Histology: eukaryotic cells, intercellular junctions & staining Flashcards
define an organelle
essential to life + membrane bound
define an inclusion and give an example
non-essential + not membrane bound, e.g. lipid droplet
describe the membrane of a eukaryotic cell
selectively permeable amphipathic phospholipid bilayer with integral/peripheral/transmembrane proteins and imbedded cholesterol
where is euchromatin and heterochromatin formed and describe the difference between them
both found in nucleus
euchromatin = dispersed & actively transcribed
heterochromatin = condensed & not actively transcribed
what are the 4 main types of intercellular junction
gap, anchoring, junctional complexes and occluding junctions
what is the role of occluding/ tight junctions and what are they also known as
prevent diffusion
also called zonula occludens
what are the 2 different types of anchoring junction
zonula adherens and macula adherens
what is the role of zonula adherens
link submembrane actin bundles via link molecules, which attach to transmembrane cadherin in extracellular space(anchoring junctions)
what is the role of macula adherens
desmosomes, they link submembrane intermediate filaments of adjacent cells
what is the role of communicating/gap junctions and where are they often found
selective diffusion and transfer of molecules between cells
common in smooth/cardiac muscle
describe the structure of communicating/gap junctions
circular patch, studded with pores made by ‘connexon’ proteins
what colour does hematoxylin stain
purple/blue
what colour does eosin stain
pink/red
does eosin or hematoxylin stain acids or bases
eosin = bases hematoxylin = acids
which part of the cell does eosin stain
cytoplasmic proteins(cytoplasm)
