1 / 41

LECTURE 9: MITOSIS AND CYTOKINESIS

LECTURE 9: MITOSIS AND CYTOKINESIS. INTRODUCTION. Cell division is accomplished by MITOSIS = division of chromosomes and CYTOKINESIS = division of the cytoplasm Mitosis is the division of somatic cells in which the appropriate number of chromosomes is maintained

kylee-bartlett
Download Presentation

LECTURE 9: MITOSIS AND CYTOKINESIS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LECTURE 9: MITOSIS AND CYTOKINESIS

  2. INTRODUCTION Cell division is accomplished by MITOSIS = division of chromosomes and CYTOKINESIS = division of the cytoplasm Mitosisis the division of somatic cells in which the appropriate number of chromosomes is maintained A somatic cell is a body cell of an organism or a cell that is not involved in reproduction of a new organism. Somatic cells divide to recreate themselves

  3. Cytokinesis is division of the cytoplasm to produce two daughter cells, usually begun during telophase Difference between animals and plants: plants are divided by the formation of a cell plate (=pelat), where animal cells are divided through the formation of a cell cleavage (=belahan). Cell plate materials originate in the golgi complex.

  4. INTRODUCTION When the somatic cell has its complete complement of chromosomes it is said to be in the diploid condition At the end of mitosis daughter cells are diploid Terminology Genome : cell’s genetic information Somatic : body cells Gametes : reproductive cells (sperm and egg cells) Chromosomes : DNA molecules Diploid (2n) : 2 sets of chromosomes Haploid (1n) : 1 set of chromosomes KRT-2008

  5. BASIC PRINCIPLECell Division: Key Roles KRT-2008

  6. Coordination of Mitosis and Cytokinesis Cell Division demands coordination of DNA replication (Mitosis) and division of the cytoplasm (Cytokinesis). Cell Division at cellular level KRT-2008

  7. What’s so important about cell division? The process KRT-2008

  8. PROPHASE INTERPHASE METAPHASE The Knit of Identity - Mitosis Precisely and Evenly Divides Duplicated Chromosomes Precisely dividing the duplicated chromosomes has the consequence of providing each new cell with an identical and complete set of genetic instructions. KRT-2008

  9. Mitosis Precisely and Evenly Divides Duplicated Chromosomes Cytokinesis is the process of cell division and it is distinct and separable from mitosis. KRT-2008

  10. In Animal Cells, a Cleavage Furrow Forms and Separates Daughter Cells KRT-2008 Cleave furrow in a dividing frog cell.

  11. The Plant Cell Wall Forces Cytokinesis to Play by Different Rules KRT-2008

  12. Cancer Transformation Tumor: benign (=jinak) or malignant (=ganas) Metastasis KRT-2008

  13. Cancer Is One Outcome of A Runaway Cell Cycle Licentious division - prostate cancer cells during division. KRT-2008

  14. Chromosome and DNA What is the difference between DNA and Chromosome? What is Karyotype ? KRT-2008

  15. Cell Devision at chromosome level CHROMOSOME DUPLICATION AND SEPERATION KRT-2008

  16. DNA Replication – Simple in Principle, Complicated in Practice Cell Devision at DNA level KRT-2008

  17. duplicated chromosome chromatin DNA is Packaged into Chromosomes DNA in the cell is virtually always associated with proteins. The packaging is impressive – 2 meters of human DNA fit into a sphere about 0.000005 meters in diameter. KRT-2008

  18. The Link Between DNA Replication and Chromosome Duplication KRT-2008

  19. DNA is Condensed into Visible Chromosomes Only For Brief Periods in the Life of a Cell Easily visible chromosomes are apparent perhaps 5% of the time in an actively growing cell and less in a non-growing cell. 95% of the time, chromosomes are like this. KRT-2008

  20. A Karyotype isan arranged picture of chromosomes at their most condensed State A normal human karyotype Note that almost all chromosomes come in homologous pairs. Boy or girl? KRT-2008

  21. The Cell Cycle KRT-2008

  22. From Birth to Rebirth, a Cell Progresses Through Characteristic Stages That Constitute the Cell Cycle In multicellular organisms like us, progress through the cell cycle is carefully regulated. KRT-2008

  23. The Cell Cycle Interphase (90% of cycle) G1 phase~ growth S phase~ synthesis of DNA G2 phase~ preparation for cell division Mitotic phase Mitosis~ nuclear division Cytokinesis~ cytoplasm division INTERPHASE - It is the time between divisions KRT-2008

  24. The Cell Cycle G1 S G2 Mitosis & cytokinesis KRT-2008

  25. Cell Cycle regulation Growth factors Density-dependent inhibition Anchorage (=tempat) dependence KRT-2008

  26. Stages of Mitosis KRT-2008

  27. Mitosis Prophase Prometaphase Metaphase Anaphase Telophase KRT-2008

  28. Mitosis in Action Blue shows DNA, green shows spindle fibers. KRT-2008

  29. Stages of mitosis KRT-2008

  30. Stages of mitosis KRT-2008

  31. PROPHASE, METAPHASE, ANAPHASE,TELOPHASE 1. Prophase: Chromosomes condense and become visible, each Chromosome contains several cm of DNA condensed into 5 – 10 micrometers. During the S Phase each chromosome has been duplicated into a sister chromatid. (A chromotid is one of the two halves of duplicated chromosomes) S Phase = synthesis of DNA

  32. Prometaphase Nuclear membrane fragments Spindle interaction with chromosomes Kinetochore develops KRT-2008

  33. Centrosomes at opposite poles Centromeres are aligned (=disejajarkan) Kinetochores of sister chromatids attached to microtubules (spindle) • 2. Metaphase: • Chromosomes line up along the cell “equator”. • The cell itself condenses and the chromosomes are more clearly visible than during any other phase of mitosis KRT-2008

  34. Paired centromeres separate; sister chromatids liberated Chromosomes move to opposite poles Each pole now has a complete set of chromosomes • 3. Anaphase • is defined as the sister chromatids begin to separate • By now each chromatid is an independent and functional chromosome • The chromosomes are pulled toward opposite poles. Anaphase is complete when a complete set of chromosomes reaches each pole. KRT-2008

  35. 4. Telophase: The final stage of mitosis, chromosomes uncoil (= mengurai) into chomatin threads A nuclear envelope forms around each set of chromosomes, nucleoli appear • Daughter nuclei form • Nuclear envelopes arise • Chromatin becomes less coiled (= menggulung) • Two new nuclei complete mitosis

  36. Structure of a replicatedchromosome KRT-2008

  37. Counting chromosomes and chromatids n = haploid number of chromosomes Example: the humans have 23 different chromosomes (n=23). Diploid cells have 2n chromosome #. Human diploid cells, have 46 chromosomes (2n=46). c = number of chromatids in unreplicated (G1) haploid state. KRT-2008

  38. Replication of achromosome during mitosis KRT-2008

  39. Frequency of mitosis varies between species or even with location within an organism…skin cell versus nerve cells for example, but under similar conditions the length of the cell cycle is constant for a particular type of cell. The rate and frequency of mitosis in a multicelluar organism must be controlled… The cell requires a protein called maturation promoting factor (MPF). Scientists are still learning how MPF works and controls the cell mitosis. CONTROLS ON DIVISION

  40.  Read about the effects of Colchicine and the condition of polypoidy  When mitosis occurs each daughter cell receives exactly the same number and kind of chromosomes as the parent  When a haploid cell undergoes mitosis, two haploid cells are produced.

  41. These are Organisms (living things) KRT-2008

More Related