This document discusses DNA structure and organization within cells. It describes how DNA is organized into genes that encode proteins, and how multiple genes together make up an organism's genome. DNA is packaged into chromosomes, which can further condense during cell division. The document outlines how DNA is wrapped around histone proteins to form nucleosomes, which allow for tight packing of DNA into chromatin and chromosomes. Post-translational modifications of histone proteins can affect chromatin structure and regulate gene expression.

1. Cell & Molecular
Biology

2. Genes

3. Chapter 5

6. DNA Structure

7. The Double Helix
and Base Pairing

10. Figure 5-6a Essential Cell Biology (© Garland Science 2010)

11. Figure 5-6b Essential Cell Biology (© Garland Science 2010)

12. Figure 5-7 Essential Cell Biology (© Garland Science 2010)

13. Information
in a linear sequence

14. Figure 5-8 Essential Cell Biology (© Garland Science 2010)

15. Figure 5-9 Essential Cell Biology (© Garland Science 2010)

16. Genes

17. “A gene is usually defined as
a segment of DNA
that contains instructions
for making a particular protein.”

18. Genome

19. “The complete set of information
in an organism’s DNA...”

20. Figure 5-10 Essential Cell Biology (© Garland Science 2010)

21. Chromosomes

22. Figure 5-11 Essential Cell Biology (© Garland Science 2010)

23. Human somatic cells
have 23 pairs of
homologous chromosomes

24. Figure 5-10 Essential Cell Biology (© Garland Science 2010)

25. We often look at
mitotic chromosomes

26. Figure 5-17 Essential Cell Biology (© Garland Science 2010)

27. But interphase chromosomes
are “less compact”

28. Figure 5-15 Essential Cell Biology (© Garland Science 2010)

29. Figure 5-18 Essential Cell Biology (© Garland Science 2010)

30. Chromatin

31. Figure 5-19 Essential Cell Biology (© Garland Science 2010)

32. “The complex of
DNA and proteins...”

33. Figure 5-21 Essential Cell Biology (© Garland Science 2010)

34. Chromosomal Structure

35. Linear information,
highly structured

36. Figure 5-21 Essential Cell Biology (© Garland Science 2010)

37. Nucleosomes

40. Histones

41. Figure 5-23 Essential Cell Biology (© Garland Science 2010)

42. Chromosome Packing

43. Figure 5-25 Essential Cell Biology (© Garland Science 2010)

44. http://www.mun.ca/biology/scarr/Histone_Protein_Structure.html

45. http://www.mun.ca/biology/scarr/Histone_Protein_Structure.html

46. http://www.mun.ca/biology/scarr/Histone_Protein_Structure.html

47. Changing Nucleosome Structure

48. Chromatin-Remodeling Complexes

49. Figure 5-27a Essential Cell Biology (© Garland Science 2010)

50. Figure 5-27b Essential Cell Biology (© Garland Science 2010)

51. Chemical Modification of Histones

52. Acetyl, methyl and phosphate groups
can be added to or removed from
histone tails.

53. Figure 5-28a Essential Cell Biology (© Garland Science 2010)

54. Figure 5-28b Essential Cell Biology (© Garland Science 2010)

55. These modifications can affect
30-nm chromatin fiber stability
and the ability of histone tails
to bind specific proteins.

56. Heterochromatin

57. “The most highly condensed form
of interphase chromatin...”

58. Figure 5-29 Essential Cell Biology (© Garland Science 2010)

59. Figure 5-30 Essential Cell Biology (© Garland Science 2010)

60. Euchromatin

61. “...chromatin that exists
in a more extended state...”

62. Figure 5-31 Essential Cell Biology (© Garland Science 2010)

63. Figure 5-31 Essential Cell Biology (© Garland Science 2010)