Biology

• Key eukaryotic cell organelles


  • Nucleus
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Mitochondria
  • Ribosomes
  • Vacuoles
  • Chloroplasts
  • Cell wall
  • Plasma membrane
• Prokaryotic cells


  • Smaller size
  • No membrane-bound organelles
  • Single loop of DNA
  • 70S ribosomes
  • May have cell wall, capsule, flagella
• Viruses


  • Acellular and non-living
  • Consist of genetic material, capsid, and attachment/envelope proteins
• Prokaryotes(organelles all have)


  • Have ribosomes though because ribosomes are not membrane-bound but they have the 70s size ribosomes
  • They don't have a nucleus because that is a membrane-bound organelle so instead their DNA will just be as a single Loop which is free within the cytoplasm
  • They do have a cell wall and that is made up of murin
• Viruses


  • Acellular and non-living
  • The structure of virus particles consists of genetic material, capsid, and attachment proteins (envelope proteins)
• Viruses replicate inside of host cells and that is why it's very difficult to destroy them because you would have to destroy the host cell to be able to destroy the virus
• Methods of studying cells


  • Microscopes
  • Cell fractionation
• Magnification


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

  A measure of a microscopes ability to distinguish between two points that are close together on an object.
• Types of microscopes


  • Optical microscopes
  • Transmission electron microscopes
  • Scanning electron microscopes
• Optical microscopes


  Use a beam of light to create the image
• Electron microscopes


  Use a beam of electrons to create the image
• Optical microscopes


  Have lower resolution due to the longer wavelength of light
• Electron microscopes


  Have higher resolution due to the shorter wavelength of electrons
• Transmission electron microscope


  Uses extremely thin specimens and the electron beam passes through the specimen
• Scanning electron microscope


  Creates 3D images by scanning the surface of the specimen with the electron beam
• Calculating magnification


  Image size = Actual size x Magnification
• Eyepiece graticule


  A scale within the optical microscope that can be used to measure the size of objects
• 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 based on density
• Nuclei are the most dense organelles, followed by chloroplasts and mitochondria, then lysosomes, endoplasmic reticulum, and finally ribosomes
• Stages of the eukaryotic cell cycle


  • Interphase (G1, S, G2)
  • Mitosis
  • Cytokinesis
• Prokaryotic cells replicate by binary fission
• Viruses do not undergo cell division, but they do replicate inside host cells
• Interphase


  The longest stage of the cell cycle, including cell growth and DNA replication
• Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase
• What does mitosis produce?

  Produces genetically identical diploid cells, used for growth and repair
• Mitotic index


  The percentage of cells in a population that are undergoing mitosis
• Fluid mosaic model


  The structure of cell membranes, composed of a phospholipid bilayer with embedded proteins
• Peripheral proteins


  Proteins on the outside of the membrane, providing mechanical support or connecting to carbohydrates
• Integral proteins


  Proteins that span the membrane, acting as carriers or channels
• Partially permeable membrane


  Only allows certain molecules to pass through by diffusion, facilitated diffusion, or active transport
• Simple diffusion


  The net movement of molecules from high to low concentration, without requiring energy
• Facilitated diffusion


  The movement of molecules through membrane proteins from high to low concentration, without requiring energy
• Osmosis


  The movement of water from high to low water potential across a partially permeable membrane
• Osmotic conditions


  • Isotonic
  • Hypotonic
  • Hypertonic
• Osmosis


  The movement of water from an area of higher water potential to an area of lower water potential across a partially permeable membrane
• Water potential


  The pressure created by water molecules, measured in kilopascals
• Pure water or distilled water has a water potential of zero</b>
• When solutes are dissolved in water, the water potential will be negative and the more negative the water potential, the more solutes there must be dissolved in it
• Key terms linked to osmosis


  • Isotonic
  • Hypotonic
  • Hypertonic