L4 BIO

• Eukaryotic cells


  "True cells"
• Types of cells


  • Somatic cells
  • Sex cells
• Somatic cells


  • Cells that make your organs and tissues
  • All cells in the body except reproductive cells
• Sex cells


  • Only cells that are not somatic
  • Sperm and egg (gametes)
• Cell division


  • A single cell divides into two or more daughter cells
  • Essential for the growth, repair, and reproduction of living organisms
• Types of cell division

  • Mitosis
  • Meiosis
• Mitosis


  • Two identical daughter cells
  • Essential for growth and repair in multicellular organisms
  • Asexual reproduction in some single-celled organisms
• Meiosis


  • 4 daughter cells each with half the number of chromosomes of the parent cell
  • Critical for sexual reproduction
• Cell cycle


  Series of events that cells go through as they grow and divide
• Phases of the cell cycle

  • Interphase
  • G1 Phase
  • S Phase
  • G2 Phase
  • M Phase
• Interphase


  • Period of growth that occurs between cell divisions
  • Cell spends most of its life in this phase
• G1 Phase


  • Takes up to 4 hours
  • Cell grows
  • Synthesizes new proteins and organelles (cell develops)
• S Phase


  • Takes up to 5 hrs
  • DNA replication
  • Chromosomes are replicated; has two sister chromatids
• G2 Phase


  • Takes up to 9 hrs
  • Organelles and molecules required for cell division are produced
  • Once complete, the cell is ready for reproduction
• M Phase


  A nuclear division followed by a cytoplasm division
• Characteristics of mitosis


  • Produces two Genetically Identical daughter cells from a single parent cell
  • Major purpose is for growth and to replace worn-out cells
  • Mitosis occurs only in somatic cells
  • There is no reduction in the number of chromosomes during mitosis
• Importance of mitosis


  • Growth and development
  • Repair and maintenance
  • Asexual reproduction
• Cell


  Basic unit of life
• Split chromosome


  Separation of the chromosome
• Chromosome


  Structure found in the nucleus of cells that carries genetic information in the form of DNA
• Centrosome


  • Small organelle found in eukaryotic cells
  • Functions as a microtubule-organizing center
  • Fanlike microtubule structure that helps separate the chromosomes
• Spindle fibers


  Microtubules that separate the chromosomes into two daughter cells
• Centrioles


  • Cylindrical organelles found in eukaryotic cells
  • Involved in the organization of cell division
• Stages of mitosis


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Prophase


  • First and longest phase
  • Chromatin in the nucleus condenses into visible chromosomes
  • Centrioles separate and take up positions on opposite sides of the nucleus and lie in a region called the centrosome
  • Disappearance of nucleus membrane and nucleolus
• Metaphase


  • Chromosomes line up along the equator of the cell, called the metaphase plate
  • Shortest phase
• Anaphase


  • Sister chromatids of each replicated chromosome separate and are pulled towards opposite poles
  • Formation of two identical sets of chromosomes
• Telophase


  • Chromosomes reach the opposite poles of the cell
  • Formation of nuclear membrane and nucleolus
  • Spindle fibers disassemble and the cell begins to prepare for cytokinesis
• Cytokinesis


  • Cytoplasm division
  • In animal cells, chromosomes reach the opposite poles of the cell, contracting and pinching the cell membrane until the cell is divided into two separate cells
  • In plant cells, a structure called the cell plate forms along the equator of the cell, dividing the cell into two separate daughter cells