multile choice q.docx

- Dominant and Recessive Traits - Traits are determined by pairs of genes. Each member of a pair of genes is termed an [**allele**](javascript://) - **Homozygous** having two identical alleles **heterozygous** having two different alleles - When the effects of both alleles are sho...

- Dominant and Recessive Traits - Traits are determined by pairs of genes. Each member of a pair of genes is termed an [**allele**](javascript://) - **Homozygous** having two identical alleles **heterozygous** having two different alleles - When the effects of both alleles are shown, the trait is said to have incomplete dominance, or codominance - People who bear one dominant gene and one recessive gene for a trait are said to be [**carriers**](javascript://) of the recessive gene - cystic fibrosis and sickle-cell anemia are from recessive genes - Chromosomal disorders reflect abnormalities in the 22 pairs of autosomes, down syndrome, or in the sex chromosomes, XXY, other are caused single pairs of genes, cystic fibrosis, epilepsy results from multifactorial problems, hereditary or genetic disposition with the environment - Chromosomal Abnormalities - Chromosomal abnormalities fall into 2 groups, numerical and structural, when a person is missing one, its called a monosomy, when a person more than two, not a pair, its called trisomy, ex. Down syndrome, - Advancing maternal age increases the risk of having a child with down syndrome, women between 35 to 39 have the highest percent change at 29% - Down syndrome is usually caused an extra chromosome in the 21^st^ pair, resulting in 47 chromosomes , 3 types of down syndrome, trisomy 21, translocation and mosaicism - Ther mongoloid or mental retardation were first offensive terms used - **sex-linked chromosomal abnormalities ;**abnormalities that are transmitted from generation to generation and are carried on the sex chromosome, numerous disorders stem from an abnormal number of sex chromosomes, infertile, maleness and femaleness differences - Genetic Abnormalities - Numerous disorders have been attributed to genes such as phenylketonuria, Huntington's, sickle cell anemia, tay-sachs and cystic fibrosis - Phenylketonuria: Transmitted by recessive gene, 1 in 12,000 newborns will have PKU,children with pky cannot metabolize an amino called phenylalanine, builds ups and impairs central nervous system, intellectual changes, physical disorders - Hunting disease: Fatal progressive brain disorder, brain cells die and person becomes less able to control movements, emotions, disease, genetic miracle discovered - Sickle cell anemia, recessive gene, common among black north Americans, neglected disease due to no precise stats, red blood cells take shape of sickle and clump together, decrease oxygen supply - Cystic fibrosis: recessive gene, most fatal among children and young adults, thick build up of mucus in the lungs, trouble absorbing nutrients - Sex linked genetic abnormalities, hemophilia, colour blindness, only carried on the x sex chromosomes, females less likely because they have two x chromosomes