8 Law of Segregation Alleles separate during gamete production Gametes have one allele for each trait During fertilization gametes combine at random to form individuals of the next generation
9 Discovery of Chromosomes in 1900 Confirmed Law of Segregation Chromosomes are in pairs Each chromosome has one of the allele pair
10 Chromosomes line up in a double row. Meiosis Metaphase Assume a T allele on each red chromatid and a t allele on each blue chromatid TTtt
11 Chromosomes separate Each each daughter cell gets doubled chromosomes TT tt
12 Doubled Chromosomes Separate in Second Meiotic Division TT tt
13 Each gamete will have a T allele or a t allele TTtt
14 Allele Member of a paired gene –One allele comes from each parent Represented by a single letter
15 Dominant & Recessive Alleles Dominant alleles are expressed Recessive alleles are not expressed in the presence of a dominant allele –Recessive alleles are only expressed if both recessive alleles are present
16 Gene A unit of heredity that controls the development of one trait Made of DNA Most genes are composed of two alleles
19 Genotype Genetic make up Represented by alleles TT & Tt are genotypes for tall pea plants
20 Phenotype A trait Genotype determines the phenotype Tall is a phenotype
21 Homologous Chromosomes Chromosomes of the same pair Each homologue will have one allele for a paired gene Homologous chromosomes pair up during meiosis Only one of each homologue will be in each gamete
22 Sickle Cell Anemia RBCs sickle shaped Anemia Pain Stroke Leg ulcers Jaundice Gall stones Spleen, kidney & lungs
23 Sickle Cell Anemia Recessive allele s, codes for hemoglobin S –Long rod-like molecules –Stretches RBC into sickle shape Homozygous recessive ss, have sickle cell anemia Heterozygous Ss, are carriers
31 AA Aa aa Genotypes 1 AA, 2Aa, 1aa Phenotypes 3 Normal 1 Abino Probability 25% for albinism
32 A man & woman are both carriers (heterozygous) for PKU disease. What is the chance their children will inherit PKU disease?
33 p p P PP PpPp PpPp pp P PP = Normal Pp = Normal (carrier) pp = PKU disease
34 PP Pp pp Genotypes 1 PP, 2Pp, 1pp Phenotypes 3 Normal 1 PKU disease Probability 25% for PKU disease
35 A man with sickle cell anemia marries a woman who is a carrier. What is the chance their children will inherit sickle cell anemia?
36 s s s Ss ss S SS = Normal Ss = Normal (carrier) ss = Sickle Cell
37 Ss ss Genotypes 2 Ss, 2ss Phenotypes 2 Normal (carriers) 2 Sickle cell Probability 50% for Sickle cell
38 Dwarfism = D Normal height = d DD = Dwarfism Dd = Dwarfism dd = Normal height Dwarfism Dwarf Band
39 A man with heterozygous dwarfism marries a woman who has normal height. What is the chance their children will inherit dwarfism? Dwarfism is dominant.
40 d d D Dd dd Dd dd d DD = Dwarf Dd = Dwarf dd = Normal
41 Dd dd Dd dd Genotypes 2 Dd, 2dd Phenotypes 2 Normal 2 Dwarfs Probability 50% for Dwarfism
42 Law of Independent Assortment The inheritance of one gene does not influence the inheritance of another gene if they are on separate chromosomes. The gene for albinism does not affect the gene for dwarfism
43 Dihybrid Cross or Two Traits A heterozygous tall plant that is also heterozygous for yellow seeds is crossed with another plant with the same genotype Tall and yellow seeds are dominant to short and green seeds.
44 Tall Yellow TtYy TY What gametes can each parent produce? Ty tY ty TtYy TY Ty tY ty Tall Yellow
45 9 Tall-Yellow Match gametes on a Punnent Square TY Ty tY ty TYTytYty TtYy TTYYTTYyTtYY TTYyTTyyTtyy TtYYTtYyttYYttYy TtYyTtyyttYyttyy 3 Tall-Green 3 Short-Yellow 1 Short-Green
46 A man with blue eyes and normal height marries a woman with heterozygous brown eyes and heterozygous dwarfism. What are the possible phenotypes of their children? Dwarfism & brown eyes are dominant.
47 Normal height-Blue ddbb db What gametes can each parent produce? DdBb DB Db dB db Dwarf-Brown
48 DB Db dB db Match gametes on Punnent Square db DdBb Ddbb ddBb ddbb Dwarf-Brown eyes Dwarf-blue eyes Normal height-Brown eyes Normal height-Blue eyes