Key Concept 2: Genetics and Inheritance

Question 1

What are genes?

Answer 1

Genes are located on chromosomes. We have 23 pairs of chromosomes (46 in total). Each is made up of strands of DNA , instructions for our development as living organisms.

Question 2

Genotype

Answer 2

Our actual genetic make-up. The collection of genes we inherit from our parents.

Question 3

Phenotype

Answer 3

How genes are expressed in observable characteristics e.g. brown hair, calm temperament etc. It is a result of interaction between our environmental influences and our genetics. For example, identical twins could have different body shapes due to exercise and diet, despite having exactly the same genetics.

Question 4

SRY gene

Answer 4

Our biological sex is determined by one pair of chromosomes. For girls this is XX and for boys this is XY. The SRY gene is what makes fetuses develop as male and this is located on the Y chromosome. At around 7 weeks into development before birth this switches on other genes causing the development of testis.