Download Genetics

Genetics
The branch of biology that studies
heredity
Gregor Mendel
 The Father of Genetics
 An Austrian Monk during the mid nineteenth
century
 Used garden pea plants to make his
discovery that traits are passed from parent to
offspring
Important Vocabulary
 Trait- characteristics that are inherited
 Gamete- sex cells (ex..in humans sperm and
egg)
 Fertilization- the uniting of male and female
gametes
 Hybrid- the offspring of parent that has
different forms of a trait (ex. Tall and short
height)
Important Vocabulary
Mendel’s Discoveries
 The rule of unit factors : each organism has
two factors that control each of its traits. The
factors are called alleles.
 One allele is inherited from the female parent
and one from the male parent.
Mendel’s Discoveries
 The rule of dominance:
when a dominant
allele is present you will see it.
 You will only see a recessive allele when
there is no dominant allele present.
Mendel’s Laws
 The Law of Segregation states that alleles
randomly pair during fertilization.
 The Law of Independent Assortment states
that different traits are inherited independently
of each other. Example seed shape and
seed color have no influence on each other.
Monohybrid cross
 T- stands for tall
 t – stand for short
 Dominant traits are always
written with a capital letter.
Dominant alleles will always
be seen if they are present.
 Recessive traits are always
written with a lower case
letter. One can only see a
recessive trait when a
dominant trait is not present.
You must have two recessive
alleles.
Phenotype- the way the offspring look
 The phenotype of the
F1 generation of the
monohybrid cross is all
tall.
Genotype- the actual allele
configuration of the offpring
 The genotype of the F1
generation is “all Tt” or
“all heterozygous”-
Heterozygous vs. Homozygous
 Heterozygous means a
 Homozygous means
dominant allele and a
recessive allele is
present .
 Examples: Tt, Yy, Pp
there is only one form of
the allele present.
 Examples: tt, TT, YY,
yy, PP, pp
 Offspring can be either
homozygous dominant
(TT) or homozygous
recessive (tt).
Monohybrid Cross
 Yy x Yy
 Y-Yellow pea
 y- green pea
 What is the phenotype
of this F1 generation?
 What is the genotype of
this F1 generation?