1. The
Life
Cycle of
Cells

2. Cell Growth A cell is limited by its cell size
The larger the cell the harder it is to move through tissue and get nutrients
In order to stay alive and not grow continuously, the cell will divide

3. Reasons why to divide DNA Transport Genetic information stored
Found in the nucleus of the cell
DNA would not be able to keep up with demand of the cell
Transport
Rate decreases as the cell size increases
Takes too long for nutrients and wastes to move in and out of cell

4. Surface Area to Volume Surface Area
Area on outside of cell where reactions can occur
As a cell increases, the surface area decreases

5. DNA Structure Monomer of DNA is a nucleotide
5-carbon sugar
Phosphorous group
Nitrogenous base
4 Nitrogenous bases in DNA
Adenine
Guanine
Thymine
Cytosine

6. DNA Structure Backbone of DNA is the sugar and phosphate
Nitrogenous bases stick out of side to form latter rungs
These bases are repeated in a pattern that form our genetic code

7. DNA Structure Chargaff’s Rule
Scientist that discovered a peculiar trend between the 4 bases
Same percentage of Adenine as Thymine
Same percentage of Guanine as Cytosine
Scientists still not sure how they match up though

8. DNA Structure Rosalind Franklin
Scientist that worked with X-ray diffraction
Used X-rays on a portion of DNA and the results showed an X pattern

9. DNA Structure Watson & Crick
Scientists that were able to figure out what Rosalind’s X-ray pattern
Result: DNA has a double helix pattern where the nitrogenous bases face each other

10. DNA Structure DNA has a double helix pattern
Looks like a ladder twisted up
The sides of the ladder are the sugar and phosphate and the rungs of the ladder are the nitrogenous bases paired up
The adenine binds to thymine
The guanine binds to cytosine
This concluded Chargaffs’s rule  base pairing

11. DNA and Chromosomes Prokaryotes Eukaryotes Lack nucleus and organelles
DNA floats as a circle in the cytoplasm
Eukaryotes
1000 times more DNA than prokaryotes
DNA is located in nucleus
Specific number of chromosomes
Ex: Humans have 46 chromosomes

12. DNA and Chromosomes DNA Length Chromosome Structure DNA is very long
DNA is coiled up into a very small space because it is in chromatin form
Chromosome Structure
Tightly packed chromatin is wrapped around small proteins called histones
When chromatin gets super coiled you create a chromosome

13. Chromosomes Made up of our DNA Holds genetic information
Tight coils or rod like structures
Organisms have a specific amount of chromosomes.
Humans have 46 chromosomes of DNA in every somatic cell

14. Chromosome Structure
Histones are proteins that DNA wraps around to make the chromosome shape
Chromosomes are made of two sister chromatids
Identical to each other

15. Chromosomes Centromeres are in the center of a chromosome
Chromosomes are tightly coiled strings of DNA called chromatin
Chromatin is the string-like form of DNA

16. Chromosome Numbers A diploid cell contains 2 sets of each chromosome
Prefix di = 2
A haploid cell contains only 1 set of each chromosome
Half of the total number
Usually sex cells

17. Chromosome Numbers
There is a specific number of chromosomes in each organism
Humans autosomes and sex chromosomes
We have 2 sex chromosomes
Either X or Y
We also have 22 autosomes
Which do not code for gender

18. Karyotype
A karyotype is a lab picture of one set of chromosomes

19. How Replication Occurs
Enzymes help make new strands of DNA
One enzyme “unzips” the DNA, separating the base pairs
DNA polymerase adds new bases to pair up with the template
This enzyme also proofreads to make sure everything matches
What would be the matching bases to the part of DNA shown below?

