1. Chapter 04

2. Information A living cell is self-organizing system A cell contains information and machinery for its own assembly, maintenance, repairs, and replication

3. Life Comes From Life Life flows from generation to generation in an unbroken chain Sudden spontaneous generation is impossible

4. Information in Living Things Life’s information is encoded in genes Genes are decoded by machinery that manufactures parts to make a living organism

5. Information Needs Difference to Be Useful

6. Genetic Discoveries 1860s – Mendel “Factors” determine inheritance Every trait is controlled by a pair of “factors” Traits have “dominant” and “recessive” forms

7. Dominant and recessive traits in the garden pea studied by Mendel

8. Genetic Discoveries 1890s Chromosomes discovered Suspected carriers of heredity Exist in pairs Double before cell division and are shared between daughter cells

9. Cell Division The chromosomes in this dividing cell have separated in a way that will provide a complete set of hereditary material to each new daughter cell. Alters fig. 4.16

10. Human Karyotype Karyotype: array of chromosomes that belong to an individual cell Human cells have 46 chromosomes

11. Genetic Discoveries 1903 – Sutton Trait-determining “factors” are located on chromosome pairs One chromosome comes from the mother’s egg, the other from the father’s sperm

12. Genetic Discoveries 1905 – Wilson & Stevens Specific chromosome carries specific hereditary property X chromosome determines sex of offspring Two X chromosomes in female cells, one X chromosome in male cells All eggs get X chromosome Half of sperm get X chromosome, other half get Y chromosome

13. Genetic Discoveries 1906 Mendel’s ‘factors” termed “genes” Chromosomes are chains of linked genes Many genes are inherited together

14. Genetic Discoveries 1908 - Morgan Farther apart genes are on a chromosome, the less likely they are to be inherited together Relative positions of genes along fruitfly chromosome are mapped

15. Genetic Discoveries 1909 - Garrod Certain inheritable diseases result when particular proteins fail to perform normal functions

16. Genetic Discoveries 1927 Mutations Changes in genes Produce new genetic characteristics and inherited diseases Necessary for evolution Can be produced with x-rays

17. Types of Mutations

18. Mutations and the Development of Cancer Cells

19. One Gene Makes One Protein

21. Genetic Discoveries 1944 - Luria Bacteria Subject to same genetic and evolutionary forces as plants and animals Reproduce rapidly Become main experimental subject of molecular genetics

22. Cloning a Human Gene in a Bacterium

23. Cloning a Human Gene in a Bacterium continued

24. Genetic Discoveries 1944 - Avery Genes are made of deoxyribonucleic acid (DNA)

25. DNA is Coiled Within Chromosomes

26. Nucleotide to Genome Nucleotide - smallest information unit Gene – string of nucleotides that specifies a protein Chromosome – spooled-up string of genes packaged in a single unit Genome – all of the chromosomes of a single organism

27. Nucleotide to Genome

28. Nucleotides 5-carbon sugar - deoxyribose (DNA) or ribose (RNA) Phosphate One of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), thymine (T) (RNA uracil (U) replaces thymine)

29. Nucleotides and DNA

30. Nucleotides – DNA and RNA

31. Nitrogen-containing Bases Purines: double-ring compounds Pyrimidines: single-ring compounds

32. DNA Deoxyribonucleic Acid Combinations of four nucleotides linked in long chains Repeating phosphate-sugar parts link together to form backbone

33. DNA Discoveries 1949 - Chargaff DNA from different organisms contain different amounts of the four nucleotides Amount of A = T Amount of G = C

34. DNA Discoveries 1952 – Wilkins & Franklin Examined shape of DNA using x-ray diffraction DNA exists in two or three chains with bases stacked near each other

35. DNA Discoveries 1953 – Watson & Crick Base pairing: A with T; G with C Sugar-phosphate forms double-helix backbone

36. DNA – Base Pairs Bases of nucleotides match up in pairs A pairs with T G pairs with C

37. DNA – Base Pairs DNA always exists as a double chain – one sequence of nucleotides paired with its complementary sequence

38. DNA – Base Pairs Weak bonds hold base pairs together Allows easy separation of chains for replication

39. DNA The Double Helix Resembles ladder twisted into a spiral Thin: easily packed into small places Double strand: protects inward-facing nucleotide sequence; essential for copying

40. The Structure of DNA

41. DNA Replication Before a cell divides, DNA must be doubled Each daughter cell receives a copy

42. The Stages of Mitosis Mitosis is the process of cell division that produces two identical cells from an original parent cell

43. DNA Replication Overview DNA separates Complementary nucleotides are linked along separated strands

44. DNA Replication Initiator protein guides unzipper protein (helicase) to correct position on DNA

45. DNA Replication Unzipper separates DNA strands, breaking weak bonds between the nucleotides

46. DNA Replication Builders (polymerases) assemble new DNA strand by joining nucleotides to their matching complements on the exposed strands

47. DNA Replication Phosphate bond energy from the new nucleotides is used to make the new bonds

48. DNA Replication Top strand is built continuously as the builder follows behind the unzipper, but the lower strand builds in the opposite direction

49. DNA Replication Lower builder makes a loop with the DNA strand and builds along the bottom half of it

50. DNA Replication Bottom new strand is assembled in short lengths which are spliced together by the stitcher (ligase)

51. DNA Replication Straighteners (single-strand DNA binding proteins) keep single strand of DNA from tangling

52. DNA Replication Untwister (topoisomerase) unwinds the DNA double helix in advance of the unzipper

53. Overview of DNA Replication

54. Multiplying DNA Using PCR

56. DNA Fingerprinting Using Gel Electrophoresis

57. Sequencing a Gene

58. Overview of DNA Replication

59. Repair Enzymes Erasers (Repair Nuclease): find poorly matched or damaged nucleotides and cut them out

60. Repair Enzymes Builders (Polymerase): fill gaps using other DNA strand as a guide

61. Repair Enzymes Stitchers (Ligase): uses ATP to restore continuity of backbone of repaired strand

62. Life is Orchestrated by Proteins Proteins Combinations of 20 different amino acids linked in long chains Function is determined by amino acid sequence Amino acid sequence is determined by DNA sequence

63. Amino Acids Link Together to Form a Protein (Polypeptide)

64. Transcription DNA is located in the nucleus DNA’s instructions must reach ribosomes in cell’s cytoplasm to make proteins Transcription: cell makes a disposable copy of pertinent genes (messenger RNA) and sends it to the protein assembly site (ribosomes)

65. Sending Information from the Nucleus

66. Nucleus Contains DNA Nuclear envelope: double outer membrane Nuclear pores: passageways for molecules entering and leaving nucleus Link to Cell Structure

67. Messenger RNA Made in nucleus Moves through nuclear pores to cytoplasm Brings information from DNA to ribosomes to direct synthesis of proteins

68. Transcription Making a Messenger The enzyme RNA polymerase binds to a gene on a DNA strand (at the promoter site) and opens up the double helix

69. Transcription Making a Messenger RNA polymerase moves along the exposed DNA strand, adding complementary RNA nucleotides which form the messenger

70. Transcription Making a Messenger As the messenger is assembled, it separates from the DNA template strand

71. Transcription Making a Messenger When the RNA polymerase arrives at stop sequence at end of gene, the messenger RNA strand is released

72. DNA Packaging DNA packaged to ensure message will get to next generation Examples: pollen, nuts, seeds, spores, sperm, egg Often carry food to sustain early stages of new life Contain machinery for DNA to get foothold