What is DNA?

You will remember from your Key Stage 3 studies that the cell's nucleus controls the activities of the cell. Look there if you need to remind yourself of animal and plant cells.

Chromosomes

Chromosomes are X-shaped objects found in the nucleusnucleus: The central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. of most cells. They consist of long strands of a substance called deoxyribonucleic acid, or DNA for short. A section of DNA that has the genetic code for making a particular protein is called a gene.

The gene is the unit of inheritance, and each chromosome may have several thousand genes. We inherit particular chromosomes through the egg of our mother and sperm of our father. The genes on those chromosomes carry the code that determines our physical characteristics, which are a combination of those of our two parents.

Nucleus, chromosome and gene

The bases in the DNA molecule carry the different codes needed for different amino acids. The code for a particular amino acid is made from three bases in a particular order. The animation shows the structure of DNA in more detail, but note that you do not need to know this for your examination.