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THE GENETIC MATERIAL

Explore the fundamentals of DNA and RNA, including nucleotides, nitrogenous bases, base-pairing rules, and the structure of DNA's double helix. Learn about DNA's role as the genetic material, its composition, and the basics of DNA technology and identification methods.

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THE GENETIC MATERIAL

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  1. DNA & RNA THE GENETIC MATERIAL

  2. Vocabulary you should know… • DNA: (deoxyribonucleic acid) the material that contains the information that determines inherited characteristics • Nucleotide: in a nucleic-acid chain, a sub-unit that consists of a sugar, a phosphate, & a nitrogenous base

  3. More Vocab… • Nitrogenous base: an organic base that contains nitrogen, such as a purine or pyrimidine; a sub-unit of a nucleotide in DNA or RNA • Purine: a nitrogenous base that has a double-ring structure; one of two general categories of nitrogenous bases found in DNA & RNA; either adenine or guanine

  4. More Vocab… • Pyrimidine:a nitrogenous base that has a single-ring structure; one of the two general categories of nitrogenous bases found in DNA& RNA; thymine, cytosine or uracil • Base-Pairing Rules: the rules stating that cytosine pairs w/ guanine & adenine pairs w/ thymine in DNA & adenine pairs w/ uracil in RNA

  5. More Vocab… • Complementary Base Pair: the nucleotide bases in one strand of DNA or RNA that are paired w/ those of another strand; adenine pairs w/ thymine or uracil, and guanine pairs with cytosine • Base Sequence: the order of nitrogenous bases on a chain of DNA • Double Helix: shape of a DNA molecule formed when two twisted DNA strands are coiled into a springlike structure & held together by hydrogen bonds b/t the bases

  6. DNA – deoxyribonucleic acid • The genetic information for an organism • DNA contains the instructions that cells need to make every protein required for essential life functions • Found mostly in the nucleus of cells • Composed of 100’s of 1000’s of repeating units of nucleotides

  7. DNA • Photographed through x-ray crystallography by Rosalind Franklin in the 1950s (w/ help from Maurice Wilkins) • 1st model was created by James Watson & Francis Crick in the ‘50s, with the use of Franklins x-ray crystallography picture

  8. Rosalind Franklin

  9. Maurice Wilkins

  10. James Watson & Francis Crick

  11. Made of subunits called nucleotides: 1 phosphate group 1 deoxyribose – simple sugar **this is what DNA is named for 1 of 4 nitrogen bases Either purines or pyrimidines DNA

  12. NITROGEN BASES • Purines: double ringed structure • Adenine (A) • Guanine (G)

  13. Nitrogenous Bases • Pyrimidines: single ringed structure • Thymine (T) • Cytosine (C)

  14. STRUCTURE OF DNA • Shape: double helix – repeating units of nucleotides **the sequence of nucleotides determines gene function

  15. DOUBLE HELIX • 2 chains of nucleotide monomers running anti - parallel • Phosphate groups make up the backbone of the double helix • Covalent bonds hold the nucleotides together by connecting the deoxyribose of one nucleotide to the phosphate group of the adjacent nucleotide

  16. Double Helix Cont’d • The nitrogen bases of the nucleotides pair up to link the 2 helixes • hydrogen bonds b/t the nitrogen bases hold the strands of the double helix together

  17. Double Helix Structure

  18. Base-Pairing Rules • Adenine (A) & Thymine (T) are always together • Cytosine (C) & Guanine (G) must then pair together

  19. DNA Basics Quiz • What is DNA? • The first person to photograph DNA was ____________. • The first people to make a model of DNA were ________ & ______. • A strand of DNA is made up of repeating units of __________.

  20. DNA Basics Quiz Cont’d • A nucleotide is composed of 3 parts, name all three. • List the 4 different nitrogenous bases. • Which part of the nucleotide makes up the backbone of the strand of DNA?

  21. DNA Basics Quiz Cont’d • What type of bonds hold the deoxyribose of one nucleotide to the phospate of the adjacent one? • What type of bonds hold the complementary nitrogenous bases together? • Out of Adenine, Guanine, Cytosine & Thymine, tell me the two complementary pairs.

