1 / 56

Cell Reproduction

Cell Reproduction. Stem Cell Shakes In The News. Dividing Nuclear Material. Cells must accurately separate genetic material during cell reproduction Methods Mitosis Meiosis. Mitosis. Produces two cells identical to original cell Each cell has full DNA complement

davidmedina
Download Presentation

Cell Reproduction

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. Cell Reproduction

  2. Stem Cell ShakesIn The News

  3. Dividing Nuclear Material • Cells must accurately separate genetic material during cell reproduction • Methods • Mitosis • Meiosis

  4. Mitosis • Produces two cells identical to original cell • Each cell has full DNA complement • Used for growth and repair of somatic (body) cells

  5. Meiosis • Produces 4 cells that are not identical to parent cell • Daughter cells have half genetic complement • Produces gametes (sex cells)

  6. Animal Life Cycle • Egg = female gamete • Sperm = male gamete • Zygote • Fusion of egg & sperm • Full complement of genetic material

  7. Diploid Cells (2N) • Full genetic complement • 23 pair of chromosomes in humans

  8. Haploid Cells (N) • Produced during meiosis • Contain only one set of chromosomes • Reduction of chromosomes allows for combination to form diploid zygote

  9. Fertilization • One sex cell from each parent joins • Creates diploid zygote • Process is called sexual reproduction

  10. Animal Life Cycles • Diploid phase dominates • Gametes live hours to days

  11. Plant Life Cycles • Most have multicellular haploid phase • Phase names • Gametophyte = haploid • Sporophyte = diploid • Either phase can dominate, depending on plant type

  12. Single Cell Eukaryote Reproduction • Reproduce by mitosis • Called asexual reproduction • Produced two identical organisms

  13. Asexual Reproduction • All single cell eukaryotes • Some plants • Some animals

  14. Cell Cycle (Life Cycle)

  15. Interphase • Most of cell cycle • Cell grows • Organelles replicated • DNA replicated • Readies for mitosis • Condenses DNA

  16. G1 Interphase • Cell growth-doubles in size • Carries out its normal life functions

  17. S Interphase • DNA replicated • At the end of this phase, the cell will contain two identical copies of heredity info.

  18. G2 Interphase • DNA condenses into chromosomes • Strands = sister chromatids • Chromatids connected by centromere

  19. Stages of Mitosis • Prophase • Metaphase • Anaphase • Telophase

  20. Prophase • Chromosomes shorten & thicken • Nucleolus & nuclear envelope disappears

  21. Prophase • Spindle fibers formed from microtubules • Microtubules surround microtubule-organizing center (centrosome) • Chromosomes attach to spindle fibers at kinetochore

  22. Metaphase • Pairs of sister chromatids align at center • Forms metaphase plate

  23. Anaphase • Chromatids separate at centromere • Chromatids pulled in two directions • Chromosomes move toward poles • Equally divides hereditary material

  24. Telophase • Cell readied for division (cytokinesis) • Spindle fibers disassemble • Nuclear envelope reforms • Nucleolus reappears

  25. Cytokinesis • Cell division after mitosis • Cleavage furrow enlarges

  26. Animal Cytokinesis • Cell pinched in two (lack cell walls) • Pinching by microfilaments contracting

  27. Plant Cytokinesis • New cell wall must be laid down • Cell plate forms (Golgi Complex)

  28. Mitosis

  29. Cancer • Deregulation of cell cycle • Loss of control of mitosis • Result of mutation • Over 200 types of cancer exists • Number of cancer cases will double by 2050, as an increasing proportion of U.S. population reaches older ages

  30. United States Cancer Death Rates

  31. Characteristics of Cancer(no matter what type) • Uncontrolled cell growth- most significant characteristic of all cancer cells • Loss of cell differentiation (specialization) • Invasion of normal tissues, occupying space in which normal cells would otherwise reside • Metastasis or spread to multiple sites

  32. Stages of Cancer 1. Initiation 2.Promotion 3.Progression

  33. Initiation of Cancer(Transformation) • Series of gene mutations damages DNA • Proto-oncogenes become oncogenes (“on” switches for tumors or masses) • Usually additional mutations are needed • Affect tumor suppressor genes, ”off” switches • These genes are inactivated, allowing cancerous growth • Initiation does not directly result in cancer, it results in a precancerous cell. • Heredity acts only as an initiator, not a promoter

  34. Promotion of Cancer • Cells are stimulated to grow & divide when they normally would not. • It is a gradual process, unlike initiation • Carcinogens – agents that both initiate & promote cancer • Viruses • Chemicals • Radiation • Benign cells • Masses of partially transformed cells, confined & encapsulated • Cells exhibit dysplasia-growth patterns char. of cancer cells

  35. Normal Cells Dysplastic Cells

  36. Progression of Cancer • Cells become less differentiated • Cells invade other tissue • Move to other areas of the body • Called malignant cells

  37. Meiosis • Chromosome number halved • 2N  N • Required for sexual reproduction • Starts with diploid parents

  38. Homologues • Homologous chromosomes • 2 chromosomes, same linear gene sequence • corresponding genes on the 2 chromosomes are called alleles, alternative forms of same gene

  39. Process of Meiosis Two stages: Meiosis I Meiosis II Results in 4 haploid daughter cells

  40. Meiosis I • Pairs line up = synapsis • crossing over begins • Splitting homologous pairs, tetrads

  41. Meiosis I • Cross over – non sister chromosomes may cross over one another • Chromatids may exchange segments

  42. Stages of Meiosis I

  43. Interkinesis • Interphase-like period • Between meiosis I and meiosis II • No DNA replication

More Related