You can draw conclusions about the dominance/recessiveness of a particular allele or the genotype of the parents/children from a story.
You can perform simple crosses using a Punnett square to determine the possible genotypes in the offspring of two parents.
You can use Punnett squares to make predictions about the likelihood of a specific genotype or phenotype occurring in the offspring of two parents.
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Slide 1: Diapositive
BiologieMiddelbare schoolhavo, vwoLeerjaar 2
Cette leçon contient 19 diapositives, avec quiz interactifs et diapositives de texte.
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Éléments de cette leçon
Punnet squares
Take off your jacket
Put your things on your desk
Book, notebook, pencil case
Bag on the floor
timer
4:00
Lessongoals
You can draw conclusions about the dominance/recessiveness of a particular allele or the genotype of the parents/children from a story.
You can perform simple crosses using a Punnett square to determine the possible genotypes in the offspring of two parents.
You can use Punnett squares to make predictions about the likelihood of a specific genotype or phenotype occurring in the offspring of two parents.
Slide 1 - Diapositive
Wheel of homework
Go to Lessonup.app and use this code
Reward
Penalty
Slide 2 - Diapositive
A person is heterozygous for his eyecolour. His genotype for this trait is.
A
AA
B
A or a
C
aa
D
Aa
Slide 3 - Quiz
Two parents with blond hair have a kid who has brown hair. The genotype of the kid must be
A
Aa
B
AA
C
aa
Slide 4 - Quiz
Crossings/using punnet squares
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Slide 5 - Diapositive
Example
Question: Two parents have a child with blond hair. The father is homozygous and has brown hair and the mother is homozygous and has blond hair. If these parents have another child, what are the chances that this kid has brown hair?
Do steps 1,2 and 3
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Slide 6 - Diapositive
Example (continued)
Father
Question: Two parents have a child with blond hair. The father is homozygous and has brown hair and the mother is homozygous and has blond hair. If these parents have another child, what are the chances that this kid has brown hair?
Mother
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Make a punnet Square.
Make a table as shown.
Add mother and father (or the names if you know them)
4
Slide 7 - Diapositive
Example (continued)
a
a
A
A
Father
Question: Two parents have a child with blond hair. The father is homozygous and has brown hair and the mother is homozygous and has blond hair. If these parents have another child, what are the chances that this kid has brown hair?
Mother
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Fill in possible alleles for both parents.
You can get these from the genotypes. Just put each letter of the genotype in their own box
5
Slide 8 - Diapositive
Example (continued)
a
a
A
Aa
Aa
A
Aa
Aa
Father
Question: Two parents have a child with blond hair. The father is homozygous and has brown hair and the mother is homozygous and has blond hair. If these parents have another child, what are the chances that this kid has brown hair?
Mother
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Make combinations
Add the letters of the parents together where they meet in the table.
6
Slide 9 - Diapositive
Example (continued)
a
a
A
Aa
Aa
A
Aa
Aa
Father
Question: Two parents have a child with blond hair. The father is homozygous and has brown hair and the mother is homozygous and has blond hair. If these parents have another child, what are the chances that this kid has brown hair?
Mother
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
All four genotypes are heterozygous, they will all have blond hair. The odds for brown hair are 0%
Answer the question
7
Slide 10 - Diapositive
Choose
Pick one:
Want to try on your own? Go practice in silence.
Go to joinmyquiz.com and use the code given.
Need more help to understand crossings? We'll practice more together!
Slide 11 - Diapositive
Example 2
Two parents both have blue eyes, their first child has brown eyes.
What are the chances for their kids to be heterozygous for this trait?
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Slide 12 - Diapositive
Example 2
Two parents both have blue eyes, their first child has brown eyes.
What are the chances for their kids to be heterozygous for this trait?
Answer:
Blue and brown are possible forms of trait eyecolour
Blue must be dominant, making brown recessive
Father and mother are both heterozygous having genotype Aa
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
Slide 13 - Diapositive
Example 2
Two parents both have blue eyes, their first child has brown eyes.
What are the chances for their kids to be heterozygous for this trait?
Answer:
Blue and brown are possible forms of trait eyecolour
Blue must be dominant, making brown recessive
Father and mother are both heterozygous having genotype Aa
>
>
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
A
a
A
a
Mother
Father
Slide 14 - Diapositive
Example 2
Two parents both have blue eyes, their first child has brown eyes.
What are the chances for their kids to be heterozygous for this trait?
Answer:
Blue and brown are possible forms of trait eyecolour
Blue must be dominant, making brown recessive
Father and mother are both heterozygous having genotype Aa
>
>
>
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
A
a
A
AA
Aa
a
Aa
aa
Mother
Father
Slide 15 - Diapositive
Example 2
Two parents both have blue eyes, their first child has brown eyes.
What are the chances for their kids to be heterozygous for this trait?
Answer:
Blue and brown are possible forms of trait eyecolour
Blue must be dominant, making brown recessive
Father and mother are both heterozygous having genotype Aa
>
>
>
2 of the 4 possible genotypes are heterozygous. That
means there is a 50% chance
steps
Follow these steps:
What are the different forms of the trait?
Which form is dominant/recessive?
What are the genotypes and phenotypes of the parents
Make a Punnet square
Fill in possible alleles of parents
Make combinations
Answer the question
A
a
A
AA
Aa
a
Aa
aa
Mother
Father
Slide 16 - Diapositive
Choose
Pick one:
Do you understand? Go practice on your own in silence.
Go to joinmyquiz.com and use the code given.
Need more help understanding crossings? We'll practice more together!