Mendel cultivated pea plants and tested some plants He found that true-breeding plants make offspring retained traits of the Parents every time. Experimental data, Mendel deduced that an organism has two genes ) for each inherited characteristic
Site of
Gregor
Mendel’s
experimental
garden in the
Czech
Republic
Mendel’s peas • Mendel looked at seven traits
or characteristics of pea plants:
1. Flower color purple or white
2. Flower position axial or terminal
3. Stem length Tall or Dwarf
4 . Seed shape round or wrinkled
5. Seed color yellow or green
6. Pod shape inflated or constricted
7. Pod color green or yellow
are used to show the mating of two parents and the possible offspring they can produce.
STEPS:
TT and t t Cross
T T t t
T t
T t
T t
T t
T T
t t
Genotypes: 100% T t
Phenotypes: 100% Tall plants
T T t t
T T
T t
T t
t t
T t
T t
• A heterozygous with a homozygous
T t t t
T
t
t
T t
t t
You can still use the shortcut!
LAW PARENT CROSS OFFSPRING
DOMINANCE TT x tt tall x short
100% Tt Tall
SEGREGATION Tt x Tt tall x tall
75% tall 25% short
RrGg x RrGg round & green
x round & green
9/16 round seeds & green pods
INDEPENDENT ASSORTMENT
3/16 round seeds & yellow pods
3/16 wrinkled seeds & green pods
1/16 wrinkled seeds & yellow pods
and
F1 hybrids have an appearance somewhat in between the phenotypes of the two parental varieties.
Example: snapdragons (flower)
Rr
Rr
Rr Rr
produces the F1 generation
All Rr = pink
• Two alleles are expressed (multiple alleles) in heterozygous individuals.
: blood group
1. type A
2. type B
3. type AB =
4. type O =
= IAIA or IAi
= IBIB or IBi
IAIB
ii
homozygous male Type B (IBIB)
x
heterozygous female Type A (IAi)
IAIB IBi
IAIB IBi
1/2 = IAIB
1/2 = IBi
IB
IA i
IB
IAi IBi
IAi IBi
1/2 = IAi
1/2 = IBi
i
male Type O (ii) x
female type AB (IAIB) IA IB
i
18
If a boy has a blood type O and his sister has blood type AB
boy - type O (ii) X girl - type
IAIB
ii
Parents: genotypes =IAi and IBi phenotypes = A and B
IB
Answer:
IA i
i