there are approximately _____________ functional genes in human chromosomes.
A gene is a segment of DNA containing the code used to synthesize a protein. A chromosome contains hundreds to thousands of genes. Every human cell contains 23 pairs of chromosomes, for a total of 46 chromosomes. A trait is any gene-determined characteristic and is often determined by more than one gene. Some traits are caused by abnormal genes that are inherited or that are the result of a new mutation.