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Heredity

Heredity. Non-Mendelian Genetics. S-B-8-1_Non-Mendelian Heredity PowerPoint. Mendelian Heredity. Principle of Dominance  Law of Segregation Law of Independent Assortment. http://mac122.icu.ac.jp/gen-ed/mendel-gifs/01-mendel-himself.JPG. Non-Mendelian Heredity. does not fit Mendel’s Laws

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Heredity

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  1. Heredity Non-Mendelian Genetics S-B-8-1_Non-Mendelian Heredity PowerPoint

  2. S-B-8-1_Non-Mendelian Heredity PowerPoint Mendelian Heredity • Principle of Dominance  • Law of Segregation • Law of Independent Assortment http://mac122.icu.ac.jp/gen-ed/mendel-gifs/01-mendel-himself.JPG

  3. Non-Mendelian Heredity • does not fit Mendel’s Laws • is not governed by one autosomal gene S-B-8-1_Non-Mendelian Heredity PowerPoint

  4. Incomplete Dominance • Heterozygotes look different from a homozygotes • Blending of phenotypes RR x RIRI RRI http://chsweb.lr.k12.nj.us/psidelsky/Chapter10(Gen).htm S-B-8-1_Non-Mendelian Heredity PowerPoint

  5. Codominance: Both alleles of a gene pair are expressed. Example: Human Blood Types • Human blood type is determined by codominant alleles. There are three different alleles: IA, IB, and i. The IA and IB alleles are codominant, and the i allele is recessive. • The possible human phenotypes for blood group are type A, type B, type AB, and type O. • Type A and B individuals can be either homozygous (IAIA or IBIB, respectively), or heterozygous (IAi or IBi, respectively). Type O is IOIO. S-B-8-1_Non-Mendelian Heredity PowerPoint

  6. Codominance: More Examples Rhododendron coloration Roan coloration in cows (red coat with white blotches) http://en.wikipedia.org/wiki/File:Light_Roan_Shorthorn_Heifer_DSCN1872b.jpg http://upload.wikimedia.org/wikipedia/commons/f/f3/Co-dominance_Rhododendron.jpg S-B-8-1_Non-Mendelian Heredity PowerPoint

  7. S-B-8-1_Non-Mendelian Heredity PowerPoint THINK-PAIR-SHARE • Distinguish between incomplete dominance and codominance. • How many phenotypes are seen when codominance is possible? • Red color (R) in snapdragons shows incomplete dominance to white snapdragons (RI). The heterozygotes are pink. If pink snap dragons are crossed with a white snapdragon, what are the genotypic/ phenotypic ratios?

  8. S-B-8-1_Non-Mendelian Heredity PowerPoint Multiple Alleles • When 4 or more possible phenotypes exist within a population • Blood type • Eye & hair color • Fur in mammals http://www.learner.org/interactives/dna/genetics8.html

  9. S-B-8-1_Non-Mendelian Heredity PowerPoint Problems with Multiple Alleles A woman with type O blood marries a man with type AB blood. What are the possible blood types that a child of theirs could inherit? STEP 1: ♀ ii ♂ IAIB STEP 2: i IA , IB STEP 3: IA IB STEP 4: i IAi IBi STEP 5: STEP 6: There’s a 50% chance that their baby will be Type A or Type B.

  10. S-B-8-1_Non-Mendelian Heredity PowerPoint Polygenic Inheritance Poly-many genic-gene • More than one gene on more than one loci or on more than one chromosome. • Give the appearance of gradation • Hair & skin color • Height • Body size http://www.nature.com/nrg/journal/v10/n12/box/nrg2670_BX1.html http://scienceblogs.com/geneticfuture/a_ruler_beats_genetics_in_pred/tall_short1.jpg

  11. S-B-8-1_Non-Mendelian Heredity PowerPoint THINK-PAIR-SHARE Black fur (BBl) is completely dominant to brown fur in rabbits, but brown fur (BBr) is dominant to white (b). A hybrid brown doe (BBrb) is crossed with a hybrid black buck (BBlb). What are the expected phenotypes of the offspring? Ratios?

  12. S-B-8-1_Non-Mendelian Heredity PowerPoint Linked Traits • When the loci of two genes are located close together on the same chromosome • Red hair, freckles, and fair skin are linked. http://en.wikipedia.org/wiki/File:Woman_redhead_natural_portrait_1.jpg

  13. S-B-8-1_Non-Mendelian Heredity PowerPoint Sex-Linked Traits • Genes located on a sex (X or Y) chromosome ♀XX & ♂XY • Some forms of hemophilia • Red-green colorblindness http://www.ccs.k12.in.us/chsteachers/Amayhew/Biology%20Notes/sexlinked%20notes.htm

  14. S-B-8-1_Non-Mendelian Heredity PowerPoint Red-Green Colorblindness http://upload.wikimedia.org/wikipedia/commons/e/e0/Ishihara_9.png

  15. S-B-8-1_Non-Mendelian Heredity PowerPoint http://biology.clc.uc.edu/courses/bio105/sex-link.htm Hemophilia

  16. S-B-8-1_Non-Mendelian Heredity PowerPoint Barr Bodies • The inactive X chromosome found in female (XX) somatic cells • Not found in normal males (XY) . • Explains calico coloring in cats. http://www.genetics.com.au/factsheet/fs14.asp The nucleus of a cell. The arrow is pointing to the inactive X chromosome, the Barr Body.

  17. S-B-8-1_Non-Mendelian Heredity PowerPoint Calico Cats http://waynesword.palomar.edu/biex4hnt.htm

  18. S-B-8-1_Non-Mendelian Heredity PowerPoint Solving Sex-Linked Problems A woman who is a carrier for red-green colorblindness marries a man with normal sight. What percent of the male and female children will be red-green colorblind or carriers? STEP 6: STEP 1: ♀ XX'♂ XY 50% ♀ Normal 50% ♀Carriers 50% ♂Normal 50% ♂ Colorblind STEP 2: X, X' X, Y STEP 3: XY STEP 4: X X' XX XY STEP 5: XX' X'Y

  19. S-B-8-1_Non-Mendelian Heredity PowerPoint 1 2 7 3 8 4 5 6 THINK-PAIR-SHARE Wild Type Homozygous Heterozygous • Is the trait sex-linked? How do you know? • How could we tell if female #5 is heterozygous if she never has children? • What are the expected phenotypic ratios from a cross between #3 & #7? http://upload.wikimedia.org/wikipedia/commons/c/c5/Autosomal_Recessive_Pedigree_Chart_.svg

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