The Cell Flashcards
What is the H & E stain? What are its limitations?
Standard method of staining in histology; Hematoxylin = BLUE basic dye (positively charged), binds negatively charged DNA/RNA (and ribosomes, since they contain nucleic acid); Eosin = PINK acidic dye (negatively charged), binds positively charged “eosinophilic” mitochondria/cytoplasmic components; Limited ability to differentiate between cytoplasmic organelles and many other tissue components
What is the PAS method? What is chemistry behind it?
Periodic acid-Schiff method (PAS) = stain structures rich in polysaccharides (glycogen), mucopolysaccharides (ground substance, basement membrane, mucous), glycoproteins (thyroglobulin), & glycolipids; Chemistry = Periodic acid oxidizes glycols and alchols to aldehydes, which are stained REDDISH PURPLE by Schiff reagent
What is Osmium staining? What is its use in electron microscopy?
Blackens lipids and stains Golgi apparatus under light microscope; EM fixative
What is protoplasm? What are its two main divisions?
Contents of a cell; Divisions: (1) Karyoplasm - nucleus (2) Cytoplasm - protoplasm surrounding nucleus
Recall the 3 key size facts that must be remembered.
(1) Most eukaryotic cells = diameter of 7-20 microns (um), while prokaryotic cells are small (0.2-5 um), (2) Red blood cells = average diamter of 7.2 um = useful size reference, (3) Secretory granule = approx. diameter of 1 um
What are the main differences between naked eye, light microscope, and electron microscopes in terms of visibility?
Naked eye - large cells ~ 100 um; Light - 0.2 um resolution limit = cells and large constituents (nuclei, nucleoli, secretory granules, lysosomes, large mitochondria, and stained clumps of smaller structures); Electron - 1 nnm resolution limit = necessary to clearly see smaller organelles (membranes, ribosomes, macromolecular assemblies, & macromolecules).
Plasma Membrane - How is it visualized?
EM (since 10 nm thick); Cell limits can be seen by light microscope due to lots of glycoproteins and proteoglycans
Nucleus - What encloses the nucleopasm? What is the difference between heterochromatin and euchromatin?
Double bilary with nuclear pores; Chromatin: (1) Heterochromatin = condensed DNA and protein stainable with basic dyes, found in less transcriptionally active cells (2) Euchromatin = dispersed, not readily stainable DNA and protein, found in more transcriptionally active cells
Nucleoli - How are the stained, and why? Where are large nucleoli typically found?
Basic dyes due to high RNA content; Cells active in protein synthesis (note: nucleoli = site or ribosome synthesis)
Endoplasmic Reticulum (ER) - What are the two types of ER and their purposes? How does each stain with H & E? Desribe the SER found in liver and muscle.
(1) Rough ER: surround nucleus, attached ribosomes, first organelle into which membrane-bound or extracellular proteins are inserted (2) Smooth ER: lacks ribosomes, participates in lipid synthesis & detoxification; H & E staining - RER basophilic due to ribosomes w/ rRNA & SER stains poorly but more eosinophilic; SER in liver = contain lots of cytochrome P450, detox metabolic waste products, alcohol, and rugs; SER in muscle = sarcoplasmic reticulum, stores & releases calcium ions for muscle contraction
Golgi apparatus - What does the Gogli do? In what kinds of cells is it prominent? How is it stained?
Modified sugar side chains on proteins that are secreted or destined for plasma membrane or membrane-bound organelles; Prominent in cells synthesizing large amounts of glycoproteins or proteoglycans (e.g., globlet cells –> mucous in gut epithelium); Stained w/ osmium or silver stains, stains poorly with H & E - but may appear pale on one sid eof nucleus
Secretory vesicles and granules - What do they contain and do? What are some examples? To what side of the cell are granules secreted? How do they stain?
Specific substances synthesized by cells that are exported to extracellular medium; E.g., - zymogen granules, mucous droplets, & mast cell granules; Apical side; Pink/Eosinophilic/Acidophilic
Mitochondria - What two features characterize mitochondria?
(1) Double bilayer membranes (2) Cristae = folds projecting from inner membrane into matrix
Lyososome - How are they recognized? What activatives lysosomal enyzmes?
Membrane-bound organelles w/ granular material; Acidic pH
Give a very general overview of mitosis
Interphase = growth & synthesis (DNA replication) between divisions; 4 distinct phases of mitotic divisions = Prophase, Metaphase, Anaphase, & Telophase; Note: Karyokinesis (division of nucleus) preceds Cytokinesis (division of cytoplasm)
