Select a number from the existing
numbers
3
2
1
6
5
4
9
8
7
What type of organisms only reproduce
asexually?
A. bacteria
B. protists
C. plants
D. simple animals
Name the person known as the father of genetics.
A. Felix Mendelssohn
B. Gregor Mendel
C. Dr. Reginald Punnett
D. Albert Einstein
Which pair of alleles is heterozygous?
A. RR
B. Rr
C. rr
D. yR
Study the figures and answer
How many cells are produced in
the mitosis?
2. How many cells are produced
in the meiosis?
Mitosis= 2cells
Meiosis = 4gamets
What is this process called?
A. fertilization
B. gamete formation
C. inheritance
D. reproduction
Segments of DNA that control the production
of proteins are called _______.
A. chromatids
B. chromosomes
C. genes
D. traits
What is the name for different forms of a
single gene that are passed from generation
to generation?
A. alleles
B. genotypes
C. phenotypes
D. traits
To which step in this
process does the law of
segregation apply?
A. grows into plant
B. gamete formation
C. fertilization
D. seed development
Try again
Is Varies
questions
Duration of activity: 4 min
STARTER
Chapter 4
Section 1:
Meiosis
Section 2:
Mendelian Genetics
Section 3:
Genetic linkage and
chromosomes
diversity
Sexual Reproduction and
Genetics
Today we will talk about
Mendelian
Genetics
4.2 Mendelian Genetics
What do I know about?
What do I want to know about ?
How can I find out?
What you learned about?
What action will I take?
What new questions do I have?
Review Vocabulary
segregation:
the separation of allelic
genes that typically
occurs during meiosis
Sexual Reproduction and Genetics
Today’s vocabulary item
genetics
phenotype
allele
dominant
recessive
law of segregation
hybrid
law of independent
homozygous
heterozygous
genotype
assortment
4.2 Mendelic Inheristance
) Lesson Objectives (
Explain the significance of Mendel’s experiments to
the study of genetics
Summarize the law of segregation and law of
independent assortment.
Predict the possible offspring from a cross using a
Punnett square.
Real world reading link
There are many different breeds of
dogs
Labrador retrievers
dachshunds
German shepherd
You might like a certain breed
of dog because of its height,
coat color, and general
appearance.
Poodles
how genetic traits are passed on to the
next generation.
Section 2
Mendelic Inheristance
Mendel explained how a
dominant allele can mask the
presence of a recessive allele.
How Genetics Began
Gregor Mendel
father of genetics
Pea plants
Pea plants are:
1.Easy to grow
2.Many are truebreeding, Produce
offspring with only
one form of a trait.
3. Reproduce by
self-fertilization
Mendel studied seven different traits.
 Seed or pea color
 Flower color
 Seed pod color
 Seed shape or texture
 Seed pod shape
 Stem length
 Flower position
F2 generation plants from these
crosses also showed a 3:1 ratio.
Strategy is
Think
discuss with your partner
Participate
You have two
pictures, which
one is self
pollination, and
the cross
pollination?
Duration of activity: 1 min
cross pollination
Self pollination
Transferring a male gamete
from the flower of one pea
plant to the female
reproductive organ in a
flower of another pea plant.
occurs when a male gamete
within a flower combines with
a female gamete in the same
flower.
cross pollination
Self pollination
What is heredity?
The passing on of characteristics
(traits) from parents to offspring
What is Genetics ?
is the study of heredity
parent generation
Male
gamete
Female
gamete
(
p)
true-breeding green-seed true-breeding yellow-seed
( cross pollination)
yellow-seed First filial generation
(F1)
( self pollination)
Second filial generation
green-seed
2001
Ratio
1
:
yellow-seed
6022
3
(F2)
Mendel removed the male organs
from the flower of the
yellow-seed plant, Why???
To prevent self fertilization
Infer why it is important that mendel’s
experiments used to true breeding plant?
