Fundamentals of Human Genetics

ABSTRACT

Deoxyribonucleic acid (DNA) is our genetic material. It is organized into structures called chromosomes. Most humans have 46 chromosomes, arranged in 23 pairs. DNA is divided into segments called genes. Data from the Human Genome Project suggest that humans have ~20,000 to 25,000 genes. A gene contains the instructions for making a protein, which is involved in some aspect of human growth and development. The processes by which proteins are made from DNA are transcription and translation. Mutations in genes cause changes in development, secondary to alterations in their protein products. Types of mutations include substitutions, deletions, and insertions. These mutations may cause conditions inherited in several patterns. In autosomal recessive inheritance, both alleles at a gene locus must have a mutation in order for a person to be deaf. In autosomal dominant inheritance, only one mutated allele is necessary to cause deafness. X-linked inheritance refers to the way mutations on the X chromosome are transmitted. Mitochondrial inheritance, multifactorial inheritance, digenic inheritance, and modifier genes are three forms of nontraditional inheritance.

KEYWORDS

DNA - gene - mutation - recessive - dominant

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