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Non- Mendelian genetics

Non- Mendelian genetics. Complexity of Genetics:. In most cases, genetics are not as simple as presented in school There many factors and genes that contribute to the traits we see. Incomplete Dominance:. A heterozygous phenotype that is somewhere between the two homozygous phenotypes

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Non- Mendelian genetics

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  1. Non-Mendelian genetics

  2. Complexity of Genetics: • In most cases, genetics are not as simple as presented in school • There many factors and genes that contribute to the traits we see

  3. Incomplete Dominance: • A heterozygous phenotype that is somewhere between the two homozygous phenotypes • R = Red, r = white • RR = red, rr = white, Rr = pink

  4. Codominance • When two different alleles for the same gene are both expressed and cannot mask the expression of the other • Red Cows and White Cows, can combine to make an offspring called Roan, where both the Red and White show through

  5. Multiple Alleles • When three or more alleles exist for a single gene or trait

  6. Polygenic Inheritance • When more than one gene contribute to a trait • High blood pressure, obesity, etc.

  7. Blood Type • Considered an example of both codominance and multiple alleles • Two dominant traits, iA and iB • One recessive trait, i • Leads to the following blood types: • iAiA or iAi = A • iBiB or iBi = B • iAiB = AB • ii = O • O is the universal donor

  8. Sex Linked Traits: • Two types of chromosomes • Autosomes – all homologous chromosomes (#1-#22) • Sex Chromosomes – The two unmatched chromosomes that determine the sex of the individual

  9. Sex Chromosomes • Male genotype is xy • Female genotype is xx • The chromosome is much larger and can carry more genetic information

  10. Sex Linked Traits: • Controlled by the genes on the x-chromosomes • Examples: • Hemophilia – “Bleeders Disease” • Muscular Dystrophy – gradual destruction of muscle cells • Color Blindness – unable to perceive different colors • Male Pattern Baldness

  11. Sex Linked Traits: • Females can carry both the dominant and recessive traits on the x-chromosomes at the same time (a carrier for the recessive trait) • Males can only carry either the dominant or the recessive (only one x chromosomes) • Whatever is on the x chromosome for a male will be expressed (can never be a carrier)

  12. Practice #1: • In Snapdragons, the color Red (R) and White (W) only show through when they are homozygous. When they are heterozygous (RW) they are pink. Predict the genotype and phenotype ratios for a cross between two pink flowers. Include a Punnett square • Genotype: RR:RW:WW, 1:2:1 • Phenotype: Red:Pink:White, 1:2:1

  13. Practice #2: • A person with Type AB blood and a person with Type O blood have a child. What are the possible outcomes for blood type? What is the possibility that the child has Type AB blood? Type A or Type B blood type No chance for AB blood

  14. Practice #3: • Identify as many genotypes as possible for color blindness. Squares are men, blue means the presence of the gene:

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