant : TT

• Heterozygous: Tt• Homozygous

recessive: tt

Probability

• The likelihood that a specific event will occur.

• It is expressed as a decimal, percent or fraction.

Probability

• Formula

# of times an event is expected to happen

# of opportunities for an event to happen

Punnett Squares

• Used to predict probability in various crosses.

Monohybrid Cross

• Involves only one pair of contrasting traits.

Dihybrid Cross• Involves two pairs of contrasting traits.