Organelles & compartmentalization

• Cell Organelles


  Compartmentalised cell structure
• Eukaryotic cells have a more complex ultrastructure than prokaryotic cells
• Cytoplasm of eukaryotic cells

  Divided up into membrane-bound compartments called organelles
• Organelles


  Compartments bound by a single or double membrane
• Structures not considered organelles

  • Cell wall
  • Cytoskeleton
  • Cytoplasm
• Eukaryotic cell organelles


  • The nucleus
  • Vesicles
  • Ribosomes
  • The plasma membrane
• Compartmentalization of the cell

  • Allows enzymes and substrates to be localized and therefore available at higher concentrations
  • Allows damaging substances to be kept separated, e.g. digestive enzymes are stored in lysosomes so they do not digest the cell
  • Allows optimal conditions to be maintained for certain processes e.g. optimal pH for digestive enzymes
• The numbers and location of organelles are to be altered depending on the requirements of the cell
• Organelle Adaptations

  • In complex cells organelles can become specializedan for specific functions
  • These specialized organelles have specific adaptations to help them carry out their functions
  • For example, the structure of an organelle is adapted to help it carry out its function (this is why each organelle looks very different from each other)
  • The separation of organelles from the rest of the cell, via a membrane (sometimes double), is important as it allows the organelle to carry out its own chemical reactions without interference from the rest of the cell
• • Nucleus, Rough ER, Smooth ER, Golgi Apparatus, Lysosome, Mitochondrion, Free Ribosomes, Chloroplast, Vacuole, Vesicles, Centrioles, Cilia, Flagella, Cell Membrane, Microvilli are all organelles in cells that are adapted to perform specific functions.
• Nucleus


  Contains genetic material, regulates cell activities
• Mitochondria


  Site of cellular respiration, generating ATP
• Endoplasmic Reticulum (ER)


  Involved in protein synthesis, lipid synthesis, and detoxification
• Ribosomes


  Site of protein synthesis
• Lysosomes


  Contain digestive enzymes, break down and recycle cellular waste
• Golgi Apparatus


  Processes and packages proteins and lipids for secretion
• Plasma Membrane


  Semi-permeable barrier, regulates what enters/exits the cell
• Centrioles


  Involved in spindle formation during cell division
• Cytoskeleton


  Composed of microtubules, microfilaments, and intermediate filaments; plays a role in cell shape, movement, and division
• Mitosis


  A type of cell division resulting in two daughter cells each with the same number and kind of chromosomes as the parent nucleus
• Interphase


  Cell grows, replicates DNA, and prepares for cell division
• Prophase


  Chromatin condenses into visible chromosomes, nucleolus disappears, and spindle fibers form
• Metaphase


  Chromosomes align at the center of the cell, attached to the spindle fibers
• Anaphase


  Sister chromatids separate, moving to opposite poles
• Telophase


  Chromosomes decondense into chromatin, nuclei reform around each set of chromosomes
• Cytokinesis


  In animal cells, cytoplasm divides, and the cell splits
• Cell Plate Formation


  In plant cells, a cell plate forms, and the cell divides
• Spindle Fibers


  Regulate chromosome separation and movement
• Centrioles


  Help form spindle fibers and separate chromosomes
• Cell Compartmentalization


  The process by which cells separate their internal functions into different regions or compartments
• Plasma Membrane


  Semi-permeable barrier regulating what enters and exits the cell
• Water Potential


  The potential energy of water molecules in a solution
• Osmosis


  The movement of water molecules through a selectively permeable membrane due to a concentration gradient
• Cell Specialization


  The process of cells adapting to specific functions or environments
• Structural Cell Specialization


  C cells with unique shapes or structures for specific functions
• Functional Cell Specialization


  C cells with specialized functions for specific tasks
• Epithelial Cell Specialization


  C cells that maintain tissue integrity and form barriers
• Cell Structure


  The complex organization of a cell, composed of various organelles, membranes, and cytoplasm
• Plasma Membrane


  A semi-permeable membrane surrounding the cell, regulating the movement of materials
• Cytoplasm


  The jelly-like substance inside the cell, containing organelles and dissolved substances