1. Mendel & the Gene Idea

2.  Bred garden peas in monastery  Character – heritable feature  Trait – variant for a character  Cross-pollinated true-breeding varieties of pea plant (hybridization)  “Parents” – P generation  Offspring – F 1 generation  F 1 offspring – F 2 generation Gregor Mendel – Pea-rific!

4.  P: purple & white  F 1 : all purple  F 2 : 75% purple 25% white  How?  Hypothesis… Mendel’s Work

5. 1.Alternative versions of genes (alleles) account for variations in inherited characteristics 2.For each character, you inherit one allele from each parent Mendel’s Work

6. 3. If the two alleles differ…  Dominant allele - fully expressed  Recessive allele – no noticeable effect on appearance Mendel’s Work

7. 4. Two alleles segregate (separate) during gamete production  Each gamete gets one  This is the Law of Segregation  Determined by Punnett square Mendel’s Work

9.  Homozygous – have two of same allele  Heterozygous – two different alleles  Phenotype – physical appearance & physiological makeup  Genotype – genetic makeup  Testcross – test unknown with homozygous recessive to determine unknown genotype Vocabulary to know

10. Test Cross

11.  Each different pair of alleles will segregate independent of any others during gamete formation  F 1 produced for single character – monohybrid  F 1 produced for two characters – dihybrid  Result of dihybrid cross - 9:3:3:1 Law of Independent Assortment

13.  Rule of Multiplication  Probability two independent events happen at same time – multiply each probability  Coin: H & H = ½ x ½ = ¼  F 1 is Pp – chance F 2 is pp?  Gamete has P = ½  Gamete has p = ½  ½ x ½ = ¼ Math Rules

14.  Dihybrid crosses  YyRr x YyRr  Probability of YYRR  Do a Punnett square for Yy x Yy  Get ¼  Do another for Rr x Rr  Get ¼  ¼ x ¼ = YY AND RR = 1/16 Math Rules

15.  Rule of Addition  Probability of event that can occur two or more different ways – add sum of separate probabilities  Example: cross two Heterozygous for flower color  probability that the offspring is heterozygous?  1)Mom’s recessive egg with dad’s dominant sperm – ¼  2)Dad’s recessive sperm with mom’s dominant egg – ¼  #1 OR #2  ¼ + ¼ = ½ Math Rules

16.  Incomplete Dominance  F 1 hybrids have intermediate characteristics  Ex: snapdragons  Not blending Mendel & Beyond

17.  Codominance  Two alleles in hybrid are BOTH expressed  Ex: blood types Mendel & Beyond

18.  Multiple Alleles  Blood type  A, B, AB, O  Three alleles – I a, I b, i  Presence or absence of carbo on surface  Wrong blood type – agglutination Mendel & Beyond

20.  Quantitative characters  Characters that vary along a continuum  Ex: human skin color  Indicates polygenic inheritance  Additive effect of two or more genes on single phenotypic character  Nature vs Nurture  Both often have an effect on gene expression Mendel & Beyond

22.  Chart with a pedigree Human Inheritance

23.  Recessively Inherited Disorders  Need homozygous recessive to have  Heterozygous are carriers & can pass on to offspring  Ex: Cystic fibrosis, Tay-Sachs, sickle-cell disease  Read details in text Human Inheritance

24.  Dominantly Inherited Disorders  Achondroplasia (dwarfism), cluster headaches  Affects homozygous dominant & heterozygous  If lethal, much less common – die before reproducing Human Inheritance

25.  If late-acting, can pass on dominant disorder  Ex: Huntington’s disease  Multifactorial Disorders  Genetics & environment play a role  Ex: diabetes, cancer, some mental illness Human Inheritance

26.  Fetal Testing  Amniocentesis  Chorionic villis sampling (CVS)  Ultrasound Technology