genetics
TRANSCRIPT
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…