Cell biology midterm #1
Microscopy in the 1600-1800s (1665)
Hooke devised compound microscope and illumination system
Diverse organisms explored, and first account of internal mushroom structure
coined term "cell"
Microscopy in the 1600-1800s (1674)
van leewenhoek
First Protoza (bigger) and Bacteria viewed under microscope
Discovered animal and plant cells were usually 5-20 micrometers
Microscopy in the 1600-1800s (1881)
Cajal
Used silver nitrate stain to prove that each nerve cell is independent, and nerve synapses transfer nerve impulses from one cell to another
Microscopy in the 1900s (1952)
Electron microscopy: being able to observe smaller cells
Provides evidence of cytoskeleton; the ER is studded with ribosomes, lipid bilayer, and contracting muscle
Microscopy in the 1900s (1960s)
x-ray crystallography and confocal microscopy (3D structures of crystallized molecules, higher res)
Microscopy in the 1970s-1990s
Fluorescence: stains, antibodies, tagged proteins for visualizing things in living cells
Light microscopy requirements
1. Focus light through condenser
2. Specimen prepared properly (fixed/not fixed)
3. Lenses (objective, tube, eyepiece)
0.2µm resolution, can see general structures within a cell, and can be used on fixed (cut) samples or stained samples
Fluorescent microscopy + requirements
Similar to light microscopy but
1. Diff wavelengths filtered to the specimen
2. 2nd filter blocks other light - only light emitted from the sample is passed to the eyepiece
Confocal fluorescent microscope: generate optical section of a sample to generate 3D images (specimen scanned with laser beam)
Electron microscopy
Highest magnification and best resolution
Transmission electron microscope: beams of electrons rather than light to yield better resolution
Scanning electron microscope: uses electrons to image small surface structures.
Cannot be used on living samples (only fixed samples)
Cell membrane structure
Structure: Has a phospholipid bilayer, which is a thin (5nm) membrane composed of 2 lipid sheets to prevent molecules from either side to freely mix with each other.
Cell membrane function
Selectively permeable, allows for import and export of material, and is flexible for growth and movement of the cell
Membrane lipid structure
1 Hydrophilic head, 2 hydrophobic tails; has an ampipathic structure. Has a molecule of glycerol
Forms a bilayer in water
Ampipathic
Has hydrophobic and hydrophilic components in one molecule