Chromosomes and DNA

• Chromosomes carry genetic information in a molecule called DNA.
• A type of cell division called mitosis ensures that when a cell divides each new cell produced has the same genetic information.
• DNA exists in a cell's nucleus within structures called chromosomes.
• The structure made of DNA that codes for all the characteristics of an organism is called a chromosome.
• Each section of a chromosome that contains the code for the production of a particular protein is called a gene.
• 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 micrographs.
• Each human body cell contains 46 chromosomes which 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.
• In males, one of the chromosomes is a different in shape.
• Males are referred to as XY.