Chapter 4 - Cell Structure Flashcards
Scientific units
Cm - 1m = 100cm Mm - 1m = 1000mm Um - 1m = 1,000,000um Nm - 1m = 1,000,000,000nm A - 1m = 10,000,000,000A
Fathers of cell biology
Schleiden + Schwann: proposed cell theory. Schleiden= plant cell
Schwann= animal cell
Hooke+Oken: hooke discovered and named cells (cork)
Oken: believed that all living things are made of cells
Virchow: contributed 3rd point in cell theory ( cells divide)
Cell theory
1) all organisms are made of 1 or more cells. Metabolism+heredity occur inside cells
2) cells are the smallest living things
3) cells arise only from division of previously existing cells.
Magnification
How many times bigger than life the object viewed appears
Combination of power of ocular+objective lens
Resolution
The ability to distinguish between 2 objects which are separate
Something that changes with each type of microscope used
Light microscope
Light passes through specimen+lenses
Lenses magnify and focus image
Light-condenser-slide-magnifier-ocular lens
Light shines from bottom
Resolution= approx. 0.2um or 200mm
Light microscope
Tissue prep
1) kill specimen
2) fix it (preserve with chemicals)
3) embed in wax or plastic
4) slice with microtome
5) stain it
Electron microscope
Electrons pass through or to specimen
Wavelength is shorter than light microscope - shorter wavelength increases resolution
Electron source on top of microscope
Uses magnets as lenses
Scanning electron microscope (SEM)
Specimen @bottom
Electrons go through 3 sets of magnetic lenses-through the coil-bounces off specimen-image read by detector-image goes through black box and to viewing screen.
Resolution= 10nm - creates 3D image
Transmission electron microscope (TEM)
Specimen goes after 1st electromagnetic lens-acts as condenser
Electrons pass to objective lens+to the projective lens
Viewing screen is @ bottom where image can be viewed
Resolution: 0.2nm - 1000x better than light microscope
Much larger than light and requires a vacuum
TEM
Tissue prep
1) kill specimen
2) dehydrate specimen
3) slice + put in plastic
4) stain with heavy metals
Prokaryotic cells
Before nucleus Small,simple,unicellular No membrane bound organelles Live anywhere eukaryotes live,but can live many place eukaryotes can't Most abundant Oldest No nucleus Nucleoid region (DNA)
Eukaryotic cells
After nucleus Larger than prokaryote Complex-specialized cells Some uni but most multicellular Have membrane bound organelles Has nucleus Complex DNA (in nucleus)
Prokaryotes
Bacteria
Structures
Ribosomes Plasmid Flagellum Cytoplasm/protoplasm No nucleus/nucleoid region instead Little structure Rod/spherically shaped Plasma membrane Pili Cell wall (peptidoglycan)
Bacteria
Gram staining (+/-)
Gram + bacteria: thick cell wall-crystal violet stain makes cell wall purple
Gram - bacteria: thin cell wall-crystal violet does not stain-use another stain which turns it pink
Cytoplasm/protoplasm
Semi fluid matrix
Fills interior of cell
Contains all sugars, amino acids, and proteins cell needs
Jello-like consistency
Pilus
Hair-like extensions
Allows cell to transfer genetic materials from one cell to another
Nucleoid region
The area near the centre of the cell that contains most of the genetic material DNA
In cells with no nucleus
Ribosomes
Circular shape
Organelles that carry out protein synthesis
Made of 2 subunits that are made of rRNA and proteins
On RER
Subunits only join to make proteins
Plasmid
A small fragment of circular double stranded DNA that replicates on its own.