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Genetics and Psychology. How much do genes decide our behavior? Pages 72-74. Genes: Our Code for life. Ms. Martin shares 98% with And 99.9% with . All cells contain DNA. Chromosomes and Genes. Each cell has 46 chromosomes = 23 pairs Genes give instructions to perform a certain function
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Genetics and Psychology How much do genes decide our behavior? Pages 72-74
Genes: Our Code for life • Ms. Martin shares • 98% with • And 99.9% with
Chromosomes and Genes • Each cell has 46 chromosomes = 23 pairs • Genes give instructions to perform a certain function • Two of this set are X and Y (the sex chromosomes) and the other 22 pairs guide the expression of other traits.
Dominant vs Recessive genes • 2 recessive genes = recessive trait • 1 dominant + 1 recessive = dominant • 2 dominant = dominant
Behavior Geneticists • Ask questions about the extent that genetics plays on our differences • Heritability – statistical estimate of how much behavior is due to genes. Max value is 1.0
Twin Studies • Identical Twins- develop from a single fertilized egg that splits in two, creating two genetically identical organisms • Fraternal Twins - develop from separate eggs • genetically no closer than brothers and sisters, but they share the fetal environment
Twins and heritability studies • Bouchard – studied 100 twins raised apart and their IQ scores • Those raised apart = coefficient of .69 on IQ test • Those raised together = .88 • Criticized = adopted parents have particular environment
Molecular Genetics • Looks at genes that can specifically cause disorders • Gender determined by 23rd chromosome pair • Men = XY – means some recessive characteristics from mother not blocked (color blindness) • Women = XX
Chromosomal Disorders • Turner’s Syndrome • Single X on 23rd pair • Shortness, webbed necks, sterility
Chromosomal Disorders • Klinefelter’s syndrome – XXY pattern • Males – less testosterone, weaker body, possible infertility • Down’s Syndrome • Extra chromosome on the 21st pair
Geneticists can now test for some disorders in Utero • Down’s syndrome • Tay-Sachs disease (death to nerve cells mental/physical deform. onset 6mo.-death @4) • Spina Bifida (one of most common in U.S. 1/1000 births – spinal) • Looking for an increase in a protein or hormone in early pregnancy