2 Gregor Mendel Genetics is the study of heredity. Gregor Mendel (1860’s) discovered the fundamental principles of genetics by breeding garden peas.
3 2. Mendel cross-pollinated pea plants He cut away the male parts of one flower, then dusted it with pollen from another
4 3. What did Mendel conclude? He concluded that factors are passed from one generation to the next.
5 4. The Principle of Dominance PaternalMaternaleye color locusb = blue eyeseye color locusB = brown eyes4. The Principle of DominanceThe Principle of Dominance – some alleles are dominant and other are recessive.Alleles1. Alternative forms of genes.2. Units that determine heritable traits.
6 5. Dominant and Recessive alleles Dominant alleles – upper-casea. homozygous dominant(BB – Brown eyes)Recessive alleles – lower casea. homozygous recessive(bb – blue eyes)b. Heterozygous (Bb – Brown eyes)
7 Phenotype vs. Genotype Outward appearance Physical characteristics Examples:1.Brown eyes 2.blue eyesArrangement of genes that produces the phenotypeExample:1. TT, Tt2. tt
15 Dihybrid Cross RY Ry rY ry RRYY RRYy RrYY RrYy RRyy Rryy rrYY rrYy Round/Yellow: 9Round/green:wrinkled/Yellow: 3wrinkled/green: 19:3:3:1 phenotypic ratioRRYYRRYyRrYYRrYyRRyyRryyrrYYrrYyrryy
16 Dihybrid CrossExample: cross between round and yellow heterozygous pea seeds.R = roundr = wrinkledY = yellowy = greenRrYy x RrYyRY Ry rY ry x RY Ry rY rypossible gametes produced
17 10. Independent Assortment This means all gametes will be different!Bbspermhaploid (n)meiosis IIChromosomes separate independently of eachotherBFBbmeiosis IBbFfbfBbdiploid (2n)BbFfBfBbFfBF
18 Independent Assortment Genes for different traits can segretate independently during the formation of gametes without influencing eachotherQuestion: How many gametes will be produced for the following allele arrangements?Remember: 2n (n = # of heterozygotes)1. RrYy2. AaBbCCDd3. MmNnOoPPQQRrssTtQq
19 Answer: 1. RrYy: 2n = 22 = 4 gametes RY Ry rY ry 2. AaBbCCDd: 2n = 23 = 8 gametesABCD ABCd AbCD AbCdaBCD aBCd abCD abCD3. MmNnOoPPQQRrssTtQq: 2n = 26 = 64 gametes
20 11. Incomplete DominanceOne allele is not completely dominant over anotherrRAll Rr = pink(heterozygous pink)produces theF1 generationRr
26 Is cloning a possibility? Is it right to use cloning to create an entirely new human being?Is it ethical to create an embryonic copy of John Doe to supply cells to keep John alive?Does a multicellular ball of tissue -- an embryo -- have the same rights and status as a human being?
27 How does Mendel’s principles apply to organisms The basic principals can be applied to humans as well as any other living organism.
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