Chromosomes in the cell nucleus
The genetic material in the nucleus of a cell is composed of a chemical called Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.. DNA is a polymer, a large and complex molecule. It is made up of two strands forming a twisted ladder structure called a The shape of the DNA molecule, with two strands twisted together in a spiral.. It carries the The code formed by the order of the bases in DNA that determines an organism's characteristics., which determines the characteristics of a living Living entity, eg animals, plants or microorganisms..
Except for identical twins, each person's DNA is unique. This is why people can be identified using DNA fingerprinting. DNA can be cut up and separated, which can form a 'barcode' that is different from one person to the next.
DNA exists in a cell's nucleus within structures called The structure made of DNA that codes for all the characteristics of an organism.. Each section of a chromosome that contains the code for the production of a particular protein is called a The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell's chemistry - particularly protein production..
Each chromosome is made from a single molecule of DNA, but when a cell is ready to divide, the DNA copies itself, then coils and condenses to form the chromosomes that we see in A photograph taken of a microscopical image..
Each human body cell contains 46 chromosomes. These can be arranged into 23 pairs.
Each chromosome in a pair carries the same types of genes. The 23rd pair are the sex chromosomes:
- In females, the two chromosomes are identical in shape. There are two X chromosomes. Females are referred to as XX.
- In males, one of the chromosomes is a different in shape. There is an X and also a Y chromosome. Males are referred to as XY.