The use of true-breeding
plants allowed Mendel
to easily segregate the genes
passed from generation to
generation
Alleles
•Each organism has
two alleles for
each trait
•Alleles - different
forms of the same
gene
•Genes - located on
chromosomes, they
control how an
organism develops
allele
 An alternative form of a
single gene passed from
generation to generation
Phenotype & Genotype
An organism’s allele pairs
Genotype
Phenotype
The observable characteristic or
outward expression of an allele
pair
yellow-seed
Phenotype & Genotype
•Phenotype - the way an organism
looks
• Example - red hair or brown hair
•genotype - the gene combination
of an organism
• AA or Aa or aa
Heterozygous & Homozygous
•Heterozygous - if the two alleles for
a trait are different (Aa)
•Homozygous - if the two alleles for
a trait are the same (AA or aa)
WW - Homozygous dominant
Ww – Heterozygous( hybrid)
ww - Homozygous recessive
Write
Heterozygous or Homozygous???
BB
Bb
bb
Male
gamete
Phenotype
Genotype
Female
gamete
green-seed
yy
Phenotype
parent generation
(
p)
yellow-seed
YY
yellow-seed First filial generation
Genotype
(F1)
Yy
Second filial generation
Ratio
green-seed
2001
1
:
yellow-seed
6022
3
(F2)
Look at the shape, write the recessive trait and
dominant trait
yellow-seed Dominant
green-seed recessive
Comment on your
work
Explain the
significance of
Mendel’s
experiments
to the study of
genetics
First filial generation
(F1)
( self pollination)
Y
Y
y
y
Second filial generation
(F2)
Phenotype
yellow-seed
Genotype
Yy
Ratio
Phenotype
Ratio
2
yellow-seed green-seed
yy
YY
:
1
:
1
yellow-seed
green-seed
3
1
Why the seeds in the F1 generation were all
yellow?
The yellow seed was the
dominant form of the trait.
All the seeds in the F1
generation received one
copy of the dominant
gene.
Mendel’s Law of Segregation
Two alleles for each trait separate during meiosis
During fertilization, two alleles for that trait unite.
Heterozygous organisms are called hybrids.
Monohybrid Cross
A cross that
involves hybrids
for a single trait
(seed color)
green-seed yellow-seed
Punnett Squares-Monohybrid Cross
Predict the
possible
offspring of a
cross
between two
known
genotypes
Comment on your
work
Predict the
possible
offspring from
a cross using a
Punnett
square.
Dihybrid Cross two traits
(seed color)
(seed form)
yellow-seed
round-seed
green-seed
wrinkle-seed
Look at the shape, write the recessive trait and
dominant trait
yellow-seed
round-seed
Dominant
green-seed
wrinkle-seed
recessive
Look at the shape, write the Genotype
yellow, round-seed pea plants
YY RR
green, wrinkle-seed pea plants
yyrr
Dihybrid Cross
Sexual Reproduction and Genetics
The simultaneous inheritance of two
or more traits in the same plant
yellow, round-seed pea plants
YY RR
green, wrinkle-seed pea plants
yyrr
Dihybrids are heterozygous for both
traits.
parent generation
(
p)
yyrr
YY RR
( cross pollination)
First filial generation
(F1)
( self pollination)
( Gametes)
Yy
YyRr
Rr
Punnett square—Dihybrid cross
 Four types of
alleles from the
male gametes and
four types of
alleles from the
female gametes
can be produced.
He counted and recorded four different
Phenotypes
315 yellow round
108 green round
101 yellow wrinkled
32 green wrinkled
Ratio 9:3:3:1.
Genotypes:
YYRR
YYRr
Yyrr
YyRR
YyRr
Yyrr
yyRr
yyRR
yyrr
Punnett Square—
Dihybrid Cross
 The resulting
phenotypic
ratio is 9:3:3:1.
law of independent assortment
 random distribution of alleles occurs during
gamete formation.
Genes on separate chromosomes sort
independently during meiosis.
 Each allele combination is equally likely to
occur.
Evaluate How can the random
distribution of alleles result in a
predictable ratio?
Because there is an equal chance that each pair
of alleles can randomly combine with each
other, the outcome of a large sample size will be
a predictable ratio
Predict How
many possible
gamete types are
produce?
Four
Comment on your
work
Summarize
the law of
segregation
and law of
independent
assortment.