Review for Cells

History of MicroscopyHooke observes first cells (cork) -1665Leeuwenhoek – animalcules (living cells)- 1674

Jump to late 1830sSchleiden – plants made of cells 1838Schwann – animals made of cells 1839Brown - nucleusVirchow – Cells make more cells – 1850s

RESULT: THE CELL THEORY

Cell TheoryAll 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 microscopesLight 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 MicroscopesScanning

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 microscopeInverts and flips the image

Move slide right, appears to move leftMove 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 DiversityDifferent shapes and sizes due to different

functionsForm 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 TypesProkaryotes

Only single cellsVery smallNo membrane bound organellesRibosomes, membrane, cell wall, cytoplasm,

nucleic acidsThree major shapes: bacillus, spirillium, coccus

Cell TypesEukaryotes

One t0 billions of cellsSimple to very complexAll contain a nucleus (one or more)All kingdoms except ProkaryotePlants have chloroplasts, cell walls, large

central vacuoleAnimals have small vacuoles, centrioles, no cell

wall10-100x bigger than prokaryotes

Cell Organelles (see picturesLook at diagrams provided and the six

“processes”. Trace the process creating a flow chart that covers key points.

Make a proteinEndocytosis and exocytosisEnergy Cell divisionMovement of cellsMolecules, ions and types of transport

Cell TransportPhospholipids, Proteins, carbohydrates,

cholesterol

Nucleus, cytoplasm, ER, Golgi

Cholesterol: flexibilityCarbohydrates: identification tags

Membrane FunctionCO2, H2O, O2, small non-polar compounds ,

N2Small, non-polar

Membrane proteins – very specific for particular moleculesAmino acids, glucose, ions

Charged, larger

Energy is needed when molecules or ions need to move AGAINST the gradient (from low to high)

Membrane FunctionNo 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 membranePassive transport

Diffusion – membrane NOT required (food coloring, perfume)

Facilitated Diffusion (protein mediate)Osmosis

Active transportProtein mediated Vesicle mediate

Osmosis and TonicityOsmosis 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 tonicitiesWhat 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 transportVesicles move many molecules at a time either

out of the cell or into the cellExocytosis –OUT of the cellExample: 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!