Transcript 08.06.04.Punnett.Square.[3.3.simple] - bettinahull2

Heredity
Holt Biology
Chapter 8, pgs. 170-171
By
Bettina Loell-Hull
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Anticipatory Set
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Anticipation Guide:
Biology Standard 3a, (7b)
(phonotype, genotype, heredity and Punnett Square)
Instructions:
Before the lesson, read the questions and circle T or F in the left hand column.
After lesson, re-read the question and circle T or F in the right hand column.
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Before
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T/F
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T/F
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T/F
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T/F
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T/F
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T/F
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T/F
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T/F
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T/F
Questions
A child receives one allele or version of a trait
from each parent.
Some children don’t get their genes from their
parents because they do not look like their
parents.
An allele is a version of a gene for a trait.
The dominant trait is the expressed version of a
gene or the trait that is visible in an individual.
The recessive trait will always show in an
individual.
Genotype refers to the look of an individual.
Phenotype refers to the genetic make-up of an
individual.
If a child has blue eyes and both parents have
brown eyes, the baby was adopted.
The allele for blond hair is dominant.
After
T/F
T/F
T/F
T/F
T/F
T/F
T/F
T/F
T/F
Studying Heredity
Using the Punnett Square
http://www.dailymail.co.uk/news/article-377839/Black-white-twins.html
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Compare and Contrast the Twins
Same parents
1-dark skin (1 or 2
allele(s) for dark skin
2-brown eyes (1 or 2
allele(s) for brown eyes)
1-light skin (2 alleles
for light skin)
Each parent has 1 brown &
1 blue allele for eye color.
Each parent has 1 allele for
light & 1 allele dark skin.
3-brown hair (1 or 2
allele(s) for brown hair)
Each parent has 1 allele for
brown hair & 1 allele for
blond hair.
fraternal twins
2-blue eyes (2 alleles
for blue eyes)
3-blond hair (2 alleles
for blond hair)
Anticipatory Set
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Heredity and Eye Color
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The Punnett Square Calculates the
Possibilities of the Children’s Looks
Father
Mother
B
B BB
b
Bb
b
bb
Bb
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Odds of Dark Hair vs. White Hair
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Homozygous cross and
Heterozygous Cross
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Standard 3a:
• Students know how the genotypes of the
parents may be expressed as phenotypes in
their offspring.
• Students relate the ratios that Mendel
observed in his crosses to his data and to
examples of their own.
Phenotype (F1 generation 100 % = 4/4)
Phenotype (F2 generation 75% to 25% = 3/1)
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1. dominant
2. recessive
3. phenotype
4. genotype
5. monohybrid
cross
6. homozygous
7. heterozygous 8. allele
9. Punnett square
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1. Dominant (adjective)
• Expressed form of the character trait.
• For example the color of a flower
may be purple and not white because
purple is dominant.
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2. Recessive (adjective)
• The trait that is not expressed
when the dominant form of the
trait is present.
Ex.: In this case, the
baby has blue eyes
because she has two
recessive alleles for
blue eyes.
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3 Phenotype (noun)
• A phenotype is a living thing’s appearance or
other detectable characteristic that results from
the living thing’s genotype and the environment.
• For example: the color of a flower or seed
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4 Genotype (noun)
• The entire genetic makeup of
an organism- its DNA
• Or the combination of genes for one specific
trait.
•For example, the
color of the seed pod
is green but the
genetic make-up of it
is yellow and green.
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5-Monohybrid Cross (noun)
• A cross in which each parent displays
a different form of one allele.
• For example: seed color (YY or yy)
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6-Homozygous (adjective)
• Describes an individual that has identical alleles
for a trait on both gametes.
• Example: PP or pp for color of flower.
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7-Heterozygous (adjective)
• Describes an individual that has two
different alleles for a trait.
• For example, a flower may look
purple but has the alleles Pp for
flower color.
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8-Allele (noun)
• An allele is one of the alternative forms of a
gene that determines a characteristic, such as
hair color.
Example: the alleles
for hair color may be
black or blond.
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9-Punnett Square (noun)
• A Punnett square is a
graphic representation
used to predict the
chances that the
offspring will inherit an
allele for a trait.
What are the chances of a
yellow offspring if yellow is
dominant?
100%
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1-Dominant
A-Describes an individual who has two
different alleles for a trait.
2-Recessive
B-graphic representation used to predict
chances of offspring to inherit allele of a trait
C- The trait that is not expressed when the
dominant form of the character is present.
D- Describes individual with identical
alleles for a trait.
3-phenotype
4-genotype
5-monohybrid
cross
6-homozygous
E-the combination of genes for one
7-heterozygous
G- Expressed form of character trait.
8-allele
H-A cross in which each parent displays a
different form of one character trait.
specific trait.
