What does DNA strand mean?
DNA strand means Desoxyribonucleic acid;

Where can we find DNA?
DNA is the main structure of chromosomes and can be found inside the nucleus of all living cells.

What does DNA look like?
When DNA is observed with the naked eye, it looks like a ball of white thread.

When DNA is observed under a microscope, it can be seen in its chromosomal state, when cells divide or are about to divide. DNA observed with an electronic microscope looks like a fine thread covered with tiny balls. Specialists call this a string of beads. The beads are in fact “protective” proteins.

If we look closer, we can see that DNA is an assembly of two strands entwined in a double helix structure.

What is DNA for?

• DNA contains coded instructions for the development and functioning of all known living organisms, great and small.
  One piece of information = 1 gene = 1 protein
• • DNA is the medium of heredity. Contained in the sperm and ovum that form the embryo, DNA carries the traits of each parent and thus enables their transmission to children.

What is DNA made of?

Each strand of DNA is a polymer, i.e. a series of almost identical units (monomer), like a string of multicoloured beads. Each unit is called a nucleotide and is made up of one phosphate group, one sugar group (deoxyribose) and a nitrogenous base.

There are 4 different nitrogenous bases: adenine (A), thymine (T), cytosine (C) and guanine (G). All DNA molecules are made up of these 4 bases.

How does DNA structure explain the fact we are all different?

It is amazing to observe how different two human beings can be, even though they are both “made” from a chain of only 4 elements.

There are 256 possible combinations of 4 elements. However, each chromosome is made up of hundreds of millions of elements and we each have 23 pairs! Therefore, there are an infinite number of possible combinations. In fact, there is only a certain percentage of elements that can vary from one individual to another, but more than enough to ensure the diversity of the human race.