CHAPTER 12
GENETICS
March 8 and 10: Introduction to Genetics/
Further exploring gene expression
At Home learners: Take the Check-In survey
ALL STUDENTS: Write a hypothesis to the question posed in the schoology
discussion: “How Did Noelle Get These Parakeets?”
i
Write a hypothesis for the chapter mystery
problem.
Write a hypothesis for the chapter mystery
problem.
March 10, 2021
If you’re remote: Fill in the check in form
ALL STUDENTS: Fill in the Dominant and Recessive Trait
survey in the week 9 folder in schoology.
Remote Learners
●
●
●
●
Finish your assessment from last week
Complete the Note Taking Guide for 12.1
Work in breakout rooms if you choose.
Leave when you’re finished.
March 16, 2021
THE WORK OF
GREGOR MENDEL
● CHECK IN IS DIFFERENT! I’m just
going to be checking in with you as
you arrive.
● Make sure you’ve got a coin with
you :)
● Open the 12.1 note taking guide
you completed last week (it should
be in your google docs)
● Open the “Probability and
Heredity” Note taking guide in
Notability.
MODEL SYSTEMS
• Mendel used pea plants as a model system to study
genetics.
• Discuss and write some reasons why peas were better
than using other common agricultural organisms.
THE ROLE OF
FERTILIZATION
• How are pea plants typically
fertilized?
• How did Mendel modify how they
were fertilized?
GENES AND ALLELES
• Traits are controlled by
genes
• Genes often have two or
more alleles
• Which traits did Mendel
study? What were the alleles
for those traits?
Trait
Alleles
Dominant
trait
Recessive
trait
Seed shape
Round and
Wrinkled
Round
Wrinkled
DOMINANT AND RECESSIVE ALLELES
An organism with a recessive allele will only express
that trait if the dominant allele is not present.
• Of the traits that Mendel studied which alleles were
dominant and which were recessive?
Trait
Alleles
Dominant
trait
Recessive
trait
Seed shape
Round and
Wrinkled
Round
Wrinkled
Seed Color
Yellow and
Green
Seed Coat
Gray and
White
Pod Shape
Smooth and
constricted
Pod Color
Green and
yellow
Flower
Position
Axial and
terminal
Plant Height
Tall and short
Trait
Alleles
Dominant
trait
Recessive
trait
Seed shape
Round and
Wrinkled
Round
Wrinkled
Seed Color
Yellow and
Green
Yellow
Green
Seed Coat
Gray and
White
Gray
White
Pod Shape
Smooth and
constricted
Smooth
Constricted
Pod Color
Green and
yellow
Green
Yellow
Flower
Position
Axial and
terminal
Axial
Terminal
Plant Height
Tall and short
Tall
Short
DOMINANT AND RECESSIVE TRAITS IN HUMANS
• Look at the class data. Can you infer which traits are
dominant and which are recessive?
DOMINANT AND RECESSIVE TRAITS
• KEY IDEA: Dominant does
not mean “common”.
• Some forms of Polydactyly
(having multiple fingers or
toes) is actually a dominant
trait, although rare in the
population.
• Why do you think some
recessive traits are more
common in the population?
SEGREGATION
•
Describe each generation
below.
• P generation:
• F1 generation:
• F2 generation:
•
What did Mendel conclude
from this?
•
FORMATION OF
GAMETES
• Alleles separate during
gamete formation.
(Gametes are reproductive
cells: egg and sperm)
• Offspring receive one
allele from each parent
CHAPTER 11 LESSON 2
PROBABILITY AND HEREDITY
March 18, 2021
Probability and Heredity
Warm up:
● How many times should your coin be heads if you
flip it 10 times? Type your answer in the chat!
● Attendance: Scale of chihuahuas, how are you?
WHAT ARE THE ODDS?
• What is the probability that your coin will land heads
up?
• Test your hypothesis by flipping your coin 10 times.
•
•
Track your progress using the “FIRST: Single Coin Flip
Class Data Collection Form”
After 10 Flips summarize your data with form
“SECOND: Single Coin Flip Data Summary”
WHAT ARE THE ODDS?
• Write a hypothesis. What is the probability that you
AND your partner will flip:
• both heads?
• heads and a tails?
• both tails?
