Biochemistry: Cellular Quick Hits
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58 terms
Terms | Definitions |
|---|---|
 What are the stages of mitosis? | prophase - metaphase - anaphase -telophase |
| What enzyme has to be activated for the cell cycle to progress? | Cyclin-CDK complexes: Cyclin-dependent kinases are consitutive and inactive, cyclins are regulatory proteins that are phase specific and bind CDKs |
| G1 to S progression is moderated by what tumor suppresor genes? | p53 and RB |
| During what phase does microsatellite instability occur? | S phase |
| During what phase does mismatch repair occur? | G2 |
| During what phase does proofreading occur? | S |
| What cells remain in G0? | neurons, skeletal and cardiac muscle, RBCs |
| What cells are considered "stable" and enter G1 from G0 when stimulated? | Hepatocytes, leukocytes, make them when you need them |
| What cells never enter G0? | Bone marrow, gut epithelium, skin, hair follicles, all divide rapidly and have a short G1 |
| What two types of cells are especially rich in RER? Why? | Mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells:: it's the site of secretory (exported) proteins |
| What hydrophobic addition to proteins occurs in the RER? | N-linked oligosaccharide |
| Nissl bodies synthesize what? | RER of neurons: make enzymes like choline acetyltransferase (responsible for Ach production) and peptide neurotransmitters |
| What modification is required for peptides destined to be transmembrane receptors? | C-terminal palmitoylation is required for membrane anchoring (RER) |
| What modification is required for peptides destined for lysosomes? | Mannose-6-P, added in the cis-golgi apparatus |
| What is produced in the smooth endoplasmic reticulum? | steroid synthesis and detoxification of drugs and poisons, synthesis of triglycerides |
| The golgi apparatus modifies what on asparagine? | Modifies N-oligosaccharides |
| The golgi apparatus adds what to serine and threonine? | O-oligosccharides |
| Coarse facial features, clouded cornea, restricted joint movement, high plasma levels of lysosomal enzymes. Kid dies in childhood. Enzyme deficiency? | GlcNAc phosphotransferase deficiency: you cannot phosphorylate mannose to make mannose 6-P and therefore cannot mark substances for lysosome storage. Enzymes are subsequently secreted outside the cell rather than being sent to the lysosome |
| Proteins coated with COPII are destined for where? | anterograde travel from the RER to the cis-Golgi |
| Proteins coated with COPI are destined for where? | retrograde travel from the golgi to the RER |
| Clathrin pits take proteins where? | trans-golgi --> lysosomes and the plasma membrane --> endosomes via receptor mediated endocytosis |
| What is a peroxisome? | membrane-enclosed organelle involved in the catabolism of very long fatty acids and amino acids |
| What is a proteosome? | Barrel-shaped protein complex that degrades the world (if it's marked with ubiquitin |
| Describe the structure of a microtubule. | Cylindrical structure make of a helical array of alpha and beta tubulin. Each dimer has 2 GTP bound. These grow slowly and collapse quickly |
| Where do you find microtubules? | flagella, cilia, mitotic spindles |
| What structures are involved with slow axoplasmic transport in neurons? | microtubules |
| Dynein transports in which direction? | Retrograde (Dine in) |
| Kinesin transports in which direction? | Anterograde |
| Brochiectasis and recurrent sinusitis, the PMI is on the right side. Can this man have babies? | Unlikely, Kartagener's syndrome is associated with infertility since the sperm have a modified cilia for a flagellum and will be immotile |
| What is axonemal dyenin? | ATPase that links peripheral 9 doublets and causes bending cilium by differential sliding of doublets |
| Where do you find actin and myosin? | microvilli, muscle contraction, cytokinesis, adherens junctions |
| Where do you find microtubules? | cilia, flagella, mitotic spindle, axonal trafficking, centrioles |
| Where do you find intermediate filaments? | Vimentin (CT), desmin (muscle), cytokeratin (epithelium), lamins, glial gibrillary acid proteins, neurofilaments |
| What is desmoplakin? | Interacts with intermediate filaments, it's a intracellular portion of hemidesmosomes |
