1. Isaiah 61:1-3
1 The Spirit of the Lord GOD is upon me; because the LORD hath anointed me to preach good tidings unto the meek; he hath sent me to bind up the brokenhearted, to proclaim liberty to the captives, and the opening of the prison to them that are bound;
2 To proclaim the acceptable year of the LORD, and the day of vengeance of our God; to comfort all that mourn;
3 To appoint unto them that mourn in Zion, to give unto them beauty for ashes, the oil of joy for mourning, the garment of praise for the spirit of heaviness; that they might be called trees of righteousness, the planting of the LORD, that he might be glorified.

2. Mitosis and Meiosis
Timothy G. Standish, Ph. D.

3. Mitosis: In The Beginning One
Most of the organisms we see started out as one cell
Humans start out as a single cell, the zygote, formed by uniting a sperm and egg
The zygote divides to make approximately one trillion cells
During the process of dividing, cells become specialized to function in the various tissues and organs of the body
Mitosis is the process of cell division in eukaryotic cells

4. Fertilization Results In A Diploid Zygote
Egg 1n
Haploid
nucleus
Sperm 1n
Haploid
nucleus

5. Fertilization Results In A Diploid Zygote
Egg 1n
Haploid
nucleus
Sperm 1n
Haploid
nucleus

6. Fertilization Results In A Diploid Zygote
Egg 1n
Haploid
nucleus
Haploid
nucleus
Sperm 1n

7. Fertilization Results In A Diploid Zygote
Egg 1n
Haploid
nucleus
Haploid
nucleus
Sperm 1n

8. From Zygote to Embryo
Zygote 2n
Zygote 2n

9. From Zygote to Embryo
Cleavage

10. From Zygote to Embryo
Cleavage

11. From Zygote to Embryo
Cleavage

12. From Zygote to Embryo
Cleavage

13. From Zygote to Embryo
Morula

14. Why Cells Must Divide
In multicelled organisms (like humans) cells specialize for specific functions thus the original cells must divide to produce different kinds of cells
Cells can only take in nutrients and excrete waste products over the surface of the membrane that surrounds them. The surface to volume ratio decreases with the square of the volume (unless special accommodations are made)
1 cm
Surface 6 cm2/
volume 1cm3= 6
2 cm
Surface 24 cm2/
volume 8 cm3 = 3

15. The Cell Lifecycle
The cell lifecycle is well defined and can be divided into four stages:
Gap 1 (G1) - The growth phase in which most cells are found most of the time
Synthesis (S) - During which new DNA is synthesized
Gap 2 (G2) - The period during which no transcription or translation occurs and final preparations for division are made
Mitosis - Cell division

16. The Cell Lifecycle G1 S G2 M
Gap 1 - Doubling of cell size. Regular cellular activities. Transcription and translation etc.
Synthesis of DNA - Regular cell activities cease and a copy of all nuclear DNA is made G1 S G2
Gap 2 - Final preparation for division M
Mitosis - Cell division

17. Stages Of Mitosis
During mitosis an exact copy of the genetic material in the “mother” cell must be distributed to each “daughter” cell
Each stage of mitosis is designed to achieve equal and exact distribution of the genetic material which has been copied during the S phase of the cell cycle

18. Stages Of Interphase Interphase
Interphase - The in-between stage - Originally interphase was thought to be a resting stage. Now we know that this is the stage most cells spend their time in as they do the things cells do including, if they are preparing to divide, growing and replicating their DNA
Interphase G1 M G2 S

19. Stages Of Mitosis
Prophase - The beginning phase - DNA which was unraveled and spread all over the nucleus is condensed and packaged
Metaphase - Middle stage - Condensed chromosomes line up along the equator of the cell
Anaphase - One copy of each chromosome moves to each pole of the cell
Telophase - End stage - New nuclear membranes are formed around the chromosomes and cytokinesis (cytoplasm division) occurs resulting in two daughter cells

20. Stages Of Mitosis Mother cell Nucleus with un-condensed chromosomes
Interphase
Nucleus with un-condensed chromosomes
Prophase
Condensed chromosomes
Equator of the cell
Metaphase
Metaphase plate
Disappearing nuclear membrane
Poles of the cell
Anaphase
Two daughter cells
Mitotic spindle
Telophase

21. Packaging DNA T G A Histone C octomer Histone proteins 2 nm
T A
G C
C G TA T A G C
C G
G C
T A
A T
Packaging DNA
Histone proteins
Histone
octomer
2 nm
B DNA Helix

22. Packaging DNA T G A Histone C G C octomer Histone proteins 2 nmTA
G C
T A
C G
A T
A T
2 nm
C G
B DNA Helix
G C
T A

23. Packaging DNA T G A 11 nm Histone C G C octomer Histone proteinsTA
G C
T A
C G
Nucleosome
A T
A T
2 nm
C G
B DNA Helix
G C
T A

