3vt monohybrid crosses

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Slide 1: Diapositive
BiologieMiddelbare schoolvwoLeerjaar 3

Cette leçon contient 36 diapositives, avec quiz interactifs et diapositives de texte.

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Slide 1 - Diapositive

Recap
Each individual contains 23 pairs of chromosomes.
You receive one from your mother and one from your father.
Every chromosome contains many genes also called alleles 
The alleles from your mother and father together determine the hereditary characteristics

Slide 2 - Diapositive

Homozygous and heterozygous
Each individual contains two identical or two non-identical alleles.


Two identical alleles: homozygous
Two non-identical alleles: heterozygous




Slide 3 - Diapositive

Dominant and recessive
In a heterozygous indivual only one allele can be expressed in the phenotype: this is called the dominant allele. 
The stronger allele

The other allele is called the recessive allele. This allele is only expressed in the phenotype when it comes in a pair.

Slide 4 - Diapositive

Genotype
In genetics the genotype is expressed in capital and small letters:

AA: homozygous dominant
aa: homozygous recessive
Aa: heterozygous

Slide 5 - Diapositive

Exercise 1
A father has brown eyes. He is heterozygous for eye colour. Mother has blue eyes. The gene for brown eyes is dominant.

a. Is mother homozygous or heterozygous for eye colour?
   
   b. Two children are born. Child 1 has brown eyes and child 2 has blue eyes. Show this in a cross. Use the letters B and b

Slide 6 - Diapositive

P
P
genotype
phenotype
F1
sex cells
possibilities for F1:

Slide 7 - Diapositive

Father has brown eyes. 

Slide 8 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
brown eyes
possibilities for F1:

Slide 9 - Diapositive

Mother has blue eyes. 

Slide 10 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
brown eyes
blue eyes
possibilities for F1:

Slide 11 - Diapositive

A father has brown eyes. He is heterozygous for eye colour. Mother has blue eyes. The gene for brown eyes is dominant.


Slide 12 - Diapositive

What is the genotype of the father?
A
BB
B
Bb
C
bb

Slide 13 - Quiz

What is the genotype of the mother?
A
BB
B
Bb

Slide 14 - Quiz

P
P
genotype:
phenotype:
F1
sex cells:
brown eyes
blue eyes
bb                             Bb
possibilities for F1:

Slide 15 - Diapositive

A father has brown eyes. He is heterozygous for eye colour. Mother has blue eyes. The gene for brown eyes is dominant.

a. Is mother homozygous or heterozygous for eye colour?
  

Slide 16 - Diapositive

Is mother homozygous or heterozygous for eye colour?
A
homozygous
B
heterozygous

Slide 17 - Quiz

P
P
genotype:
phenotype:
F1
sex cells:
brown eyes
blue eyes
bb                             Bb
possibilities for F1:
And now the sex cells are made...

Slide 18 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:

Slide 19 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:
What eye colour do the children (F1) have?

Slide 20 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
b
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:
spermcells 
egg cells

Slide 21 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
Bb
b
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:

Slide 22 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
Bb
bb
b
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:

Slide 23 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
Bb
bb
b
Bb
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:

Slide 24 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
Bb
bb
b
Bb
bb
brown eyes
blue eyes
bb                             Bb
b
b
b
B
possibilities for F1:

Slide 25 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
Bb
bb
b
Bb
bb
brown eyes
blue eyes
bb                             Bb
b
b
b
B
genotype        
  • 2x Bb (50%) 
  • 2x bb (50%) 
possibilities for F1:

Slide 26 - Diapositive

P
P
genotype:
phenotype:
F1
sex cells:
B
b
b
Bb
bb
b
Bb
bb
brown eyes
blue eyes
bb                             Bb
b
b
b
B
genotype        
  • 2x Bb (50%) 
  • 2x bb (50%) 
phenotype
  • brown eyes
  • blue eyes
possibilities for F1:

Slide 27 - Diapositive

Exercise 2
A man is right handed. He has two identical alleles for this trait. A woman is right-handed as well, but she is heterozygous.

When the man and woman will have a baby. What is the chance that the baby has the same phenotype as his/her parents.

Slide 28 - Diapositive

P
P
genotype
phenotype
F1
sex cells
possibilities for F1:

Slide 29 - Diapositive

Add a photo of your cross

Slide 30 - Question ouverte

Slide 31 - Diapositive

Exercise 3
Two black guinea pigs that are both heterozygous for fur colour get offspring.  The black allele is dominant and the white allele is recessive

What can be the genotypes of the offspring?
What can be the phenotypes of the offspring? 
Give also the proportions in percentages.

Slide 32 - Diapositive

P
P
genotype
phenotype
F1
sex cells
possibilities for F1:

Slide 33 - Diapositive

Add a photo of your cross

Slide 34 - Question ouverte

Slide 35 - Diapositive

A family tree

What phenotype is dominant?

Slide 36 - Diapositive