Introduction to Human Genetics

Facts Humans have 46 chromosomes or 23 pairs of chromosomes 2 types of chromosomes: –Autosomes: chromosomes that determine body characteristics Chromosome pairs # –Sex chromosomes: chromosomes that determine gender/sex Chromosome pair #23

Cell Types We have 2 different types of cells: –Autosomal cells = Body cells Any cell that isn’t a sperm or egg Diploid (2n) = Full set of chromosomes (46) –Sex cells = gametes (sperm or egg) Haploid (1n) = ½ the set of chromosomes (23)

Human Genetics Humans are tough to study: –Long life span –Some traits determined through more than 1 set of genes (Ex. eye color, hair color) Most traits are autosomal dominant heredity –Inherited through dominant/rec. with 2 alleles –Ex. tongue rolling, earlobes –Huntingdon’s disease (dom. genetic disorder)

Genetic disorders A disease caused in whole or in part by a “variation” of a chromosome Passed through inheritance A small # of disorders are caused by a mistake in a single gene Most disorders involve more than getting the gene(s), also involve genetic changes or environmental influences (life style)

3 Categories of genetic disorders 1. Single Gene Disorders –Caused by mutations in one or both chromosomes (of a pair) –Usually recessive heredity –Ex. Sickle cell anemia, Cystic Fibrosis, Tay Sachs disease

2. Chromosome Disorders –Caused by an excess or deficiency of genes –Can be an extra chromosome (or part of one) or a missing chromosome (or part of one) –Ex. Downs syndrome, Turner’s syndrome, Kleinfelter’s syndrome

How we can diagnose chromosomal disorders

3. Multifactorial Inheritance Disorders –Caused by a combination of small variations in genes and/or environmental influences –Ex. Heart disease, Alzheimer’s disease, and some types of cancer