F- a thing’s or person’s appearance
9-punnett square I- one of the alternative forms of a gene.
Solution to Quiz
Video on
Punnett Square
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2
3
4
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9
G
C
F
E
H
D
A
I
B
Home
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Video
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Video on Heredity
How to use the Punnett Square
to Calculate the Odds
of the Phenotype (looks) of Offspring
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Gregor Mendel's Rules of
Heredity—Demonstration of
impact that Parents
Genotype has on
Offspring’s Phenotype
Using Punnett Squares
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What did we learn from the video?
• We learned how to use the Punnett Square to
calculate the odds of a certain phenotype in the
offspring.
• We learned how to create a Monohybrid Cross
1. with homozygous parents
2. with heterozygous parents
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2
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Modeling 1
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Monohybrid Cross –
with Homozygous Bunny Parents
f
F
F f
F
F f
f
F
f
Black is
dominant
F f
Black Fur
4/4=1=100%
White Fur
0/4=0=0%29
Modeling 2
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Monohybrid Cross (one trait) –
with Heterozygous Bunny Parents
F
F
F F
f
F
f
Black is
dominant
Offspring’s Phenotype
f
F f
f f
Black Fur
White Fur
¾ = 75% =.75 ¼ = 25% =.25
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Guided Practice 1
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Monohybrid Cross – with
Homozygous Parents who have
blue eyes and brown eyes.
b
B
B b
B
B b
b
B
b
B b
Brown is
dominant
Offspring’s Phenotype
Brown Eyes Blue Eyes
4/4 =100% =1 0/4=0%=033
Guided Practice 2
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Monohybrid cross –
with Heterozygous Parents
Who both have Brown Eyes.
B
B
B B
b
B b
b
B
b
Brown is
dominant
bb
Offspring’s Phenotype
Brown Eyes
¾ =75% =.75
Blue Eyes
¼ =25% =.25
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Independent Practice 1
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•
•
•
•
•
•
•
Monohybrid cross with homozygous
(BB or bb) parents
Predict the phenotype of the offspring resulting
from a cross of a white haired dog with a black
haired dog.
Make black hair (B) dominant and white hair (b)
recessive.
The white dog is homozygous recessive.
The black dog is homozygous dominant.
Write the gametes that each parent can.
contribute as row and column labels.
What does the offspring look like?
State your answer in %, fraction, and decimals
for each phonotype.
Monohybrid Cross – with
Homozygous Parents (dogs) who have
white fur and black fur.
Black is
dominant
Offspring’s Phenotype
Black Fur,x/4, %, x.xx
White Fur x/4, %, x.xx
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Monohybrid Cross – with
Homozygous Parents (dogs) who have
white fur and black fur.
b
B
B b
B
B b
b
B
b
B b
Black is
dominant
Offspring’s Phenotype
Black Fur
White Fur
4/4 = 100% =1 0/4 =0% =039
Independent Practice 2
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Monohybrid cross with
heterozygous (Bb and Bb) parents
• Predict the phenotype of the offspring of a cross of a
black haired dog with a black haired dog (black hair
is dominant that is why both dogs are black).
• Both dogs are heterozygous for hair color (Bb and
Bb).
• Write the gametes that each parent can contribute
as row and column labels.
• What does the offspring look like?
• State your answer in %, fraction, and decimals for
each phonotype.
Monohybrid Cross – with
Heterozygous Parents (dogs)
who both have black fur.
Black is
dominant
Offspring’s Phenotype
Black Fur,x/4, %, x.xx
White Fur x/4, %, x.xx
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Monohybrid Cross – with
Heterozygous Parents (dogs)
who both have black fur.
B
b
B
B B
B
b
B b
bb
b
Black is
dominant
Offspring’s Phenotype
Black Fur
¾ =75% =.75
White Fur
¼ =25% =.25
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End of Lesson 1
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1
Modeling
Punnett Squares / Monohybrid Cross (1 traits = fur color)
homozygous parents
Phenotype (looks) of offspring
Fraction
Percent
Decimal
heterozygous parents
/4
%
/4
%
.
.
Phenotype (looks) of offspring
/4
%
Fraction
Percent
Decimal
.
/4
%
.
1. Escape
2. Double Click on document to open in word and see
worksheets
Release test question:
Ch
c
Ch
c
Ch Ch Ch c
Chc cc
Chc Produces offspring
that is least likely to
survive.
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Resources
Types of Learners
http://www.chaminade.org/inspire/learnstl.htm
Video on Punnett Square and monohybrid crosses
with homozygous parents and heterozygous
parents.
Gregor Mendel's Rules of Heredity—
Demonstration of impact that Parents Genotype
has on Offspring’s Phenotype Using Punnett
Squares
Holt Biology, chapter 8, pages 170-171
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