History of Microscopy
 Hooke observes first cells (cork) -1665
 Leeuwenhoek – animalcules (living cells)- 1674
 Jump to late 1830s
 Schleiden – plants made of cells 1838
 Schwann – animals made of cells 1839
 Brown - nucleus
 Virchow – Cells make more cells – 1850s
 RESULT: THE CELL THEORY
Cell Theory
 All living things made up of one or more cells
 Cells are the basic unit of structure and function in all
living things (no smaller LIVING thing than a cell)
 Cells come from previous cells
Types of microscopes
 Light microscopes
 Stereo

Low magnification, 3D, color, surface structures, light, often used to
compare two things (like bullets…(ballistics)
 Compound
 Magnifies up to 2000, 2D, color, cross sections, light, two lenses
 Electron Microscopes
 Scanning

Magnifies up to 200,000, 3D, surface, electrons, B and W. Shows
surface structures at high resolution
 Transmission
 Magnifies up to 2,000,000, 2D, cross section, electrons, BW, shows
internal cell structures (organelles at high resolution)
Compound microscope
 Inverts and flips the image
 Move slide right, appears to move left
 Move slide up, appears to move down
 High power  smaller field, less light getting in, so
typically need to open up the diaphragm
 Center so that high power (smaller field) will pick up what
you are “viewing”
 Magnification increases size, resolution discriminates
between two points that are very close together.
Cell Diversity
 Different shapes and sizes due to different functions
 Form fits function
 SA/V ratio. Cells can’t get too big or they will die.
When the surface area can’t feed the volume, the cell
divides
Cell Types
 Prokaryotes
 Only single cells
 Very small
 No membrane bound organelles
 Ribosomes, membrane, cell wall, cytoplasm, nucleic
acids
 Three major shapes: bacillus, spirillium, coccus
Cell Types
 Eukaryotes
 One t0 billions of cells
 Simple to very complex
 All contain a nucleus (one or more)
 All kingdoms except Prokaryote
 Plants have chloroplasts, cell walls, large central vacuole
 Animals have small vacuoles, centrioles, no cell wall
 10-100x bigger than prokaryotes
Cell Organelles (see pictures
 Look at diagrams provided and the six “processes”.
Trace the process creating a flow chart that covers key
points.
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



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Make a protein
Endocytosis and exocytosis
Energy
Cell division
Movement of cells
Molecules, ions and types of transport
Cell Transport
 Phospholipids, Proteins, carbohydrates, cholesterol
 Nucleus, cytoplasm, ER, Golgi
 Cholesterol: flexibility
 Carbohydrates: identification tags
Membrane Function
 CO2, H2O, O2, small non-polar compounds , N2
 Small, non-polar
 Membrane proteins – very specific for particular
molecules
 Amino acids, glucose, ions

Charged, larger
 Energy is needed when molecules or ions need to
move AGAINST the gradient (from low to high)
Membrane Function
 No energy needed when flowing with the gradient
(high to low)
 Fluid mosaic: fluid do to movement of molecules
through the lipid bilayer, mosaic due to different
molecules that make up the membrane.
 Semi-permeable, allows some molecules, but not
others, doesn’t discriminate between “good” and “bad”
Transport through the membrane
 Passive transport
 Diffusion – membrane NOT required (food coloring,
perfume)
 Facilitated Diffusion (protein mediate)
 Osmosis
 Active transport
 Protein mediated
 Vesicle mediate
Osmosis and Tonicity
 Osmosis is the movement of water only.
 In our examples, when water moves, the solute does not.
 Tonicity refers to the concentration of SOLUTE (as
compared to another location)
 Hypertonic (high solute, low water)
 Hypotonic (low solute, high water)
 Isotonic ( equal amounts of solute)
 Water moves from hypotonic to hypertonic (low solute 
high solute, or HIGH water, to LOW water
Living cells in different tonicities
 What is the situation in which cells crenate
 What type of cells do this?
 What type of cells undergo cytolysis? Under what
conditions
 Why is high turgor good for plants?
 When can plasmolysis occur, when a solute isn’t
present?
Active Transport vs. Vesicle Transport
 Number of molecules moving at one
time dictates active (few molecules) vs
vesicle (many molecules)
 Both require ATP
 Active transport is through a protein,
against the gradient (low to high)
 Vesicle transport wraps a membrane
around the molecules, creating a “cab”.
doesn’t require a gradient
Vesicle transport
 Vesicles move many molecules at a time either out of the
cell or into the cell
 Exocytosis –OUT of the cell
 Example: hormones, mucus, cell waste
 Endocytosis - into the cell (see next page)
 Phagocytosis – larger particles (proteins, bacteria, etc)
 Pinocytosis – dissolved particles (liquid)
 Hormones are released through exocytosis (too many
molecules
 Phagocytosis – WBC eat bacteria!