1 Why are family members alike but not identical?

• Look at a family photograph.
• Children resemble their parents in some features and differ in others.
• Genetics is the science that explains these similarities and differences by studying how genetic information passes from parents to offspring.

• The genetic information is stored in a chemical substance called the genetic material, deoxyribonucleic acid (DNA).
• In a cell, the genetic material is in the nucleus.
• A DNA molecule is extremely long, so it is coiled around protein molecules to form thread-like chromosomes.
• The genetic material of a chromosome is divided into sections; each section is a gene.

A gene is a segment of the genetic material (DNA) that carries the information responsible for a specific inherited trait, such as eye colour, hair texture or height.

So: cell → nucleus → chromosomes → genes (DNA).