2. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Forming a New Life: Conception, Heredity, and Environment Chapter 2

3. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Guideposts for Study 1.How are birth defects and disorders transmitted?

4. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Mechanisms of Heredity Genetic and Chromosomal Abnormalities Some defects are due to abnormalities in genes or chromosomes, which may result from ________________ Many disorders arise when an inherited predisposition interacts with an environmental factor, either before or after birth

5. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Mechanisms of Heredity Genetic ____________________ A chart called a _______________ can show chromosomal abnormalities and can indicate whether a person who appears normal might transmit genetic defects to a child

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Should genetic counseling be compulsory before marriage?

7. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Defects Transmitted by Dominant Inheritance ____________ genes are usually dominant When one parent has a dominant abnormal gene and one recessive normal gene and the other parent has two recessive genes, each of their children has a 50:50 chance of inheriting Example – ___________________disease

8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Defects Transmitted by Recessive Inheritance _____________ defects are expressed only if a child receives the same recessive gene from each biological parent Defects transmitted by recessive inheritance are more likely to be __________ at an early age Example – _________________

9. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Cystic fibrosis Body makes too much _______________ Children do not grow normally Usually do not live beyond age ________ Most common inherited lethal defect among ________________ people

10. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Duchenne’s Muscular Dystrophy __________disease usually found in males Marked by muscle weakness, minor mental retardation Respiratory failure and death usually occur in ______________ adulthood

11. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Spina Bifida Incompletely closed spinal canal, resulting in muscle weakness or paralysis and loss of bladder and bowel control Often accompanied by ________________ which is an accumulation of spinal fluid in the brain (may lead to mental retardation)

12. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Sickle-cell anemia Deformed, fragile ________ blood cells that can clog the blood vessels – deprives the body of _____________ Symptoms include severe pain, stunted growth, frequent infections, leg ulcers, gallstones, susceptibility to pneumonia, and stroke Found among ______________ descent

13. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Tay-Sachs Disease Degenerative disease of the brain and nerve cells Results in death before age ______ Found among people of European ___________ descent

14. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Defects Transmitted by Sex-Linked Inheritance Sex-linked inheritance: Pattern of inheritance in which certain characteristics carried on the X chromosome inherited from the mother are transmitted differently to her male and female offspring.

15. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Chromosomal Abnormalities Down syndrome: Chromosomal disorder characterized by moderate to severe mental retardation and a downward sloping skin fold at the inner corners of the eyes. Also called _________________________

16. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Sex Chromosome Abnormalities Fragile X Minor-to-severe mental retardation Symptoms more severe in ______________ Include delayed speech and motor development, speech impairments, hyperactivity The ___________ common inherited form of mental retardation