Transcript Slide 1
Prepared by Katherine E. L. Norris, Ed.D. West Chester University This multimedia product and the content are protected under copyright law. The following are prohibited by law: any public performance or display, including transmission of any image over a network, preparation of any derivative work, including the extraction, in whole or in part of any images; any rental, lease, or lending of the program. Copyright © 2010, Pearson Education Inc., All rights reserved. Chapter 2 Heredity and Environment Copyright © 2010, Pearson Education Inc., All rights reserved. Genes and Human Reproduction How Traits and Genetic Abnormalities Are Inherited How Genes and Environments Interact Behavior Genetics: Measuring the Heritability of Traits Copyright © 2010, Pearson Education Inc., All rights reserved. In general, do you believe that traits like intelligence and personality are more inherited or more learned? Why do you believe this? Copyright © 2010, Pearson Education Inc., All rights reserved. Each one of us began as a single cell – a fertilized egg cell. Genes and the Magical Four-Letter Code Human Reproduction and Cell Division Copyright © 2010, Pearson Education Inc., All rights reserved. Chromosomes ◦ Strands of deoxyribonucleic acid molecules that contain the genetic code. DNA ◦ Two strands of molecules that twist around each other connected by a series of nucleotide bases. Gene ◦ A segment of DNA that provides an instruction for a particular structure, function, or trait. Human Genome Project ◦ An effort to map the nucleotide bases and genes contained in chromosomes. Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved. Fertilization ◦ The union of the father’s sperm cell with the mother’s egg Allele ◦ An alternative version of a gene; alleles operate in pairs across matched chromosomes Zygote ◦ Human organism after egg cell begins to divide Mitosis ◦ Copy division Copyright © 2010, Pearson Education Inc., All rights reserved. Meiosis ◦ Reduction division Monozygotic (MZ) Twins ◦ Identical twins ◦ These twins form when one zygote divides Dizygotic (DZ) Twins ◦ Fraternal twins ◦ These twins form when two eggs are fertilized by two different sperm cells Sex Chromosomes ◦ The 23rd pair of chromosomes specialized to determine the sex of the child Copyright © 2010, Pearson Education Inc., All rights reserved. Dominant-Recessive Traits Chromosome Abnormalities Prenatal Screening and Genetic Testing Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved. Dominant-Recessive Relationships ◦ To express a recessive trait, the individual needs to inherit two recessive alleles – one on each chromosome. Dominant Gene Diseases ◦ Individuals only need one dominant allele to inherit the trait. Recessive Gene Diseases ◦ Individuals must inherit two recessive alleles – one from each parent – to show the trait. X-linked (sex-linked) Traits ◦ Traits that differ in rate of occurrence between male and female. Copyright © 2010, Pearson Education Inc., All rights reserved. Down Syndrome ◦ A genetic disorder that occurs when there is an extra 21st chromosome. ◦ Low IQ, facial defects, heart problems, and shortened life span. Sex Chromosome Abnormalities ◦ Abnormalities in the number of sex chromosomes are among the most common of all human genetic disorders. ◦ Abnormalities occur in about 1 in every 500 live births. Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved. Ultrasonography (ultrasound) ◦ Images of the fetus inside the mother’s womb – produced by sound waves ◦ Used to help monitor fetal growth and detect defects Amniocentesis ◦ Procedure used to detect chromosomal and genetic abnormalities in the fetus ◦ A needle is inserted in the mother’s abdomen and cells are withdrawn from the amniotic fluid Chorionic Villus Sampling (CVS) ◦ A catheter is inserted into uterus and cells are taken to test. Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved. G x E Interaction ◦ The interacting effects of genetics and the environment on the development of traits and characteristics Copyright © 2010, Pearson Education Inc., All rights reserved. Range of Reaction ◦ Genotype The genetic code a person inherits ◦ Phenotype The observable trait a person shows, resulting in part from his or her inherited genotype ◦ Range of reaction The range of possible phenotypes that exist for a particular genotype Copyright © 2010, Pearson Education Inc., All rights reserved. Canalization ◦ Genetic limits on the effects of the environment Niche-Picking ◦ The tendency to pick activities and environments that fit with our genetic predispositions Probabilistic Epigenesis ◦ The likelihood that specific environmental conditions will activate specific genes that lead to specific outcomes Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved. How different are you from your siblings and parents? What accounts for the differences and similarities? Behavior genetics is a field that tries to answer these questions. Copyright © 2010, Pearson Education Inc., All rights reserved. Heritability ◦ Estimate of the degree of genetic influence for a given trait or behavior Shared Environments ◦ Experiences and aspects of the environment that are common across all individuals who are living together Nonshared Environment ◦ Experiences and aspects of the environment that differ across people Copyright © 2010, Pearson Education Inc., All rights reserved. Twin Studies ◦ Comparisons between measurements of identical and fraternal twins, used to estimate the genetic contribution to traits and characteristics Adoption Studies ◦ Comparisons between measurements of children and their adoptive and biological parents used to estimate the genetic contribution to traits and characteristics Copyright © 2010, Pearson Education Inc., All rights reserved. Heritability of Cognitive Skills ◦ Probably the most extensively studied behavioral trait is intelligence. ◦ A variety of cognitive skills have a significant hereditary component. Heritability of Personality and Temperament ◦ Genetics is an important influence on personality and temperament. Copyright © 2010, Pearson Education Inc., All rights reserved. Copyright © 2010, Pearson Education Inc., All rights reserved.