History of Microscopy Hooke observes first cells (cork) Leeuwenhoek – animalcules (living cells) 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 x 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. 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!