Microscopy, Golgi, Erthyrocytes Flashcards
how does basic light microscope work?
resolution power?
light passes through object and through eyepice + objective lens which manifies the object.
0.2 um
How does fluorescence microscopy work
a cellular substance when irradiated by a light of proper wavelength emits light with LONGER wavelength-fluorescence.
Cell irradiated with UV and emits visible light
Requires cells to be stained with fluorescent dye.
How does phase contrast microscopy work?
measures time taken for light to pass through object and visualises it accordingly
Based on principle that light changes its speed when passing through cellular and
extracellular structures with different refractive indices.
cells do not have to be stained, they can be colourless. Can view living cells and no need for fixation.
What is Confocal microscopy?
reduces excess light exposure to specimen that could reduce resolution of image (like in bright field)
sharp focus due to laser and plate with pinhole aperture
images produced on computer
What is polarizing light microscopy?
Polarized light used meaning light only vibrates in one direction
The ability to rotate the direction
of vibration of polarized light is called birefringence
macromolecules located between light and lens are visible, everything else black
How does an transmission electron microscope work
Magnification and resolution
beams of electrons passes through specimen from metallic filament cathode that moves towards anode.
image shows white, grey or black depending on how readily electeons passed through
res: 3nm mag: up to x120,000
How can you improve the contrast and resolution of TEM
Using heavy metal ions to the fixative/dehydrating solutions
Name 2 techniques that allow TEM to study cells without fixation and embedding
cryofracture
freeze etching
both freeze objects using nitrogen and causes membrane to split
How does scanning electron microscope work?
Electrons do not pass through object pnly scans surface.
specimen dried and spray coated with thin layer of metal (gold) that reflects electrons and captured by detector producing black and white image
3D
Who discovered the Golgi apparatus
Camillo Golgi 1898
Structure of Golgi
flattened sacs- cisternae
lumen
Cis face (entry) : takes proteins from RER
trans face (exit) pushes proteins out for other use in cell
Contains lots of enzymes
Function of golgi
- modifying proteins
- packages enzymes
- sorts materials for lysosomes
what is COP I + COP II
COP II helps in forward movement of vesicles
COP I helps in backwards movement
aids vesicular traffic
Types of epithelial tissue and their function.
- cuboidal - secretion
- simple columnar - absorption/secretion
- simple squamous - mesothelium
- pseudostratified ciliated columnar - part of respiratory tract
- Stratified squamous keratinized - skin
- stratified squamous non keratinized - oral cavity, vagina, oesophagous
Diff epithelial junctions
- Adhering - protein layer attaching to cells microfilaments
- Tight/occluding - pair of transmembrane proteins, controls passage of ions
- desmosomes - Attaches to microfilaments of cytoskeleton made of keratin protein (cadherins)
- Hemidesmosomes - attaches epithelial to basement membrane. integrin proteins.
- Gap - made of connexins that attaches cytoplasm of cells. allows small ions to transfer from one cell to another.
