A gene is a short piece of DNA. Genes tells the body how to build a specific proteins . There are about 30,000 genes in each cell of the human body. Together, these genes make up the blueprint for the human body and how it works.
A person's genetic makeup is called a genotype.
Genes are made of DNA. Strands of DNA strands make up part of your chromosomes . Chromosomes have matching pairs of one copy of a specific gene. The gene occurs in the same position on each chromosome.
Genetic traits, such as eye color, are dominant or recessive:
Many personal characteristics, such as height, are determined by more than one gene. However, some diseases, such as sickle cell anemia , can be caused by a change in a single gene.