Genetics

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Genetics

  1. 1. Genetics Vocabulary Genetics- The branch of biology that studies biological inheritance.
  2. 2. Genetics Vocabulary Gametes = reproductive cells SPERM EGGS
  3. 3. Genetics Vocabulary Self-Pollination- When pollen from a plant fertilizes an egg from the same plant (this is how pea plants normally reproduce.)
  4. 4. Genetics Vocabulary Cross-pollination- produces seeds that are the offspring of two different plants . Pollen from one plant is dusted onto the ovules of another. This allow scientists to manipulate which plants reproduce together.
  5. 5. Genetics Vocabulary True-breeding- if allowed to self-pollination purebred peas would produce offspring identical to themselves. Tall pea plants only reproduce with tall for many generations
  6. 6. Genetics Vocabulary Traits – characteristics
  7. 7. Genetics Vocabulary Hybrids – organisms produced by crossing parents with different characteristics Example- crossing a tall pea plant with a short pea plant.
  8. 8. Puggles Labradoodles Jackapoos Chiweenies
  9. 9. Genetics Vocabulary Genes – The factors that control traits. Today we know these genes are located on specific sections of DNA.
  10. 10. Genetics Vocabulary Alleles- Different forms of a gene <ul><li>2 different alleles for a gene in a pea plant </li></ul><ul><li>Tall or short </li></ul><ul><li>Yellow or green </li></ul>
  11. 11. Genetics Vocabulary Dominant – the alleles that are “stronger” than others In Pea Plants Tall is Dominant to short.
  12. 12. Genetics Vocabulary Recessive – the weaker form of a gene In Pea Plants Only shows up if two are present. Short + short = short.
  13. 13. Genetics Vocabulary Punnett Square – a diagram used to determine the PROBABILITY of offspring from a particular cross. T = Tall t = short
  14. 14. Genetics Vocabulary Phenotype – the physical characteristics of an organism TALL YELLOW BLUE EYES RED HAIR PINK PETALS
  15. 15. Genetics Vocabulary Genotype – what an organism genetic makeup looks like TT GG Tt gg YY
  16. 16. Genetics Vocabulary Homozygous – has two of the same alleles. TT GG tt gg YY
  17. 17. Genetics Vocabulary Heterozygous – 2 different genes Tt Gg Yy
  18. 18. Mendel’s Conclusions <ul><li>The factors that control heredity are individual units known as genes. In organisms that reproduce sexually, genes are inherited from each parent. </li></ul><ul><li>In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and the other may be recessive. </li></ul><ul><li>The two form of each gene are segregated during the formation of reproductive cells. </li></ul><ul><li>Te genes for different traits may assort independently of one another. </li></ul>
  19. 19. Gregor Mendel <ul><li>Gregor Mendel, a monk in the Czech Republic, is considered the &quot;Father of Genetics&quot;, based upon experiments he conducted using garden peas. He helped lay down the principles of modern genetics. </li></ul>
  20. 20. Mendel’s Experiments <ul><li>Mendel was given a garden of pure bred pea plants. </li></ul><ul><li>He studied various traits in pea plants </li></ul>
  21. 21. The First Generation Cross (f 1 ) Mendel Crossed a purebred tall with a purebred short plant and got all tall plants! Step one = Define the Parents Genotype and Phenotype X Tall Short Phenotype = Genotype = TT X tt
  22. 22. The First Generation Cross (f 1 ) Step two = Set up the punnett square T T t t Mendel Crossed a purebred tall with a purebred short plant and got all tall plants! Phenotype = 100 % Tall Genotype = 100 % Tt Short X Tall Phenotype Genotype TT X tt Tt tall Tt tall Tt tall Tt tall
  23. 23. The Second Generation Cross (f 2 ) Mendel Crossed a two heterozygous Tall pea plants Step one = Define the Parents Genotype and Phenotype X Tall Tall Phenotype = Genotype = Tt X Tt
  24. 24. The Second Generation Cross (f 2 ) Step two = Set up the punnett square T t T t Mendel Crossed a purebred tall with a purebred short plant and got all tall plants! Phenotype = 75 % Tall: 25% short Genotype = 25% TT; 50%Tt; 25% tt Tall X Tall Phenotype Genotype Tt X Tt TT tall Tt tall tt short Tt tall
  25. 25. Review Mendel’s Conclusions <ul><li>The factors that control heredity are individual units known as genes. In organisms that reproduce sexually, genes are inherited from each parent. </li></ul><ul><li>In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and the other may be recessive. </li></ul><ul><li>The two form of each gene are segregated during the formation of reproductive cells. </li></ul><ul><li>Te genes for different traits may assort independently of one another. </li></ul>
  26. 26. Sample Problem #1 A yellow pod plant is crossed with a heterozygous pod plant. What is the genotype and phenotype of the offspring?
  27. 27. Sample Problem #2 A white flower pea plant is crossed with a homozygous recessive flower plant. What are the genotype and phenotypes of the offspring?
  28. 28. Sample Problems A heterozygous tall plant is crossed with a homozygous tall plant. What is the genotype and phenotypes of the offspring.
  29. 29. Two Trait Cross Mendel determined that alleles assort independently from each other, even when multiple traits are studied. Phenotype= 9:3:3:1 Genotype = 1:2:1:2:4:2:1:2:1
  30. 31. Sample Problem #1 A color point cat is crossed with a heterozygous normal cat. What are the expected genotypes and phenotypes of their offspring?
  31. 32. The British Royal Family Human traits are difficult to study for several reasons. Unlike some organisms, which produce slowly and only a few offspring at one time. Thus human traits must be studied through population sampling and pedigree analysis. A pedigree is a diagram that shows the phenotype of different generations. Royal family tree
  32. 36. Pedigree for ColorBlindness – a sex linked trait

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