2 Marfans Syndrome Cleft chin Colorblindness P olydactyly Widows peak Freckles Mendelian Genetics What do you remember about Mendel and his genetics studies from your first biology course ID: 1045803
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1. Genetics: Part IMendel and the Gene
2. 2 Marfans Syndrome Cleft chin Colorblindness Polydactyly Widows peak Freckles
3. Mendelian GeneticsWhat do you remember about Mendel and his genetics studies from your first biology course?What are some of the terms of genetics that you remember?3
4. Can you define these?GenotypePhenotypeMonohybridDominantRecessiveP1HomozygousHeterozygousAlleleTest crossF1F24
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6. PhenotypePurplePurplePurpleWhite31112Ratio 3:1Ratio 1:2:1GenotypePP(homozygous)Pp(heterozygous)Pp(heterozygous)pp(homozygous)
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9. Figure 14.1
10. Pp
11. 3. The pattern of inheritance (monohybrid, dihybrid, sex-linked, and genes linked on the same homologous chromosome) can often be predicted from data that gives the parent genotype/ phenotype and/or the offspring phenotypes/genotypes.Curriculum Framework
12. Mendelian GeneticsLaw of Dominance - if the two alleles at a locus differ, then one (the dominant allele) determines the organism’s appearance, and the other (the recessive allele) has no noticeable effect on appearance12
13. Human Traits with simple dominance:Widows peakHandednessFree earlobesCleft ChinDimplesFrecklesPTC testingPolydactylyBent little fingerNearsightednessMid-digit hair13
14. Frequency of Dominant AllelesDominant alleles are not necessarily more common in populations than recessive allelesFor example, one baby out of 400 in the United States is born with extra fingers or toesDominant does not mean numerous
15. In humans, alleles for dark hair are genetically dominant, while alleles for light hair are recessive. Which of the following statements is/are most likely to be correct?Dark hair alleles are more common than light hair alleles in all areas of Europe.Dark hair alleles are more common than light hair alleles in southern Europe but not in northern Europe.Dark hair alleles are equally common in all parts of Europe.Dark hair is dominant to light hair in southern Europe but recessive to light hair in northern Europe.
16. b. Segregation and independent assortment of chromosomes result in genetic variation. 1. Segregation and independent assortment can be applied to genes that are on different chromosomes. 2. Genes that are adjacent and close to each other on the same chromosome tend to move as a unit; the probability that they will segregate as a unit is a function of the distance between them.Curriculum Framework
17. Mendelian GeneticsLaw of segregation: the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes17
18. Figure 14.7Dominant phenotype,unknown genotype:PP or Pp?Recessive phenotype,known genotype:ppPredictionsIf purple-floweredparent is PP If purple-floweredparent is Pp orSpermSpermEggsEggsorAll offspring purple1/2 offspring purple and 1/2 offspring whitePp Pp Pp Pp Pp Pp pp pp p p p p P P P p TECHNIQUERESULTS
19. Figure 14.8P GenerationF1 GenerationPredictionsGametesEXPERIMENTRESULTSYYRRyyrryrYRYyRrHypothesis ofdependent assortmentHypothesis ofindependent assortmentPredictedoffspring ofF2 generationSpermSpermorEggsEggsPhenotypic ratio 3:1Phenotypic ratio 9:3:3:1Phenotypic ratio approximately 9:3:3:1315108101321/21/21/21/21/41/41/41/41/41/41/41/49/163/163/161/16YRYRYRYRyryryryr1/43/4YrYryRyRYYRRYyRrYyRryyrrYYRRYYRrYyRRYyRrYYRrYYrrYyRrYyrrYyRRYyRryyRRyyRrYyRrYyrryyRryyrr
20. Independent Assortment20
21. Practice In order to solidify your ability to explain the Laws of Segregation and Independent Assortment, describe how these laws would apply as sperm cells are developed in a man with genotype RrSs.Draw an image to support your explanation.21
22. Sample image22
23. Imagine crossing a pea heterozygous at the loci for flower color (white versus purple) and seed color (yellow versus green) with a second pea homozygous for flower color (white) and seed color (yellow). What types of gametes will the first pea produce?a. two gamete types: white/white and purple/purpleb. two gamete types: white/yellow and purple/greenc. four gamete types: white/yellow, white/green, purple/yellow, purple/greend. four gamete types: white/purple, yellow/green,white/white, and purple/purple