Watch This:
 http://ed.ted.com/lessons/how-mendel-s-pea-plants-
helped-us-understand-genetics-hortensia-jimenezdiaz
Tossing Coins
 If you toss a coin, what is the probability of getting
heads? Tails? If you toss a coin 10 times, how many
heads and how many tails would you expect to get?
Working with a partner, have one person toss a coin
ten times while the other person tallies the results on a
sheet of paper. Then, switch tasks to produce a
separate tally of the second set of 10 tosses.
Vocabulary
 Genetics:
 the scientific study of ____________
 Allele one of a number of _____ forms of a gene
 Trait Specific __________ that varies from one individual to
another
Vocabulary
 Phenotype _____ characteristics
of an organism
 Genotype _______ makeup of an
organism
Bb
Vocabulary
 Homozygous term used to refer to an
organism that has two
______ alleles for a
particular trait.
 Heterozygous term used to refer to an
organism that has two
______ alleles for the
same trait.
Vocabulary
 Hybrid
- offspring of ________ between parents with
different traits
 True-breeding- term used to describe organisms that produce
offspring identical to themselves if allowed to
self-pollinate
Vocabulary
 Probability
- likelihood that a
particular event will
occur.
 Punnett Square
- diagram showing the
gene _________ that
might result from a
genetic cross.
Genetic Notes
1. Genes and Dominance
a. ________ studied different traits with contrasting
characteristics
b. _______- a specific characteristic such as seed color or
plant height that varies from one individual to
another.
c. Hybrids- Offspring of parent crosses with ______
traits
d. Genes- chemical _______ that determine traits
(height)
e. Alleles- _______ forms of a gene (short or tall)
Genetic Notes
f. Principle of _______: Alleles can be dominant or
recessive
i. Dominant: trait is always seen
Ii. Recessive: trait is seen if dominant is not present
Genetics Notes
2. Genetics & Probability
a.
b.
Probability- the
likelihood that a
particular event will
occur
The principles of
probability can be used
to predict the outcomes
of genetic crosses
3.Punnett Squares
a. Punnett Square is a
diagram used to
determine the gene
combinations that
might result from a
genetic cross (the
offspring from two
chosen parents)
b. Letters in the squares
represent alleles
Capital letters for
_________ alleles
Ii. Lowercase letters
for
________alleles
i.
Homozygousorganisms that have
two identical alleles
for a particular trait
(TT or tt) : are
_______ _______
d. Heterozygousorganisms that have
two different alleles
for a particular trait
(Tt) : are _______
c.
TT
Tt
e.
Offspring can have the same ________ but
different ________
i.
Phenotype- physical characteristics
ii. Genotype- genetic makeup
4. Probability and Segregation
Mendels results showed
i. Homozygous dominant
= ¼ (25%)
ii. Heterozygous = ½
(50%)
iii. Homozygous recessive
= ¼ (25%)
b. The ratio of tall plants to
short is 3:1
c. Due to the 75% dominant
traits showing and 25%
recessive traits showing,
Mendel concluded that
segregation occurs
a.
Review

What is
probability?


The likelihood that a
particular event will
occur.
What is a
punnett square?

A diagram that shows
all gene combinations
that might result
from a genetic cross.
Review

How are the principles
of probability used to
predict the outcomes
of genetic crosses?

The way which the alleles
segregate is random and
probability allows the
calculation of the likelihood
that a particular allele
combination will occur in
offspring.
Review
 What are dominant and recessive alleles?
 Dominant allele: allele whose from of a trait always show
up in an organism if the dominant allele is present
 Recessive allele: allele whose form of a trait shows up only
when the dominant allele is not present.