2. RNA processing and transport RNA degradation Translation
Gene Expression is regulated due to environmental and developmental cues:
DNA packaging
Transcription
RNA processing and transport
RNA degradation
Translation
Post-translational
Fig 16.1

3. For life to exist, the information (genes) must be passed on.

4. The Cell Cycle
Fig 7.23

5. DNA replication precedes cell division

7. DNA replication starts at the origin of replication

8. Eukaryotic initiation of replication
Fig 7.24

9. DNA replication starts at the origin of replication
Helicase unwinds/separates the two strands of DNA.

10. DNA replication starts at the origin of replication
The DNA is copied

11. The DNA is copied DNA replication starts at the origin of replication
More unwinding, more copying

12. DNA replication starts at the origin of replication
The DNA has now been copied. There are now two double-stranded DNAs

17. DNA polymerase can only use some DNA as template
Completely single stranded 3' 5'
Polymerase inactive
G
A A
T C
T
G
C
Completely double stranded 3' 5'
G
A A
T C
T
G
C
Polymerase inactive C
T T A G A C
G 5' 3'
Single strand as template plus 3' end to start synthesis
Figure: 12.8
Caption:
When DNA templates are completely single-stranded or double-stranded, no synthesis occurs. The DNA polymerases work only when there is a single-stranded template and a 3’ hydroxyl group available, as shown here. 3' 5'
G
A A
T C
T
G
C
Polymerase active
C T T 5' OH 3'

19. Fig 7.17

21. How do cell’s stitch together Okazaki
Fig 7.17

27. Proteins at work at the replication fork
Fig 7.19

28. Gyrase untangles DNA
Fig 7.19

29. Fig 7.16

30. Fig 7.22

31. Sometimes errors are made.

32. Error
Luckily, errors can be repaired.
As they occur by DNA polymerase

35. How does E. coli know which strand is new?

39. Errors are made during DNA replication
3,000,000,000 (3 billion) base pairs/human cell
with
1 error/1 billion base pairs not repaired
= (average)
~6 errors each time DNA is replicated

40. Not all errors get repaired.
These are mutations.

41. Telomeres are non-gene DNA at the ends of DNA strands.

42. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication.

43. The problem of replicating ends
Fig 7.25

44. Telomere lengthening by telomerase
Fig 7.26

45. Elongation of complementary telomere strand
Fig 7.26

46. The telomere forms a protective cap on the end of the DNA with several cap proteins
Fig 7.27

47. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication, and also by DNA damage.

48. Telomeres are non-gene DNA at the ends of DNA strands.
Short telomeres will cause cells to stop replicating or cell death.
The critical size is unknown.

49. Human
Life
Cycle
high levels of telomerase
very little telomerase

50. Why not produce telomerase all of the time?
high levels of telomerase
very little telomerase

51. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication, and by DNA damage.
Short telomeres will cause cell senescence or cell death.
Telomere size is a measure of mutations.

52. Do telomere dynamics link lifestyle and lifespan?
Pat Monaghan and Mark F. Haussmann
TRENDS in Ecology and Evolution Vol 21 pg 47

53. Telomere length varies in different parts of adults:
Telomere length varies in different parts of adults: telomeres - mitosis stomach & blood cells....short - often
muscle & brain……….long - rare
liver & kidney……..short - rare
gametes……long

54. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are more sensitive DNA damage, and may act as a sensor for overall DNA damage level in a cell.

55. Does telomere length indicate longevity?

56. Telomere length in red blood cells of different birds
Zebra finch
Age (years)
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47

57. Telomere length in red blood cells of different birds
common tern
Age (years)
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47

58. Telomere length in red blood cells of different birds
albatross
TRENDS in Ecology and Evolution Vol 21 pg 47

59. Telomere length in red blood cells of different birds
Leach’s storm petrel
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47

60. Telomere length in red blood cells of different birds, different species have different patterns of telomere length and age
Zebra finch
common tern
albatross
Leach’s storm petrel
Fig. 1 TRENDS in Ecology and Evolution Vol 21 pg 47

61. Telomere length in white blood cells of different aged people
Telomere length in white blood cells of different aged people. Telomere length generally declines, but there is wide variability
Fig. 2 TRENDS in Ecology and Evolution Vol 21 pg 47

62. Telomere length and mortality in people over 60 years old
upper 50% of telomere length
proportion surviving %
lower 50% of telomere length
years after initial assessment
THE LANCET • Vol 361 • pg 393

63. Telomere length may indicate biological age.
Early stress may cause premature telomere degradation.