Transcript Mendel`s Work

Mendel’s Work
What is Heredity?
• The passing on of
characteristics (traits) from
parents to offspring
• Genetics is the study of
heredity
• Some examples of traits are:
eye color, height, nose shape,
etc!
• Monk from Austria in
mid-1800’s
• Cross-pollinated pea
plants to see what
traits were inherited
by following
generations
• Importance of his
experiments not
recognized until
1900’s
• Now known as Father
of Genetics
Steps of
Mendel's
Experiment
Mendel crossed them
• Gametes- male and female sex
cells
• Fertilization - the uniting of
male and female gametes
• Cross - combining gametes from
parents with different traits
Each organism has two
ALLELES for each TRAIT
• Alleles - different forms of
the same gene
• Genes - located on
chromosomes, they control
how an organism develops
• Purebred - offspring of many
generations with the same
trait (both alleles the SAME)
Mendel’s Experiment
• P (parent)
generation- He first
crossed two purebred
pea plants – one that
had two alleles for
being TALL, one that
had two alleles for
being SHORT
• F1 (first filial)
offspring- They were
ALL TALL!!!!
• F2 (second filial)
offspring- About ¼ of
this generation were
SHORT!
Rule of Dominance
• The trait that is observed in
the offspring is the dominant
trait (uppercase)
• The trait that disappears in
the offspring is the
recessive trait (lowercase)
COMBINATIONS
If the alleles for Then the trait
Example - trait will
a trait are:
will show up as: be ARCHED (e) or
STRAIGHT (E)
eyebrows
TT or tt
T or t
(purebred dominant or
purebred recessive)
Tt
(HYBRID- one
dominant and one
recessive allele)
T
EE = straight
eyebrows
ee = arched
eyebrows
Ee = straight
eyebrows