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Genetics

Genetics. Mendelian Genetics. The passing of traits to the next generation is inheritance or heredity Mendel- a monk who work with pea plants Studied various traits in the peas. P, F1, and F2 Generations. Parent generation - P generation

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Genetics

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  1. Genetics

  2. Mendelian Genetics • The passing of traits to the next generation is inheritance or heredity • Mendel- a monk who work with pea plants • Studied various traits in the peas

  3. P, F1, and F2 Generations • Parent generation - P generation • P x P - F1 generation or first filial generation • F1 x F1 - F2 generation or second filial generation

  4. Genes in Pairs • Allele- alternative form of a single gene • Dominant- able to mask • Recessive- is masked

  5. Dominance • Homozygous- two of the same alleles • Homozygous dominant (both dominant alleles) • Homozygous recessive (both recessive alleles) • Heterozygous- two different alleles • Genotype- an organisms pair of alleles • Phenotype- observable characteristic

  6. Mendel’s Law of Segregation • Two alleles separate during meiosis • You have a 50-50 chance of giving each allele

  7. Monohybrid Cross • Cross a homozygous dominant plant and with a homozygous recessive plant • tall - dominant • dwarf - recessive • What do we expect the F1 and F2 Generations to look like?

  8. F1 Generation

  9. F2 Generation

  10. Dihybrid Cross Dihybrid Cross Law of Independent Assortment • Simultaneous inheritance of 2 traits in the same organism • Must be on different chromosomes • Different chromosomes separate independently • Genes on different chromosomes separate independently

  11. Cross two pea plants that are each hybrid for height (Tt) and also hybrid for pod color • (T-Tall and t- dwarf) • (Y=yellow and y=green)

  12. What would happen? • What would happen if two genes were on the same chromosome? (Circle one) • A. They sort independently of each other • B. They don’t sort independently of each other • Why

  13. Complex Inheritance and Human Heredity Albinism • Can affect only the eyes, skin, or hair or be complete

  14. Complex Inheritance and Human HereditySickle Cell Anemia • Autosomal Recessive • Red blood cells- sickle shape • heterozygotes have both normal and sickle-shaped cells • Heterozygotes protected from malaria • HH- no SCA/ get malaria • Hh- no SCA/ don’t get malaria • hh- afflicted with SCA 7766x Sickle cell

  15. Pedigrees • A diagram that traces inheritance • Can be used to predict genetic disorders in families

  16. Incomplete Dominance • The heterozygote phenotype is a blend between the two homozygous phenotypes

  17. Codominance • Both alleles are expressed at the same time

  18. Complex Inheritance and Human Heredity Epistasis • One allele can hide the effects of another allele eebb eeB_ E_bb E_B_ Dark pigment present in fur No dark pigment present in fur

  19. Sex Determination (mammals) • Sex Chromosomes • XX- female • XY- Male • Sex chromosomes determine gender

  20. Sex Linked Traits • Located on the X chromosome • Affects mostly males • Red Green Colorblindness • Hemophilia

  21. Polygenic Traits • Trait determined by many genes at many loci • Loci – locations on different chromosomes

  22. Explain The Twins

  23. Environmental Influences • Diet • Exercise • Sunlight and water • Temperature

  24. Look at you: nice work, human!

  25. Identical Twin Studies • Helps separate genetic contributions from environmental contributions • Traits that affect both twins are controlled partially by heredity • Traits expressed differently in identical twins are strongly influenced by the environment

  26. Karyotype Studies • Picture of the chromosomes arranged in decreasing size • Chromosomes are stained • Look for abnormalities • Number of chromosomes • Missing parts to chromosomes

  27. Male or Female?

  28. See anything different?

  29. Nondisjunction • During meiosis- sister chromatids fail to separate properly • Down syndrome • Sex Chromosomes

  30. Down Syndrome Trisomy 21 46+ #21 = 47 Turners Syndrome 46 – X=45 XO

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