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• Cell


  Smallest living unit/Basic unit of life
• Cell functions

  • Protection and support
  • Movement
  • Communication
  • Cell metabolism and energy release
  • Inheritance
• Characteristics of all cells

  • Surrounding membrane (plasma membrane)
  • Protoplasm/cytoplasm – cell contents in thick fluid
  • Organelles – structures for cell function
  • Control center with DNA – serves as a blueprint
• Organelles


  • Cellular machinery
  • Derived from membranes
  • Bacteria-like organelles
• Plasma membrane


  • Outermost component of a cell
  • Contains cell contents
  • Consists of a phospholipid bilayer with embedded proteins
  • Encloses the cytoplasm and forms the boundary between materials outside it
  • Selective barrier that determines what moves into and out of the cell
• Phospholipid bilayers


  Phospholipids – polar head, non-polar tail
• Phospholipid structure

  • Hydrophilic polar head – faces water inside and outside the cell
  • Hydrophobic non-polar tail – water fearing, faces away from water on either side of the membrane
• Small uncharged molecules

  • Gases
  • Oxygen
  • Carbon dioxide
• Lipids-soluble substances


  • Can cross but not in a very fast manner
• Glucose/water-soluble substances

  • Cannot cross
• Charged ions


  • Need to go in and out of the cell
• Membrane proteins

  • Channels or transporters
  • Receptors
  • Glycoproteins
  • Enzymes
• Channels or transporters


  Move molecules in one direction
• Receptors


  Receive signals, like an antenna<|>Recognize certain chemicals
• Glycoproteins


  Identify cell type<|>Responsible for a certain cell to recognize you as a cell of the body
• Enzymes


  Catalyze production of substances
• Cell wall


  • Extra layer, thick wall
  • Found in plants, fungi, and many protists
  • Surrounds plasma membrane
• Cell wall differences

  • Plants – mostly cellulose
  • Fungi – certain chitin
  • Bacteria – cell recognition, cell protection
• Cytoskeleton


  • Filaments and fibers
  • Consists of proteins that support the cell
  • Hold/anchor organelles in place
  • Helps move substances
  • Enable the cell to change shape
• Fiber types

  • Microtubules
  • Intermediate filaments
  • Microfilaments
• Microtubules


  • Lengthy and thickest
  • Spindles and flagella
  • Formed from protein subunits
  • Provide support to the cytoplasm of the cells
  • Assisting in the process of cell division
• Intermediate filaments


  • Medium size
  • Rope-like
  • Tensile strength to withstand pressure
  • Provide mechanical support to the cell
• Microfilaments


  • Smallest
  • Actin, cell movement
  • Formation of contractile ring
  • Structurally support the cytoplasm
• Cytoplasm


  Viscous fluid containing organelles
• Components of cytoplasm

  • Interconnected filaments and fibers
  • Fluid (cytosol)
  • Organelles (not nucleus)
  • Storage substances
• Cilia & flagella

  • Provide motility
  • Cilia – short but multiple
  • Flagella – long but single
• Centrioles and centrosomes


  • Pairs of microtubular structures
  • Play a role in cell division
• Centrioles


  • Always perpendicular to each other
  • Composed of nine triplets of microtubules
• Centrosome


  • Specialized zone/region of the cytoplasm close to the nucleus
  • Containing two centrioles responsible for the formation of spindle fibers
  • Serves as the main microtubule organizing center (MTOC)
• Nucleus


  • Control center of cell
  • Double membrane
  • Contains chromosomes and nucleolus
• Nuclear envelope/nuclear membrane


  • Separates nucleus from rest of cell
  • Double membrane
  • Has pores – getaway of mRNA
• Nucleolus


  • Most cells have two or more
  • Direct synthesis of RNA
  • Forms ribosomes
• Endoplasmic reticulum


  • Helps move substances within cells
  • Network of interconnected membranes
  • Two types: rough and smooth ER
• Rough endoplasmic reticulum


  • Ribosomes attached to surface
  • Manufacture proteins
  • Modify proteins from ribosomes
• Smooth endoplasmic reticulum


  • No attached ribosomes
  • Has enzymes that help build molecules (carbohydrates, lipids)
• Golgi apparatus


  • Involved in synthesis of plant cell wall
  • Final modification, packaging, and shipping station of cell
• Golgi apparatus movements

  1. Molecules come in vesicles

  2. Vesicles fuse with Golgi membrane

  3. Molecules may be modified by Golgi

  4. Molecules pinched-off in separate vesicle

  5. Vesicle leaves Golgi apparatus

  6. Vesicles may combine with plasma membrane to secrete contents
• Lysosomes


  • Suicidal bags
  • Contain digestive enzymes
  • Aid in cell renewal
  • Break down old cell parts
  • Digest invaders
• Peroxisomes


  • Detoxification of hydrogen
  • Breakdown fatty acids, amino acids, and hydrogen peroxide (H2O2)
  • Help in breaking down alcohol in the body
• Vacuoles

  • Membrane bound storage sacs
  • More common in plants (large) than animals
  • Contents: water, food, wastes