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Isaiah 61:1-3

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;

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Isaiah 61:1-3

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  1. Isaiah 61:1-3 1The 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. Mitosisand 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. Egg 1n Haploid nucleus Sperm 1n Haploid nucleus Fertilization Results In A Diploid Zygote

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

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

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

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

  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. Surface 24 cm2/ volume 8 cm3 = 3 1 cm 2 cm Surface 6 cm2/ volume 1cm3= 6 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)

  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. 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 S Gap 2 - Final preparation for division G1 G2 M Mitosis - Cell division The Cell Lifecycle

  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. S G2 G1 Interphase M Stages Of 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

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

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

  22. Histone proteins 2 nm Packaging DNA T G A Histone octomer C GC TA GC CG TA AT AT CG B DNA Helix GC TA

  23. 11 nm Histone proteins Nucleosome 2 nm Packaging DNA T G A Histone octomer C GC TA GC CG TA AT AT CG B DNA Helix GC TA

  24. GC CG TA AT AT CG GC TA Packaging DNA

  25. GC CG TA AT AT CG GC TA Packaging DNA

  26. 11 nm GC CG TA AT 30 nm 200 nm AT CG GC TA Protein scaffold Packaging DNA “Beads on a string” Looped Domains Tight helical fiber

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

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

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

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

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

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

  41. The End

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