Single traits

• Biologie
• Middelbare school
• havo
• Leerjaar 2,3

Welcome!

Today:

Explanation about inheriting single traits

Answering/discussing excercises 

What are we going to learn today?

We are going to learn:

the difference between genotype and phenotype. 

What genes and alleles are.

How traits are being passed over from generation to generation.

How traits can also skip a generation. 

Chromosomes

Chromosome pair 

Alleles

Both chromosomes in a pair have the same genes, but the variations, alleles, are different. 

Some alleles are dominant (A), when they are present in a gene, they always become visible. Recessive alleles (a), only become visible when there isn't a dominant allele. 

Alleles

For every trait there are at least two alleles present, in every chromosome from the same pair. So you always have 2 letters. When you have two of the same alleles (AA or aa), it is called homozygous. When you have two different alleles (Aa), it is called heterozygous. 

P-generation

Inheriting traits always start at a parent generation (P-generation). You always have to know their genotype about the trait. You always have to write it down as: (genotype parent 1) x (genotype parent 2)

For example: Aa x aa

2 labradors are going to mate. One has a brown fur, the other one blonde. Brown fur is dominant over blonde fur. Both dogs are homozygous. What is the genotype of the parents?

1. AA x aa
2. Aa x AA
3. Aa x aa
4. Aa x Aa

What genotype does the F1 have? (first generation offspring)

P = AA x aa

What is the fenotype of the F2? (second generation offspring)

F1 = Aa x Aa

Exercises 

Please start with questions 1 through 9. Which will be homework for next lesson! 

See you all next week! 😊