| Recurrent pyogenic infections and partial albinism with peripheral neuropathy. What is the pathogenesis? | Chediak-Higashi: AR defect in lysosomal regulator trafficking gene. Results in microtubule dysfunction in phagosome-lysosome fucsion leaving the patient suscpetible to staphylococci and streptococci. Smears will show inclusions of nucleated blood cells |
| Describe the composition of the plasma membrane. | cholesterol, phospholipid, sphingolipids, glycolipids and proteins. An increased cholesterol or LCFA content will decrease fluidity and increase melting temperature |
| Where do you find Connexin? | Gap-Junctions |
| Where do you find E-Cadherin? | Zona adherens >zona occludens > desmosomes... this is an epithelial cell anchoring protein |
| How do you stain for connective tissue? | Vimentin |
| How do you stain for muscle? | Desmin |
| How do you stain for Cytokeratin? | Epithelial cells |
| How do you stain for neuroglia? | GFAP |
| How do you stains for neurons? | Neurofilaments |
| How does Ouabain inhibit the sodium potassium pump? | Antagonist of K+ binding site |
| What structures are predominately type I collagen? | Bone, Skin, Tendon, dentin, fascia, cornea, late wound repair |
| What structures are predominately type II collagen? | Cartilage (including hyaline), vitreous body, nucleus pulposus |
| What structures are predominately type III collagen? | Reticulin, e.g. skin, blood vessels, uterus, fetal tissue, granulation tissue |
| What structures are predominately type IV collagen? | Basement membrane, basal lamina, lens of eye |
| Tram-tracking of glomerular basement membrane and hearing loss. What type of collagen is defective? | Type IV |
| What type of collagen compromises the epiphyseal plate? | Type X |
| Describe, in detail the synthesis of collagen. | 1) synthesis begins in the RER with translation of alpha chains (preprocollagen) which usually consists of Gly-X-Y (where X and Y are proline, hydroxyproline, or hydroxylysine) 2) in the ER, proline and lysine residues are hydroxylated by either prolyl hydroxylase or lysyl oxidase... these enzymes are vitamin C dependent 3) In the ER, pro-alpha-chain hydroxylysine residues are glycosylated and becomes procollagen via hydrogen and disulfide bonds... this is our triple helix 4)Procollagen is exocytosed into the EXTRACELLULAR SPACE 5)Outside the fibroblast, terminal regions of procollagen are cleaved to form insoluble tropocollagen by procollagen peptidase 6)Lysyl oxidase (requires oxygen and copper) cross-links staggered tropocollagen molecules between lysine and hydrolylysine to make collagen fibrils |
| Child with multiple fractures, blue sclera, hearing loss, and dental imperfections. Explain these findings. | Osteogenesis imperfecta: AD type I collagen Blue sclera are from the translucency of connective tissue over the choroid Hearing loss due to abnormal middle ear bones Dental imperfections from lack of dentin |
| What type of collagen is defective in Ehlers-Danlos? | Type III (reticulin) found in skin, blood vessels, uterus, fetal tissue, and granulation tissue |
| Child with hyperestensible skin, a tendency to bleed, and hypermotile joints. What enzyme and subsequent step of collagen synthesis is mutated? | Procollagen Peptidase located extracellularly, lack of this prevents the cleavage of terminal regions of procollagen. Failure to produce insoluble tropocollagen |
| Proline and glycine are components of what protein fouind in lungs, large arteries, elastic ligaments, vocal cords, ligamenta flava (connect vertebrae)? | Elastin |
| Wrinkles of aging are due to decreased production of what? | Elastin and collagen |
| Tall patient with long extremities, pectus excavatum, hyperextensible joints, long tapering fingers. What complications is this person susceptible to? | Marfan's syndrome, fibrillin defect: cystic medial necrosis of the aorta --> aortic incompetence and dissecting aortic aneurysms, floppy mitral valve, subluxation of the lenses (fibrillin is extracellular component) |
| What enzyme is responsible for breaking down elastin? | elastase, which is normally inhibited by alpha1-antitrypsin |
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