20. DNA Replication
Each strand of DNA is needed to be a template for a new strand of DNA to be produced
Since you can use one strand to make the other side, they are said to be complementary

21. Duplicating DNA
Before mitosis occurs, DNA needs to be duplicated first during interphase
When DNA duplicates, its called replication
DNA molecules separates into two strands, then produces two new complementary strands following the rules of base pairing
Each strand serves as a template for the new strand

22. Cell Division in Prokaryotes
No nucleus
No organelles
Ex: Bacteria
Reproduction is VERY fast
Copy DNA
Split into two cells
Cell division is called binary fission

23. Eukaryotic Cell Reproduction
Eukaryotes
Have a nucleus
Have organelles
Ex: Humans, plants
Complex reproduction
Everything needs to be controlled!
Much longer process – about 18 hours!

24. Cell Reproduction A cell splits to make 2 identical copies
If asexual reproduction
Only 1 cell involved
This occurs in 3 main stages
Interphase – Growth
Mitosis – Splitting of the cell
Cytokinesis – Splitting of the cytoplasm

25. Interphase Cell growth 90% of cell’s life is spent in interphase.
3 Part of Interphase:
G1, S, G2

26. G1 Phase
The cell is growing
The organelles are doubling

27. S Phase Takes place when cells are too big S = Synthesis of DNA
DNA is replicated so there is a set for each new cell

28. DNA replicates in Interphase so the daughter cells exact copies of the DNA

29. G2 Phase Cell growth again Replication of organelles
Last stage of interphase
Cell prepares for cell division

30. Interphase cell is not dividing
cell is growing, performing respiration, producing, photosynthesizing, doing whatever functions it is supposed to do
At some point, the cell can’t diffuse fast enough and that signals the end of interphase
At the very end of interphase, the chromatin makes an exact copy of itself in a process called DNA replication.

31. How is DNA copied? Each cell has an protein called helicase
Enzyme the unwinds the DNA making 2 identical strands

32. Mitosis
The part of a cell’s life cycle when the cell divides it nuclear contents into 2 nuclei which are identical
Mitosis consists of 4 steps:
Prophase
Metaphase
Anaphase
Telophase

33. Prophase all sub-cellular organelles disappear
centrioles separate and move to opposite poles
chromatin become chromosomes
centrioles shoot off spindle fibers (short and long)

34. chromosomes line up at the equator
Metaphase

35. Anaphase centromere splits
sister chromatids attach to the short spindle fibers
short spindle fibers shorten and bring the sister chromatids to opposite poles.

36. Telophase chromatids become chromatin (one at each pole)
spindle disappears
subcellular organelles reappear

37. Cytokinesis Once mitosis has finished!
Last stage of cellular reproduction
This process is when the cytoplasm splits apart
There are now 2 identical cells

38. Cytokinesis in Plant Cells
Cell plate forms at equator and grows out to the cell wall
Cell plate

39. Cytokinesis in Animal Cells
Cell membrane pinches in at equator
Cleavage furrow

40. Interphase

41. Prophase

42. Metaphase

43. Anaphase

44. Telophase

45. Prophase

46. Metaphase

47. Anaphase

48. Telophase

49. Interphase

50. Prophase

51. Metaphase

52. Anaphase

53. Telophase

55. Control of Cell Division
G1 Checkpoint
Enzymes will kick in if cell is large enough and conditions are favorable to reproduce
G2 Checkpoint
DNA repair enzymes will fix any mutations, if checkpoint is passed mitosis will occur
Mitosis checkpoint – if all is correct, the 2 daughter cells will enter G1 phase and start over again

56. Uncontrolled
Mitosis is
cancer.

57. When Control is Lost
Enzyme proteins are not functioning properly causing cell to reproduce out of control
Could cause cancer
Cancer cells do not respond to body’s signals that control mechanisms

58. Some Cancer Statistics:
1 in 7 people will have some form of cancer in their lifetimes.
1 in 8 women will get breast cancer.
Lung cancer is the leading cause of cancer deaths in the U.S.
There are approx. ½ million deaths from cancer in the U.S. per year.

59. Compare/Contrast

60. How else can our body control cancer?