Chapter 4

  • the microscope was invented in the 17th century (1600’s)
  • Robert Hooke discovered cells in 1665
  • All living things are made of cells (cell theory)

  Electron microscope

  • They use a beam of electrons instead of light
  • Allows greater magnification
  • Reveals cellular details

  Natural Laws limit cell size

  • A cell must e large enough to house the parts it needs to survive and reproduce
  • The maximum size of a cel is limited by the amount of surface needed to obtain nutrients from the environment and dispose of wastes
  • A small cell has a greater ratio of a surface area to volume than a large cell of teh same shape

  Prokaryotic ceills

  • Small; simple
  • Do not have a nucleus bound membrane
  • Have Nucleoid

  Eukaryotic cells

  • These are larger and more complex
  • Has a nucleus
  • The cytoplasm (jelly filling) contains organelles
  • Many organelles have membranes as boundaries

  Organelles of the endomembrane system

  • Divides the cell into compartments
  • 1. Nucleus 2. Smooth Endoplasmic reticulum 3. Rough Endoplasmic reticulum 4. Golgi bodies 5. Lysosomes 6. Vacuoles

  Nucleus is the cells genetic control center

  • Contains the DNA that directs the cells activities
  • Chromatin- long fibers of DNA attached to proteins
  • Nucleolus- where ribosomes are made

  Rough Endoplasmic reticulum

  • Manufactures membranes
  • Ribosomes on surface produce proteins

  Smooth Endoplasmic reticulum

  • Synthesizes lipids
  • Regulates carbs
  • Calcium storage
  • Drug detoxification

  Golgi bodies finishes/sorts and ships cells

  • Stacks of membranous sacs
  • Receive/modify ER products, then sends them to other organelles or cell membrane
  • Stores proteins

  Lysosomes

  • Contain digestive enzymes
  • Destroys harmful bacteria
  • Recycling center

  Vacuoles

  • Plant cell- large central vacuole
  • The vacuole has lysosomal and storage functions
  • Protists may have contractile vacuole which pump excess water

  Energy converting organelles

  • Chloroplast are found in plants and some protists
  • Chloroplast convert solar energy to chemical energy in sugars

  Mitochrondria

  • Carry’s cellular respiration
  • Uses chemical energy in food to make ATP for cellular work

  Cytoskeleton

  • Internal skeleton
  • Helps organize its structure/activities
  • Made up of protein fibers

  Eukaryotic cell-surfaces and functions

  • Surface protects, supports and joins cells
  • Plant cells are supported by rigid cell walls made of cellulose
  • Connect by plasmodesmata channels that allow them to share water food and chemical messages

  Animal cells are also commented by junctions

  • Tight junctions can bind cells together into leak proof sheets
  • Anchoring junctions link animal cells
  • Communicating junctions allow substances to flow from cell to cell