Transcript 9.1 Mendel rev 13 - Sonoma Valley High School

Mendelian
Genetics
• was a monk
• Studied
mathematics
• Lived in
Austria in the
mid 1800’s
- First to conduct
genetic
experiments
Gregor Mendel
MENDEL’S LEGACY
• Mendel was put in
charge of the
monastery garden,
where he began
his experiments
with plant
genetics.
Mendel studied inherence in pea plants
• Peas are easy
to cross
pollinate.
• Traits easy to
observe.
• Many
generations in
short period
of time.
Traits
studied
•Seed shape, color
•Pod shape, color
•Flower color and position on stem
Hand pollination
• Anthers – male
part of plant the
carries pollen
• Stigma – female
part of plant
• Self pollination –
same flower
• Cross –pollination –
different plant
Mendel’s Experiments
• Mendel selfpollinated
plants until
they bred true:
pure strains
• P generation
(parent)
• F1 generation –
1st cross
• F2 generation 2nd cross
The short trait disappeared in the F1
generation, but reappeared in the F2
Mendel’s Conclusions
• A pair of “factors”
determines a trait.
(alleles)
• Dominant: if one
factor is present, the
trait will show (AA or
Aa)
• Recessive: will only
show if dominant
factor is not present
(aa)
Yellow seeds are dominant to
green seeds
Law of segregation
• Alleles for the
same trait are
separated
during gamete
formation.
– Each gamete
has only 1 allele
for each trait
ex: either purple
or white flower
color.
Law of independent assortment
• Alleles for different
traits end up in different
gametes during
meiosis
–traits sort independently
of each other.
Ex: Alleles for seed color and
seed texture are sorted
independently of each other.
(The chromosomes sort
independently)
White board Review
1. What is a
dominant trait?
2. What is the law of
segregation?
3. What is the F1
generation?