Genetics intro. 8th


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Genetics intro. 8th

  1. 1. GENETICS
  2. 3. What is Genetics? <ul><li>Genetics is the science that studies the process of heredity. </li></ul>
  3. 4. What is heredity? <ul><li>The passing on of traits from parent to offspring. </li></ul>
  4. 5. What is a trait? <ul><li>A unique characteristic. </li></ul><ul><li>For example: hair color, eye color, height, tongue rolling, widows peak, etc </li></ul>
  5. 6. How are traits passed on? <ul><li>Traits are passed on from parent to offspring through DNA. </li></ul>
  6. 7. BrainPop DNA
  7. 8. What is DNA <ul><li>DNA is the chemical building block of life. </li></ul><ul><li>Every human cell contains a nucleus with DNA. </li></ul><ul><li>DNA is made up of 4 base pairs: </li></ul><ul><ul><li>Adenine, Thymine, Cytosine, and Guanine </li></ul></ul>
  8. 9. Watson and Crick <ul><li>Are the two scientists who discovered the shape of DNA. </li></ul><ul><li>They called the shape a double helix. </li></ul><ul><li>Each chromosome is a long strand of DNA. </li></ul><ul><li>Every cell has 23 homologous pairs of chromosomes </li></ul>
  9. 10. How does DNA make a human? <ul><li>The genetic code is spelled out with just four chemical letters, or bases: adenine (A), thymine (T), cytosine (C), guanine (G). </li></ul><ul><li>These pair up, A with T and </li></ul><ul><li>C with G. </li></ul><ul><li>The human genome has between 2.8 and 3.5 billion base pairs! </li></ul>
  10. 11. DNA double helix <ul><li>The base pairs form the rungs of the ladder-like DNA double helix. Running up and down the ladder are the long sequences of bases which are the code for life. </li></ul><ul><li>Each cell in the human body contains 2 meters (6 feet) of DNA! </li></ul>
  11. 12. DNA video
  12. 13. Genes <ul><li>As little as 3% of the total genome is made of genes - the rest is meaningless “junk”. </li></ul><ul><li>Genes are special sequences of hundreds or thousands of base pairs that provide the templates for all the proteins which the body needs to produce. </li></ul>
  13. 14. Chromosomes <ul><li>The total number of genes is not known. The estimate ranges from 30,000 - 120,000! </li></ul><ul><li>All genes are wrapped up into bundles called chromosomes. </li></ul><ul><li>Every human has 23 pairs of chromosomes, one half of each pair from each parent! </li></ul>
  14. 15. Nucleus and the cell <ul><li>The 46 chromosomes are held in the nucleus found in most cells in the human body. Nearly every cell in the body contains the full DNA code for producing a human. </li></ul>
  15. 16. Heredity <ul><li>Heredity is the passing on of traits from parent to offspring. </li></ul>
  16. 17. BrainPop ON Heredity
  17. 18. Dominant Trait <ul><li>The stronger of two traits. </li></ul><ul><li>Represented with a capital letter. </li></ul><ul><li>R </li></ul>
  18. 19. Recessive Trait <ul><li>The weaker of two traits. </li></ul><ul><li>Represented with a lower case letter. </li></ul><ul><li>r </li></ul>
  19. 20. Genotype <ul><li>Every one has two genes for a trait. One gene from mom and one gene from dad. </li></ul><ul><li>If mom gives you a dominant gene and dad gives you a recessive gene your genotype would be: </li></ul><ul><li>Rr </li></ul>
  20. 21. What is a genotype? <ul><li>The genotype is the genetic make-up of a trait. </li></ul><ul><li>The letters that represent the genes are the genotype. </li></ul><ul><li>Rr </li></ul>
  21. 22. Phenotype <ul><li>The phenotype is the physical characteristic that you can see. </li></ul><ul><li>For example: brown hair, brown eyes, widows peak, etc.. </li></ul>
  22. 23. Homozygous genotype <ul><li>If both parents give you a dominant gene, your genotype would be homozygous dominant . </li></ul><ul><li>RR </li></ul><ul><li>Homozygous - means both genes are the same! </li></ul><ul><li>If both parents give you a recessive gene, your genotype would be homozygous recessive . </li></ul><ul><li>rr </li></ul>
  23. 24. Heterozygous genotype <ul><li>If one parent gives you a dominant gene, and the other parent gives you a recessive gene, you will have a heterozygous genotype </li></ul><ul><li>Rr </li></ul><ul><li>Heterozygous - means the two letters are different </li></ul>
  24. 25. Punnett squares <ul><li>Are tools used in genetics to predict the genotype and phenotype of offspring. </li></ul>
  25. 26. How to use a Punnett square