Mechanisms of Genetic Influence: How do genes work? Biological Influences – Chromosomes and DNA Chromosomes-23 pairs total – Autosomes: 22 pairs – Sex Chromosomes: 1 pair, XX or XY DNA
How Genes Influence Traits Genes and their functions – Sections of DNA – Carries genetic information – Alleles Genotypes: The genetic makeup Phenotypes: How it’s represented – The Inheritance Sex Mother: XX Father: XY
Hereditary Diseases DisorderDescription Cystic Fibrosis Inadequate mucus production; breathing & digestive problems, early on- set Phenyketonuria (PKU) Metabolism of phenylalanines in food is insufficient; gradually compromises the nervous system; causes mental retardation Sickle-cell anemia Blood cells have an unusual “sickle” shape; causes heart and kidney problems Tay-Sachs Disease Enzyme disease; causes degeneration of the nervous system and death in the first few years of life. Thalassemia Blood cells abnormal; low energy; paleness, poor resistance to infection Hemophillia Blood-clotting factor not produced; vulnerable to death by bleeding Duchenne’s Muscular Dystrophy Wasting of muscles; produces gradual weakness; eventual death
Hereditary Diseases Disorders influenced by Dominant, defective alleles Disorders of polygenic origin Disorders caused by Chromosomal Abnormalities – Trisomy 21 Sex-Linked Disorders
Healthy Prenatal Development Three stages of development – Ovum, or gamate (first three weeks) Neural tube – Embryo (week 3 to 9) Cephalo-caudal – Fetus (week 9 to birth)
Environmental Influences on Prenatal Development Teratogens: – Mother's use of legal and illegal drugs pose serious risks to the unborn child: aspirin can lead to bleeding thalidomide caused missing limbs marijuana restricts oxygen to the fetus cocaine restricts blood flow and oxygen, babies are born addicted and go through withdrawal; they are shorter and weigh less; they have serious respiratory problems and birth defects or seizures; it is often impossible to soothe them.
Environmental Influences on Prenatal Development Both alcohol and cigarettes can disrupt the development of the fetus: -just two drinks a day has been associated with lower intelligence; ~FETAL ALCOHOL SYNDROME (FAS) is a disorder caused by the pregnant mother consuming substantial quantities of alcohol during pregnancy potentially resulting in mental retardation, delayed growth, and facial deformities;
Environmental Influences on Prenatal Development Illness in a pregnant woman can have devastating consequences: - Rubella (German measles) prior to the 11th week can cause blindness, deafness, heart defects, or brain damage. - Chicken pox and mumps may cause birth defects and miscarriage, respectively. - Syphilis and gonorrhea can be transmitted to the child. - Babies born with AIDS can have birth abnormalities including small, misshapen faces, protruding lips, and brain deterioration. 90 percent have neurological delays and deficits in motor coordination, speech, and facial expression. In addition, they are susceptible to infection. Survival past infancy is rare.
Environmental Influences on Prenatal Development Nutrition Stress – Eustress – Distress – Stages Alarm Resistance Exhaustion