24. Packaging DNA
A T
T A
G C
C G
C G
G C
T A
A T

25. Packaging DNA
A T
T A
G C
C G
C G
G C
T A
A T

26. Packaging DNA “Beads on a string” 11 nm 30 nm Looped Domains 200 nm
A T
T A
G C
C G
C G
G C
T A
A T
30 nm
Looped Domains
200 nm
Tight helical fiber
Protein scaffold

27. Packaging DNA 11 nm 30 nm 200 nm 2 nm 700 nm Metaphase Chromosome
Looped Domains
Nucleosomes
B DNA Helix
Tight helical fiber
700 nm G C A T
Metaphase Chromosome
Protein scaffold

28. Chromosomes, Chromatids and Centromeres
A packaged chromosome
Chromatid
Identical
chromatid
Replication
Anaphase
Chromosome arm
Two identical chromosomes
Centromere
Chromosome arm

29. Chromosome Morphology
Chromosomes can be distinguished on the basis of size and the relative location of centromeres.
Metacentric
Submetacentric
Acrocentric
Telocentric
Chromosome arm
Centromere
p arm
petite
q arm

30. Controlling The Cell Cycle
CDC Mutants - Cell Division Cycle mutants helped elucidate genetic control points of the cell cycle
Three major checkpoints controlled by Cyclin dependant kinase (Cdk) proteins which add phosphates to cyclin proteins changing their activity:
G1S - Monitors cell size and checks for DNA damage
G2M - Ensures physiological conditions are right for division, including completion of DNA replication and any necessary repair
M - Checks for successful formation of the mitotic spindle and attachment to the kinetochores

31. p53

32. Meiosis: In The Beginning Two
Humans and many other complex multi-celled organisms incorporate genetic recombination in their reproduction
Reproduction in which there is a re-mixing of the genetic material is called sexual reproduction
Two cells, a sperm and an egg, unite to form a zygote, the single cell from which the organism develops
Meiosis is the process of producing sperm and eggs (gametes)

33. Gametes Are Haploid
Gametes must have half the genetic material of a normal cell
If the genetic material in the gametes were not halved, when they combined the zygote would have more genetic material than the parents
Meiosis is specialized cell division resulting in cells with half the genetic material of the parents
Gametes have exactly one set of chromosomes, this state is called haploid (1n)
Regular cells have two sets of chromosomes, this state is called diploid (2n)

34. Stages Of Meiosis
Meiosis resembles mitosis except that it is actually two divisions not one
These divisions are called Meiosis I and Meiosis II
Meiosis I results in haploid cells with chromosomes made up of two chromotids
Meiosis II is essentially mitosis on haploid cells
Stages of meiosis resemble mitosis with two critical differences: the first in Prophase I and the second in Metaphase I

35. Stages Of Meiosis - Meiosis I
Prophase I - The beginning phase -
DNA which was unraveled and spread all over the nucleus is condensed and packaged
Homologous chromosomes (each made of two identical chromatids) come together and form tetrads (4 chromatids)
Crossing over, in which chromatids within tetrads exchange genetic material, occurs
Metaphase I - Middle stage - Tetrads line up along the equator of the cell

36. Stages Of Meiosis - Meiosis I
Anaphase I - One copy of each chromosome still composed of two chromatids moves to each pole of the cell
Telophase I - End stage - New nuclear membranes are formed around the chromosomes and cytokinesis (cytoplasm division) occurs resulting in two haploid daughter cells

37. Stages Of Meiosis - Meiosis II
Prophase II - Cells do not typically go into interphase between Meiosis I and II, thus chromosomes are already condensed
Metaphase II - Chromosomes line up at the equator of the two haploid cells produced in Meiosis I
Anaphase II - Chromosomes made up of two chromatids split to make chromosomes with one chromatid which migrate to the poles of the cells
Telophase II - Cytokinesis and reformation of the nuclear membrane in haploid cells each with one set of chromosomes made of one chromatid

38. Stages Of Meiosis: Meiosis I
Interphase
Mother cell
Prophase I:
Condensing Chromosomes
Prophase I:
Tetrad formation/
crossing over
Metaphase I
Anaphase I
Telophase I
Meiosis II

39. Stages Of Meiosis: Meiosis II
The products of meiosis are 4 haploid cells each with a unique set of chromosomes.
Telophase I
Prophase II
Metaphase II
The products of mitosis are 2 diploid cells with identical chromosomes.
Anaphase II
Telophase II

40. Crossing Over Prophase I: Metaphase I Anaphase I Telophase I
Tetrad formation/
crossing over
Metaphase I
Anaphase I
Telophase I
Because of crossing over, every gamete receives a unique set of genetic information.
Telophase II

41. The
End