Week 1 Flashcards
Define resolution
Ability to distinguish between two objects; dependent on wavelength of energy source (not strength)
Fixative for:
A) light microscope (LM)
B) electron microscope (EM)
A) formalin (formaldehyde & water)
B) osmium tetroxide or gluteraldehyde
Steps of tissue preparation
- Fixation
- Dehydration
- Embedding
- Sectioning
- Staining
Objective of fixation:
- End cellular processes
- Preserve protein components
- Micro organisms destroyed
- Tissue hardening
Hematoxylin & Eosin dye
Hematoxylin: blue/purple, basic dye; net positive charge; binds an anionic (net negative charge)
Eosin: pink/red, acidic dye; net negative charge; binds cationic (net positive charge)
What stain is used on carbohydrates?
PAS (periodic acid -Schiff)
What stain is used for reticular fibers?
Silver impregnating
Two types of EM
TEM: transmission electron microscopy: beam passes through material
SEM: scanning electron microscopy: beam reflects off metal-coated sample
What are artifacts?
Abnormalities of slides due to human error
Define epithelium:
Continuous layer of cells that sit on a basement membrane
When enzymatically transferred to outer leaflet, signals programmed cell death
Phosphatidylserine
What is a lipid raft?
Specialized cholesterol enriched micro domains; functions to signal transduction and endocytosis
What Ian glycocalyx?
Carbohydrate rich zone covering the cell’s surface’ made up of glycolipids, glycoproteins, and proteoglycans. Established micro environment, protection, cell recognition, and cell to cell interactions
What is a Lectin?
Used for cell to cell integration; binds to carbohydrates and causes agglutination
Permeable vs highly impermeable molecules
Permeable: hydrophobic, non-polar, uncharged, gases (O2, CO2)
Highly impermeable: charged (ions: H+, Na+, K+), polar, charged
What is the function of channel and transporters?
To increase the permeability of the membrane to molecules
3 types of endocytosis
- Receptor-mediated: specific; clathrin dependent
- Pinocytosis: non-specific;
- Phagocytosis: actin dependent; very specific (Ab)
Purpose of adaptin and dynamin in receptor-mediated endocytosis
Adaptin: interacts with clathrin and cargo receptors that then leads to basket-like cage formation
Dynamin: mediate vesicles pinching off from the plasma membrane; requires GTPase
What is required for accurate vesicle targeting?
V-SNARE & t-SNARE
What is an endosome?
Membrane enclosed structure that is associated with the endocytotic pathway.
Early endosome: sort and recycle proteins
Late endosome: receives proteins for degradation and newly synthesized lysosomal enzymes -> matures into lysosomes
The indigestible substances remaining after phagosome and lysosomes digest particles
Residual body
