1. GENETICS NOTES NAME: ___________________________
• Gregor _________________—the father of genetics
• Genetics—the scientific study of ____________
• Heredity—the passing of traits from parents to ________________
MENDEL’S PEAS
Mendel could learn a lot from peas because:
• Pea plants have many traits that exist in only _______ forms such as ______ or short plants, but
no medium plants.
• Peas produce a large number of offspring (kids) in each generation
HOW CAN PEA PLANTS REPRODUCE?
Normally pea plants self pollinate. This means that pollen from the stamen of a plant enters the pistil of
the ___________ plant.
1. Self-pollination example: Pollen located on the stamen moves to pistil
Of the same plant
Mendel cross pollinated plants. This means that he took pollen from a plant and rubbed it on the pistil
of a different plant from which the stamens had been removed (so they couldn’t self pollinate).
2. Cross Pollination example: To visualize cross pollination, notice how pollen moves from the
stamen on plant A to the pistol on plant B.
• ___________________—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 a _________. That would be like a pound puppy.
MENDEL’S EXPERIMENT: WHAT DID MENDEL DO, EXACTLY?
• In his first experiment Mendel crossed purebred tall plants (they only have _______ genes)
with purebred short plants (that only have _______ genes).

2. • Filial (_______) generation—name given to the offspring of the first cross.
Results of F2
• Mendel allowed the F1 plants to __________-pollinate.
• He found that the F2 plants were a mix of tall and short plants in a ration of ____tall to ¼ short.
You could also look at it like this:
_____generation
(cross pollinated)
____ generation  Why were all the kiddos tall here?
(self-pollinated)
All tall
____ generation  Where did the little one come
¾ tall and ¼ short from? His parents were both tall?
TRAITS MENDEL STUDIED IN PEA
PLANTS:
Mendel also studied _____traits of pea plants:
They were : Seed shape, seed color, seed coat
color, pod shape, flower position, flower
color, and stem height.
DOMINENT AND RECESSIVE
ALLELES
• ____________—the factors that control each trait exist in pairs.
– ____________ parent—contributes one factor
– ____________ parent—contributes one factor
– Together these make a pair
• ____________—are the factors that control traits.
• Genes consist of pairs of ______________. One that comes from the mother parent and one
that comes from the father parent.
• Alleles—the different forms of a __________ (such as tall or short, wrinkled or smooth).
• Dominant allele—one whose trait always ____________ 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 __________ present.

3. Practice: Write down the following answers. Will the baby show dominant or recessive traits?
dominant dominant
recessive dominant
recessive recessive
• The only time the green box (or ______________ allele) could show up is when a black box
(or dominant allele) was not present.
• This will lead us into ____________ squares.
PUNNETT SQUARES
• So Mendel started out with 2 purebred plants. One
was __________ and one was ___________
• __________ T means “tall allele”, ________ “t”
means “short allel”
• But, each of those two plants (tall one and short
one) has 2 alleles. They received one from their
___________ and one from their __________.
• Options are T(_______) or t(__________)
• Tall plant was TT –____________
• Short plant was tt--_____________
• You take this information and put it in a Punnett
Square.
But what does it all mean?
The results represent the 4 possible __________; which is the ____________ of children’s height.
PROBABILITY
Probability--The likelihood that a particular event will ________________.
• Tossing a coin—landing head us is ?
• The __________ the sample size (more ________ of a coin), the closer the actual results
_____________ by probability.
• What about children. What is the likelihood that a woman would have a boy instead of a
girl?
Mendel used probability in genetics.
• Mendel was the first person to realize that probability can be used to predict the results of
genetic ______________.
• In other words he could use probability to “_________” that all the offspring of the first
generation would be tall… without even ____________ them.

4. In a cross between 2 hybrid tall plants (_____x ____), the probability of offspring having the dominant
characteristic is ______% (or 3 out of 4 or ¾) while the probability of the offspring having the
recessive characteristic is ________% (or 1 out of 4 or ¼)
In a cross between two purebred plants (TT x tt), the probability of the offspring having the dominant
characteristics is 100% (or 4 out of 4 which is the same as 4/4)
PHENOTYPE and GENOTYPE
• _______________—The physical appearance of the offspring. (ex. Tall or short)
• _______________—The genetic makeup or allele combination of the offspring.
– ____________ (purebred)—2 of the same alleles
• TT or tt
– ____________ (hybrid)—2 different alleles
• Tt or tT which are the same thing.
What are the genotypes present above ?___________________________________________________
• If there is one dominant (capital letter) trait, then that is the physical characteristic that shows
up.
• Recessive traits only show up if there are no dominant traits present.
What are the phenotypes present above? __________________________________________________

5. CODOMINANCE
• Alleles are neither ___________ nor ___________. Neither allele is covered up. Both ____ up.
• Write them as capital letters with superscripts. (F or F = black or white feathers).
• This means that F F heterozygous chickens have _______ black and white feathers.
• Red hair and White hair are co dominant in cattle. Heterozygous ( H H ) cattle have red hairs
and white hairs. They are called roan.
Yellow (yy) is recessive, Y is green, y is yellow
Green (YY) is dominant (second generation)
What would be heterozygous/ hybrid?_____ How many children are green? _______
How many purebred children did you get?_____ How many children are yellow? ______
How many hybrid children did you get? _____
R=round, r=wrinkled : Y=yellow, y=green
Use the information above to draw and color in the large punnett square. You may talk in groups to try
and decide.