12.1 Passing on characteristics

• Biologie
• Middelbare school
• havo
• Leerjaar 3

12.1 Passing on characteristics

Learning objective

You will learn where you get your characteristics from and how you can pass them on.

There are a lot of videos in the shared version of this LessonUp. 

Genotype/Phenotype, Alleles and Genes, Homozygous/Heterozygous, Dominant/Recessive alleles

Where Duke's blue eyes come from

Passing on characteristics

-Genes have several variants.

e.g. 1 allele for brown, 1 allele for blue.

 The genotype always contains two alleles per trait (one from mother and one from father). 

Homozygous and heterozygous.

Homozygous: if two alleles for the trait are the same 

(for example for eye color: both blue)

Heterozygous: if the two alleles are different (e.g. blue/brown)

Passing on alleles

Dominant and recessive

Dominant: The stronger allele for a characteristic.

Recessive = the suppressed allele for a characteristic.

Where Duke's blue eyes come from

Denoting genotypes

*Dominant alleles are indicated with a capital letter

*Recessive alleles are indicated with a lower case letter.

Tip: Always choose a letter where the capital letter does not resemble the small letter.

Denoting genotypes

2 alleles for each trait.

Therefore: a genotype 'code' consists of 2 letters.

BB means homozygous dominant

Bb means heterozygous

bb means homozygous recessive

What will the offspring look like?

Based on the genotype of parents, you can make a prediction about the genotype of the offspring.


(Crossing = two parents producing offspring together)

What will the offspring look like?

Based on the genotype of parents, you can make a prediction about the genotype of the offspring.


(Crossing = two parents producing offspring together)

Hoe maak ik een kruisingsschema?

What?	Read: 12.1 Make: assignments 2, 4-8, 10, 13-17
How?	In your book. You may consult with your neighbour in a whisper.
Help?	Raise your hand.
Time?	10 minutes
Finished?	Read: how does DNA determine your hereditary characteristics? Make 25 and 27
Proceeds	You have finished your homework! Well done!

• You will learn where you get your characteristics from and how you can pass them on.