Download lesson 8 Medel and probability

Gregor Mendel
the father of
genetics
1822-1884
- studied botany & math
- became a monk
- studies pea plants and inheritance of traits
• Genetics—the scientific study of
heredity
• Heredity—the passing of traits from
parents to offspring
Why Peas?
- many traits that exist in only 2 forms such as
Ex: tall vs short plants, no medium
- produce a large number of offspring
(kids) in each generation
- they can self-pollinate
or be cross pollinated
What is self-pollination?
• pollen from the stamen of a plant
enters the pistil of the same plant.
What is Cross-Pollination?
• Mendel took pollen from a plant and rubbed
it on the pistil of a different plant (with no
stamens)
Cross Pollination diagram
• Purebred—always produces offspring
with the same form of a trait as the parent.
• Ex. Purebred dogs. Like Cocker spaniels,
golden retrievers, Poodles.
The opposite is hybrid.
This would be a pound
puppy
Mendel’s Experiments
In his first experiment Mendel
crossed purebred tall plants
(they only have tall genes) with
purebred short plants (that only
have short genes).
Filial (F1) generation—name
given to the offspring of the first
cross.
Mendel’s Experiments
Mendel cross-pollinated purebred tall plants
with purebred short plants and got….
?
Tall plant (breed) short plants
P generation (think “parents”)
F1 generation
What he found...
All TALL pea plants in the F1 generation….
P generation (think “parents”)
F1 generation
He concluded
• Tall plants must DOMINATE over short
plants
• He repeated the experiment switching
which plant donated the POLLEN
• Same results
• He repeated the experiment with several
other traits
11
Traits Mendel studied in Pea Plants
• Mendel also studied _7_ traits of pea plants: They were :
Seed shape, seed color, seed coat color, pod shape, flower
position, flower color, and stem height.
Dominant and Recessive Alleles
• Alleles—the different forms of a gene (such
as tall or short, wrinkled or smooth).
• Dominant allele—one whose trait always
shows up when the allele is present.
• Recessive allele—is masked (or covered
up) when the dominant allele is present.
Recessive alleles only show up if a
dominant allele is not present.
EXAMPLES
recessive
dominant
Recessive is the green box and dominant is the black box. Each
of your parents has a pair of alleles that they can share. If they
only give one… answer the following questions.
dominant
dominant
?
recessive
dominant
?
recessive
recessive
?
EXAMPLES
recessive
dominant
Recessive is the green box and dominant is the black box. Each
of your parents has a pair of alleles that they can share. If they
only give one… answer the following questions.
dominant
?
dominant
dominant
recessive
dominant
?
recessive
recessive
?
EXAMPLES
recessive
dominant
Recessive is the green box and dominant is the black box. Each
of your parents has a pair of alleles that they can share. If they
only give one… answer the following questions.
dominant
dominant
dominant
?
recessive
dominant
?
dominant
recessive
recessive
?
EXAMPLES
recessive
dominant
Recessive is the green box and dominant is the black box. Each
of your parents has a pair of alleles that they can share. If they
only give one… answer the following questions.
dominant
dominant
dominant
?
recessive
dominant
?
dominant
recessive
recessive
?
recessive
Notice
• The only time the green box (or recessive
allele) could show up is when a black box
(or dominant allele) was not present.
• This will lead us into punnett squares.
recessive
recessive
recessive
Activities for them
• Pea Soup
• Animated Cross
Future activities
•
•
•
•
•
Princess and Wrinkled Pea, Biologica
Dragon Genetics, Biologica
Mendel’s Peas, Biologica
Cloning, Brain Pop
DNA, Brain Pop (digestion, avian flu too)
Resources for me
• Serendipity Labs
• Holy moly animations