Cellular and Lab Techniques Flashcards
(32 cards)
Cell cycle regulation
CDKs (always active) — Cyclins (activate CDKs) — Cyclin-CDK complexes (phosphorylate other ptoteins to coordinate cell cycle - p27 inhibits CDK in G1 to inhibit cycle) — Tumor suppressors (p53 and HYPOphoshporylated Rb inhibit G1 to S progression — CDK4 leads to HYPERphosphorylated Rb, releases E2F and enters S phase)
3 cell types
Permanent (remain in G0 - neurons, skeletal and cardiac muscle, RBCs) — Stable (Enter G1 from G0 when stimulated - hepatocytes, lymphocytes) — Labile (never go into G0, divide rapidly, most affected by chemo - bone marrow, gut epithelium, skin, hair follicles, germ cells)
Endoplasmic reticulum
Rough (secretory proteins, Nissl bodies in neurons make NTs, free ribosomes make cytosolic and organellar proteins - mucus cells of small intestine have a lot of RER) —- Smooth (steroid synthesis and detoxification - liver hepatocytes and steroid hormone producing cells of adrenal cortex have a lot of SER)
Golgi functions
Modifies N-oligosaccahrides on asparagine, adds O-oligosaccharides on serine and threonine, adds mannose-6-phosphate to proteins for trafficking to lysosomes
I cell disease
Defect in N-acetylglucosaminyl-1-phosphotransferase –> failure of golgi to phosphoryalte mannose residues –> proteins secreted extracellularly rather than to lysosomes —- coarse facial features, clouded corneas, restricted joint movement, high plasma levels of lysosomal enzymes
Trafficking proteins
SRP (ribosome to RER – mutation causes accumulation of proteins in cytosol) — COPI (Golgi to Golig, cis golgi to ER) — COPII (ER to cis Golgi) — Clathrin (trans Golig to lysosomes, plasma membrane to endosomes)
Peroxisome
Catabolism of very long chain fatty acids, branched chain fatty acids, and amino acids
Proteasome
Degrades damaged or ubiquitin tagged proteins
Cytoskeletal elements
Microfilaments (muscle contraction, cyokinesis - actin) — intermediate filaments (maintain cell structure - desmin, cytokeratin, lamins, neurofilaments) — microbutules (movement, cell division - cilia, flagella, mitotic spindle)
Stains for intermediate filaments
Vimentin (Connective tissue) – DesMin (Muscle) – Cytokeratin (Epithelial cells) – GFAP (NeuroGlia) — Neurofilaments (Neurons)
Microtubules
Heterodimers of a and B tubulin (each dimer has 2 GTP bound) — Dynein (retrograde to microtubule) and Kinesin (anterograde to microtubule) (KARD)
Drugs that act on microtubules
Microtubules Get Constructed Very Poorly - Mebendazole, Griseofulvin, Colchicine, Vincristine/Vinblastine, Paclitaxel
Cilia structure
9+2 arrangement — axonemal dynein links peripheral 9 doublets
Kartagener syndrome
Primary ciliary dyskinesia - dynein arm defect – infertility, increased risk of ectopic pregnancy, bronchiectasis, recurrent sinusitis, situs inversus
Na/K pump
Located in plasma membrane with ATP on cytosolic side – 3 Na go out of cell (phosphorylated) and 2 K come into cell (dephosphorylated)
Collagen
MC protein in body - stains with red safranin – Be (So Totally) Cool, Read Books (types of collagen)
Type I collagen
MC - Bone, Skin, Tendon (decreased in osteogenesis imperfecta type I)
Type II collagen
Cartilage (including hyaline), nucleous pulposus
Type III collagen
Reticulin (skin, blood vessels, uterus, fetal tissue, granulation tissue) – deficient in vascular type of Ehlers-Danlos syndrome
Type IV collagen
Basement membrane, basal lamina, lens – defective in Alport syndrome, targeted by antibodies in Goodpasture syndrome
Collagen synthesis
Inside fibroblasts: Syntesis (RER - translation of preprocollagen, glycine content!) –> Hydroxylation (RER - specific proline and lysine residues, requires vitamin C) –> Glycosylation (RER - forms procollagen with hydrogen and disulfide bones - problems forming helix in osteogenesis imperfecta) –> Exocytosis –> Outside fibroblasts: Proteolytic processing (cleaving disulfide terminal regions and making tropocollagen) –> Cross linking (reinforcement by covalent lysine-hydroxylysine linkage - problems in Ehlers Danlos)
Osteogenesis imperfecta
BRITTLE BONE DISEASE – MC form is autosomal dominant with decreased production of type I collagen – multiple fractures with minimal trauma, blue sclerae (choroidal veins), hearing loss (ossicles), dental imperfections (lack of dentin)
Ehlers-Danlos syndrome
Bad collagen synthesis – hyperextensible skin, tendency to bleed, and hypermobile joints (mutation in type V collagen) — can also have vascular type (very rare, type III collagen defect)
Menkes disease
X-linked recessive CT disease d/t impaired copper absorption and transport (defective Menkes protein) — decreased activity of lysyl oxidase – brittle, kinky hair, hypotonia, growth retardation