Unit2 lesson1-dna


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Unit2 lesson1-dna

  1. 1. UNIT 2 - DNA & DNA REPLICATION CH 7.1 & 7.2 P. 137-148
  2. 3. THE UNITS OF DNA <ul><li>DNA is a polymer. </li></ul><ul><li>The monomer units of DNA are nucleotides, and the polymer is known as a &quot;polynucleotide.&quot; </li></ul><ul><li>Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the sugar, and a phosphate group. </li></ul>
  3. 5. NUCLEOTIDES <ul><li>There are four different types of nucleotides found in DNA, differing only in the nitrogenous base. The four nucleotides are given one letter abbreviations as shorthand for the four bases. </li></ul><ul><ul><ul><ul><li>A is for adenine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>G is for guanine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>C is for cytosine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>T is for thymine </li></ul></ul></ul></ul>
  4. 6. Purine & Pyrimidine Bases <ul><li>Adenine and guanine are purines. </li></ul><ul><li>Purines are the larger of the two types of bases found in DNA. </li></ul><ul><li>Cytosine and thymine are pyrimidines. </li></ul>
  5. 7. DNA BACKBONE <ul><li>The DNA backbone is a polymer with an alternating sugar-phosphate sequence. </li></ul><ul><li>The deoxyribose sugars are joined to phosphate groups in ester links, also known as &quot;phosphodiester&quot; bonds. </li></ul><ul><ul><li>Important bonds that can’t break </li></ul></ul>
  6. 8. DNA DOUBLE HELIX <ul><li>DNA is a normally double stranded macromolecule. Two polynucleotide chains, held together by weak hydrogen bonds, form a DNA molecule. </li></ul><ul><ul><li>Note H-bonds are an attraction that can pull apart and go back together relatively easily </li></ul></ul><ul><li>P. 144 FIG 7-11 </li></ul><ul><li>Also note the two strands run in opposite directions </li></ul>
  7. 10. FEATURES OF THE DOUBLE HELIX <ul><li>The two polynucleotide chains run in opposite directions </li></ul><ul><li>The sugar-phosphate backbones of the two DNA strands wind around the helix axis like the railing of a spiral staircase </li></ul><ul><li>The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase. </li></ul>
  8. 11. SEE FIG 7-10 p. 143 in your TEXT BOOK
  9. 13. SO WHAT IS THE POINT? <ul><li>DNA is the brains of every cell because it contains all of the genes that are the codes for making proteins </li></ul>
  10. 14. PURPOSE OF DNA <ul><li>DNA has two major purposes </li></ul><ul><ul><li>DNA REPLICATION http://www.youtube.com/watch?v=rpwjZX_z5rg </li></ul></ul><ul><ul><li>PROTEIN SYSNTHESIS </li></ul></ul>
  11. 15. DNA REPLICATION <ul><li>Replication = when more cells need to be produced, COMPLETE copies of the original DNA must be made </li></ul><ul><ul><li>MITOSIS - nuclear division plus cytokinesis, to produces two identical daughter cells for growth and development of an organism </li></ul></ul><ul><ul><li>MEIOSIS - results in the production of gametes with only 1 set of DNA </li></ul></ul><ul><ul><li>(more details later!) </li></ul></ul>
  12. 16. PROTEIN SYNTHESIS <ul><li>Protein synthesis = when proteins are needed as enzymes that control all of the reactions in a cell, PARTIAL copies of a piece of DNA called a gene must be transcribed to be then translated into an amino acid polymer = protein = enzyme </li></ul>