• At home: Use the chat.
• In person: Share out loud (I’ll put it on the board)
WHAT ARE THE ODDS?
• What is the probability that you AND your partner will
flip:
• heads?
• heads and a tails?
• two tails?
• Test your hypothesis: Use the “THIRD: 2 coin flips
data collection” form
WHAT ARE THE ODDS?
• Flip two coins with a partner (a total of 4 coins flipped)
• What is the probability you and your partner will get
•
heads on one penny, tails on the other and two heads
on your silver coins?
Write a hypothesis: At home use the chat, in person
I’ll call on you.
CHAPTER 11 LESSON 2
PROBABILITY AND HEREDITY
STUDENTS WILL BE ABLE TO
• Appropriately choose symbols to represent alleles
when completing Punnett squares.
• Use Punnett squares to predict possible phenotypes
and genotypes single and dual trait crosses.
TERMS WE WILL USE:
• Define and provide an example of the following
• Homozygous:
• Heterozygous:
• Genotype:
• Phenotype:
CHOOSING SYMBOLS
• Same letter is used for both alleles
• Named after dominant allele
• Dominant allele is capitalized, and recessive is
lowercase.
• Choose appropriate symbols to represent the alleles
for the traits that Mendel studied.
Trait
Alleles
Dominant Recessive
trait symbol trait symbol
Seed shape
Round and
Wrinkled
R
Seed Color
Yellow and
Green
Seed Coat
Gray and
White
Pod Shape
Smooth and
constricted
Pod Color
Green and
yellow
Flower
Position
Axial and
terminal
Plant Height
Tall and short
r
WHAT IS THE PHENOTYPE OF EACH OF THE FOLLOWING PEA
PLANTS FROM MENDEL’S TESTS?
Include if the trait is homozygous or heterozygous
• Rr:
• tt:
• GG:
• Yy:
• AA:
• aa:
PUNNETT SQUARES
B
b
B
BB
Bb
b
Bb
bb
• Alleles from parent 1
• Alleles from parent 2
• Possible genotypes of
offspring
PUNNETT SQUARE PRACTICE
Show a cross between two heterozygous yellow seed
pea plants
•
PUNNETT SQUARE PRACTICE
Show a cross between two heterozygous green pod pea
plants
PUNNETT SQUARE PRACTICE
• Show a cross between a short pea plant and a
heterozygous tall pea plant.
PUNNETT SQUARE PRACTICE
• Show a cross between a short pea plant and a
homozygous tall pea plant.
INDEPENDENT ASSORTMENT
• Mendel: “Does segregation of one pair of alleles affect
another set of alleles?”
• Punnett square predictions
• F1:
• F2:
• Observations:
• Conclusions:
March 22, 2021
Probability and Heredity
Warm up:
● Take out your punnett square practice worksheet.
● Correct it in a different color. (answer key in
schoology)
● Attendance: Scale of Patrick, how are you?
WARM UP
• Take out two different coins: a penny and one other
• If both you and a partner each flip a penny and a
silver coin, what is the probability that you will flip two
heads on your penny and two tails on your silver coin
(nickel/dime/quarter, etc.)?
• Test this hypothesis. A google form has been sent to
you to help.
TWO FACTOR CROSS
●
●
Traits often work in
conjunction with each
other.
Mendel studied seed
appearance
(round/wrinkled and
yellow/green)
TWO FACTOR CROSS
●
●
●
To determine the
probability of getting a
combination of traits, we
need to use a more
complex punnett square
This shows a self
pollinating heterozygous
wrinkled; heterozygous
yellow seed plant.
This “Dihybrid cross”
results in a 9:3:3:1 ratio of
phenotypes.
9/16: Round Yellow
3/16: Round Green
3/16: Wrinkled Yellow
1/16: Wrinkled Green
TWO FACTOR CROSS INSTRUCTIONS
• Determine all combinations of alleles that each parent can pass along
• Use FOIL method to help with this
• Check: You should have two letters above each box. Each should represent
a different trait.
• Copy alleles into boxes.
• Check: All boxes should have 4 letters in them, two of each.
• Keep the same letters together and write capital letters first.
• Use highlighters, markers, or symbols to mark the phenotypes in each box.
