Section 2

• Key eukaryotic cell organelles

  • Nucleus
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Mitochondria
  • Ribosomes
  • Vacuole
  • Chloroplasts
  • Cell wall
  • Plasma membrane
• Nucleus


  Where DNA replication occurs and mRNA is made, contains the genetic code
• Nucleolus


  Site of rRNA production and ribosome assembly
• Rough endoplasmic reticulum (RER)


  Site of protein synthesis due to ribosomes on the outside
• Smooth endoplasmic reticulum (SER)


  Site of lipid and carbohydrate synthesis and storage
• Golgi apparatus


  Modifies, packages and distributes molecules
• Lysosomes


  Bags of digestive enzymes involved in phagocytosis
• Mitochondria


  Site of aerobic respiration and ATP production
• Ribosomes


  Site of protein synthesis, found in both prokaryotic and eukaryotic cells
• Vacuole


  Fluid-filled structure that provides support and stores substances in plant cells
• Chloroplasts


  Site of photosynthesis in plant cells
• Cell wall


  Provides structural strength and prevents bursting in plant and fungal cells
• Plasma membrane


  Controls what can enter and exit the cell
• Prokaryotic cells are much smaller, lack membrane-bound organelles, and have a single loop of DNA instead of a nucleus
• Viruses are acellular and non-living, consisting of genetic material, a capsid, and attachment proteins
• Viruses replicate inside host cells
• Methods of studying cells

  • Microscopes
  • Cell fractionation
  • Ultra-centrifugation
• Magnification


  How many times larger the image is compared to the object
• Resolution


  Minimum distance between two objects where they can still be viewed as separate
• Optical microscopes


  • Use a beam of light, have lower resolution, can view living samples, produce color images
• Electron microscopes


  • Use a beam of electrons, have higher resolution, cannot view living samples, produce black and white images
• Cell fractionation


  1. Cells are broken open in a cold, isotonic, buffered solution

  2. Homogenization to break open cells

  3. Ultra-centrifugation to isolate organelles by density
• Eukaryotic cells divide by mitosis or meiosis, while prokaryotic cells replicate by binary fission
• Viruses do not undergo cell division, but replicate inside host cells
• Mitosis


  • One round of division, produces genetically identical cells, diploid cells
• Host cell

  The cell that uses the genetic material to replicate the virus particle
• Eukaryotic cell cycle

  1. Interphase

  2. Mitosis
• Interphase


  The longest stage of the cell cycle, includes G1, S, and G2
• G1

  Cell increases in size, organelles double
• S phase

  DNA replication happens
• G2

  Further growth, preparation for mitosis, error check stage
• Nuclear division

  Mitosis or meiosis
• Cytokinesis


  Cytoplasm divides to create two new cells
• Mitosis

  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase
• Mitosis

  • Only one round of division
  • Genetically identical cells created
  • Cells are diploid (two copies of every chromosome)
  • Used for growth and repair
• Specific example of mitosis

  • Clonal expansion of B cells
• Prophase

  1. Chromosomes condense and become visible

  2. Centriole pairs move to opposite poles, create spindle fibers
• Metaphase

  1. Chromosomes line up in single file along the equator

  2. Spindle fibers attach to centromeres and chromatids
• Anaphase


  1. Spindle fibers retract, pulling chromatids to opposite poles

  2. Centromeres divide, chromatids become chromosomes
• Telophase


  1. Chromosomes at each pole become longer and thinner

  2. Spindle fibers disintegrate

  3. Nucleus reforms