Cells

• 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 like glycoproteins, secretory enzymes, carbohydrates, lipids
• Lysosomes


  Bags of digestive enzymes involved in phagocytosis and exocytosis
• 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
• Key differences between prokaryotic and eukaryotic cells

  • Prokaryotes are much smaller
  • Prokaryotes lack membrane-bound organelles
  • Prokaryotes have a single loop of DNA
  • Prokaryotes have 70S ribosomes
  • Prokaryotes have a cell wall
  • Prokaryotes may have plasmids and flagella
• Viruses


  Acellular and non-living, consist of genetic material, capsid, and attachment proteins, replicate inside host cells
• Methods of studying cells

  • Microscopes (optical and electron)
  • Cell fractionation and ultracentrifugation
• 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
• Cell fractionation


  1. Homogenization to break open cells

  2. Ultracentrifugation to isolate organelles by density
• Cell fractionation requires cold, isotonic, buffered conditions
• Order of organelle isolation by density


  • Nuclei
  • Chloroplasts and mitochondria
  • Lysosomes and ER
  • Ribosomes
• Eukaryotic cells divide by mitosis or meiosis, prokaryotic cells replicate by binary fission, viruses replicate inside host cells
• Cell cycle


  Includes interphase (G1, S, G2) and cell division (mitosis or meiosis)
• Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase
• Mitosis produces genetically identical cells in a single round of division
• 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


  • Only one round of division
  • Genetically identical cells are created
  • Cells are diploid (two copies of every chromosome)
  • Used for growth and repair
• Clonal expansion of B cells is an example of growth through mitosis
• Prophase


  1. Chromosomes condense and become visible

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

  1. Chromosomes line up along the equator

  2. Spindle fibers attach to centromeres and chromatids
• Anaphase


  Spindle fibers retract, pulling chromatids to opposite poles
• Telophase


  1. Chromosomes at poles become longer and thinner

  2. Spindle fibers disintegrate

  3. Nucleus reforms
• Mitotic index


  Percentage of cells in a population undergoing mitosis