• Dihybrid crosses result in a 9:3:3:1 ratio
TWO FACTOR CROSS PRACTICE
• What is the probability of each genotype and
phenotype in a cross between a homozygous round,
green seeded plant and a heterozygous round,
heterozygous yellow seeded plant?
• What is the probability of each genotype and
phenotype in a cross between a heterozygous round,
heterozygous yellow seeded plant and a wrinkled,
green seeded plant?
• What is the probability of each genotype and phenotype in
a cross between a homozygous round, green seeded plant
and a heterozygous round, heterozygous yellow seeded
plant?
Ry
Ry
Ry
Ry
RY
RRYy
RRYy
RRYy
RRYy
Ry
RRyy
RRyy
RRyy
RRyy
rY
RrYy
RrYy
RrYy
RrYy
ry
Rryy
Rryy
Rryy
Rryy
50% round yellow seeds, 50% round green seeds
• What is the probability of each genotype and phenotype in
a cross between a heterozygous round, heterozygous yellow
seeded plant and a wrinkled, green seeded plant?
RY
Ry
rY
ry
ry
RrYy
Rryy
rrYy
rryy
ry
RrYy
Rryy
rrYy
rryy
ry
RrYy
Rryy
rrYy
rryy
ry
RrYy
Rryy
rrYy
rryy
25% round yellow seeds, 25% round green seeds,
25% wrinkled yellow seeds, 25% wrinkled green seeds
March 25, 2021
OTHER PATTERNS OF INHERITANCE
(non Mendelian Genetics)
● Open up the Non Mendelian Genetics note taker in
notability
●
INCOMPLETE
DOMINANCE
• Alleles are neither dominant or
recessive; heterozygous
individuals don’t fully express
either trait
•
Examples:
•
•
Four o’clock flowers
andalusian chickens
• What symbols would you suggest
to communicate this?
INCOMPLETE DOMINANCE
• Predict the probability of each genotype and
phenotype if you cross a pink four o'clock flowered
with another pink four o'clock flower plant
INCOMPLETE DOMINANCE
• Predict the probability of each genotype and
phenotype if you cross a white four o'clock plant with
a pink four o'clock flowered plant
CODOMINANCE
Both traits are fully
expressed.
Examples:
●
●
●
Erminette chickens
Camelias
Blood type (A and B are
codominant and
produce type AB)
CODOMINANCE: Symbols
Capital letters named after
trait
Superscript for alleles.
Chicken feather Camellia petal
color
color
Blood type
CODOMINANCE
• What is the probability that an erminette chicken
crossed with another erminette chicken will produce
a black chicken?
• A white chicken?
• Another erminette chicken?
MULTIPLE ALLELES
• There’s more than two
possibilities for types of
alleles
• Examples:
• Rabbit fur coat color.
•
Blood type in humans
(antibodies on surface
called
“Immunoglobulin”
CODOMINANCE and MULTIPLE ALLELES
• If a parent who is heterozygous type A
blood has children with someone who
is heterozygous type B, what blood
types could the children have?
CODOMINANCE and MULTIPLE ALLELES
• If a parent who is homozygous type A
blood has children with someone who
is homozygous type B, what blood
types could the children have?
CODOMINANCE and MULTIPLE ALLELES
• If a parent who is type AB blood has
children with someone who is type O
blood, what blood types could the
children have?
POLYGENIC TRAITS
• Many traits are produced by the interaction of many
genes. This often leads to a range or spectrum of
phenotypes.
• Examples:
●
●
●
Eye color of fruit flies
Skin color of humans
Feather color in parakeets
GENES AND THE ENVIRONMENT
• An environmental
conditions affect gene
expression and
phenotype
• Examples:
•
•
Western white
butterflies
Siamese cats
Revisit your hypothesis.
After talking to the pet shop owner, Noelle learned that two genes control feather color. A dominant Y
allele results in the production of a yellow pigment. The dominant B allele controls melanin production.
If the genotype contains at least one Y and one B allele, the offspring will be green. If the genotype
contains two recessive y alleles and at least one dominant B allele, the offspring will be blue. If the
offspring contains two recessive y alleles and two recessive b alleles, the offspring will be white.
● What are the genotypes of each of the 5 birds that Noelle now has? Discuss with your pod.