4.6.2.1 Variation

Question 1

Describe how the genome and its interaction with the environment influence the development of the phenotype of an organism.

Answer 1

• Apart from identical twins everyone in the world has a different genome
• The way we look isn’t just due to our genes (for example a pair of identical twins may have the same genes of being tall but if one of them didn’t eat or sleep as much as the other then they might not be as tall)
• Most of our characteristics are determined by the interactions of our genes and the environment

Question 2

What are differences in characteristics of individuals (variation) due to?

Answer 2

• The genes that they have inherited (genetic causes)
• The conditions in which they have developed (environmental causes)
• A combination of genes and the environment

Question 3

Why is there so much genetic variation?

Answer 3

• There are so many different genes is because of mutations
• A mutation is a change in the DNA code so that the protein that it codes for may be different keep
• Most mutations don’t actually have any effect on the proteins and so don’t change the organism’s phenotype at all
• However in those cases where mutations do change proteins the phenotype may change slightly
• This change will usually be something bad and unwanted but very occasionally the mutations are beneficial (for example they could make them more resistant to lung disease or give us the ability to run faster)