  22. DNA Technology • DNA is manipulated for many different reasons: • Crime scene analysis • Genetic counseling • Research • Treatment of disease

  23. DNA Technology • DNA ID • Only identical twins have identical DNA • Only 10% of the human genome varies between all humans • The 10% that differs falls on the same chromosome region so we can isolate this DNA and use it to make important discoveries

  24. Identifying DNA • Step 1: Copying DNA: Polymerase Chain Reaction • Method of quickly copying DNA from small samples • Step 2: Cutting DNA: Restriction Enzymes • Restriction enzymes recognize specific short DNA sequences & cut in or near them • This isolates the DNA needed for ID

  25. Identifying DNA cont’d • Step 3: Sorting DNA by Size: Gel Electrophoresis • Gel electrophoresis separates DNA according to size and charge • Does this by running an electrical current through gel that the DNA cut by the restriction enzymes has been placed in, + & - charged pieces move to opposite ends • The resulting pattern is called the DNA fingerprint

  26. Identifying DNA • Step 4: Comparing DNA: DNA Fingerprints • Compare the DNA sample to other DNA fingerprints until you find a match, or pattern that you are looking for • Accuracy?? • The odds that 2 people will share the same DNA fingerprint: 1: 100 billion • # of people on Earth: approx 7 billion

  27. Gel Electrophoresis

  28. Recombinant DNA • Genetic engineering: the process of altering the genetic material of cells or organisms to allow them to make new substances • DNA recombination/Recombinant DNA: • Joining together DNA from two different organisms

  29. DNA Recombination • Step 1: isolate the DNA and the plasmid of interest • Plasmids: small rings of DNA found naturally in some bacterial cells in addition to the main bacterial chromosome • Step 2: restriction enzymes cut the DNA into fragments • Step 3: fragments and plasmid DNA are joined together permanently by DNA ligase

  30. DNA Recombination Cont’d • Step 4: recombinant DNA plasmids, each with different fragments of DNA, are inserted into bacterial cells • These recombinant DNA plasmids are then copied each time the bacterial cell copies its own DNA • Step 5: once a colony of bacterial cells containing the recombinant DNA plasmids is created, the recombinant DNA is removed to be used

  31. Recombinant DNA

  32. Central Dogma of Molecular Genetics • How we go from DNA to RNA • 1. replication (DNA copies itself) • 2. transcription (DNA acts as a template for the production of messenger RNA (mRNA)) • 3. translation(mRNA carries coded information to ribosomes; ribosomes "read" this information and use it to make proteins)

  33. The Central Dogma Cont’d

  34. Dogma Cont’d

  35. Replication: Vocab you should know… • DNA replication: process by which DNA is copied in a cell before a cell divides by mitosis, meiosis or binary fission • Helicase: enzymes that separate DNA strands by breaking the hydrogen bonds that hold the nitrogenous bases together

  36. Replication: More vocab… • Replication Fork: a Y shaped point that results when the two strands of DNA double helix separate so that the DNA molecule can be replicated • DNA Polymerase: an enzyme that catalyzes the formation of the DNA molecule

  37. Replication: More Vocab… • Semi-conservative Replicaiton: in each new DNA double helix, one strand is from the original molecule & one strand is new • Mutation: a change in the nucleotide-base sequence of a gene or DNA molecule

  38. Facts about Replication • Occurs during interphase of both the cell cycle for mitosis and for meiosis • Happens to all of the DNA in the cell, not just selected parts (every chromosome)

  39. Replication (of DNA) • Strands of DNA separate • Helicase enzymes move along the strand of DNA • They break the hydrogen bonds between the nitrogen bases • The two strands separate, exposing a a Y-shaped region called the replication fork

  40. Replication: Helicase & the Replication Fork

  41. Replication Cont’d • DNA polymerase enzymes add complementary nucleotides to the two separated strands • The nucleotides are found free-floating around inside the nucleus • As the nucleotides are added, covalent bonds form b/t the deoxyribose of one and the phosphate of the next

  42. Replication: Adding Nucleotides Cont’d • Adding nucleotides cont’d • Hydrogen bonds are formed b/t the nitrogenous bases from the original strand and the nitrogenous bases on the newly added nucleotides

  43. Replication: Adding Nucleotides Cont’d • Adding Nucleotides cont’d • DNA synthesis (creation) occurs in different directions on each strand • As the replication fork moves along the original DNA, synthesis of one strand, the leading strand, follows the movement of the replication fork • Synthesis of the other strand, the lagging strand, moves in the opposite direction, away from the replication fork

  44. Replication: Adding Nucleotide Cont’d • Adding Nucleotides Cont’d • Because the nucleotides are added to the leading and lagging strands in opposite directions, it leaves gaps in the newly synthesized DNA, called Okazaki Gaps • These gaps are later joined together by the enzyme DNA ligase

  45. Replication: Leading & Lagging Strands

  46. Replication Okazaki Fragments

  47. Replication Cont’d • DNA polymerase enzymes finish replicating the DNA & fall off The result of replication of a strand of DNA is two completely identical strands of DNA, each containing one old strand & one new stand = semiconservative replication

  48. Semi-Conservative Replication

  49. Replication cont’d • DNA replication flash interactive

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