5.4 Inheritance

• Biologie
• Middelbare school
• havo, vwo
• Leerjaar 3

5.4 Inheritance

Allele =

Alleles =

NOTE.

 • Dominant allele = 

 • Recessive allele = 

What is an allele?

An allele is a different form of a gene

Why do you have two alleles for each gene?

Because you have two chromosomes with the same gene (one from mom, one from dad)

Oliver says: 'all humans have the same genes, but not the same alleles'. Charley says: 'all humans have the same alleles, but not the same genes'. Who is right?

1. Oliver
2. Charley
3. They both are
4. They are both wrong

Is it a gene or an allele?

GENE

ALLELE

skin colour

curly hair

flower colour

blue eyes

blood type

type A blood

colour-blindness

hair type

short wings in a fruit fly

5.4 INHERITANCE

• You describe, explain, recognize and apply the following terms; homozygous, heterozygous, gene, alleles, dominant, recessive, carrier, P-generation, F1-generation, F2-generation.   
• You can use your knowledge about inheritance and a Punnet-square to predict the probabilities of offspring having a given genotype or phenotype.
  
• You can explain that you have two alleles for each gene.
  
• You can use and recognize the notation for homozygous dominant (AA) /recessive (aa) and heterozygous genotypes (Aa).  

NOTE. INHERITANCE (terminology)

Heterozygous = 2 different alleles Aa

Homozygous= 2 same alleles 

Homozygous dominant= 2 dominant alleles AA

Homozygous recessive= 2 recessive alleles aa

Homozygous dominant:

1. RR
2. Rr
3. rr

Some fruit flies have curly wings instead of normal wings (see the pictures below). Answer the questions using the letter R for normal wings and r for curly wings:

normal wings                 curly wings

a. Which is the dominant allele? Give the letter and the characteristic. R normal wings

b. Which is the recessive allele? Give the letter and the characteristic. r curly wings

c. What is the genotype of a fruit fly that is homozygous for normal wings? RR

d. What is the genotype of a fruit fly that is homozygous for curly wings? rr

e. What is the genotype of a fruit fly that is heterozygous? Rr

f. Which two genotypes will result in the ‘normal wings’ phenotype? RR and Rr

Some fruit flies have curly wings instead of normal wings (see the pictures below). Answer the questions using the letter R for normal wings and r for curly wings:

normal wings                 curly wings

g. Can a fruit fly with normal wings have a homozygous genotype? Yes RR

h. Can a fruit fly with normal wings have a heterozygous genotype? Yes Rr

i. Can a fruit fly with curly wings have a homozygous genotype? Yes rr

j. Can a fruit fly with curly wings have a heterozygous genotype? Explain your thinking. No, because when the dominant allele is present, the fenotype will be dominant

CALCULATE THE CHANCE. 

  

Let's practice! A guinea pig is heterozygous and has blue fur. This guinea pig mates with a guinea pig with yellow fur. Use a punnet square to determine the probability of one of their offspring having blue fur.

CALCULATE THE CHANCE. 

  

Let's practice! A guinea pig is heterozygous and has blue fur. This guinea pig mates with a guinea pig with yellow fur. Use a punnet square to determine the probability of one of their offspring having blue fur.

Dominant allele = blue fur

Recessive allele = yellow fur

genotype blue pig = Bb

genotype yellow pig = bb

CALCULATE THE CHANCE. 

  

Let's practice! A guinea pig is heterozygous and has blue fur. This guinea pig mates with a guinea pig with yellow fur. Use a punnet square to determine the probability of one of their offspring having blue fur.

F1 genotypes: Bb 50%  bb 50%

F1 phenotypes: blue 50%

                         yellow 50%

Homework

21, 22 and 23