genetics

Genetics…simple concepts

What is genetics? The study of heredity

The passing of characteristics from parents to offspring

Traits

Gregor Mendel…

The first person to predict successfully how traits are transferred from one generation to the next.

He experimented with garden pea plants.

Gametes?

Male and female sex cells.

When these two join through fertilization, a zygote is produced.

Hybrids…The offspring of parents that have different forms of a trait.

Tall (T) Short (t)

hybrid

A discovery… Mendel, experimenting with the pea plants, discovered that everyorganism has two genes that control the outcome of a trait.

Tt = tall tt = short* each gene is represented by a letter

AllelesGenes exist in different forms…

Allele 1 Allele 2 Trait Allele 1 Allele 2 Trait

T t = tall t t = short

Dominant or Recessive? • Even though for each trait there are two alleles, only one of them actually shows…

The trait that we can observe Dominant

The trait that disappears Recessive

An example with plants…

If a plant has a combination… in which T is tall and t is short…

The plant will be tall… T is the dominant allele (tall)

t is the recessive allele (short)

Phenotype vs. GenotypeThe difference is simple…

A phenotype is the way an organism looks and behaves.

A genotype is the allele combination an organism has.

The law of segregation

“Every individual has two alleles of each gene, and when gametes are

produced, each gamete recieves one of these alleles”

orIndividual gamete Individual gamete

Homozygous or Heterozygous? The alleles don’t always have to be different…

When the alleles for a trait are the same (TT) (tt) HOMOZYGOUS

When the alleles for a trait are the different (Tt) HETEROZYGOUS

Remember…

Homo = same

Hetero = different

The end…