Subcellular organelles and the cytoskeleton Flashcards
describe the plasma membrane
-lipid bilayer with extrinsic and intrinsic proteins
-forms continuous barrier that regulates movement of molecules and ions in and out of the cell
-many membrane proteins and lipids are bound to carbohydrates to form glycoproteins and glycolipids
-membrane is fluid bc proteins and lipids can move
what is a lysosome?
membrane-enclosed organelle that contains many degradative enzymes
what are example of enzymes in a lysosome?
-nucleases
-phosphatases
-glycosidases
-proteases
what are the functions of lysosomes?
-eliminate unwanted cellular materials and recycle their components
-destroy yeast and bacteria
what are endosomes?
membrane-bound vesicles formed via endocytosis
what is receptor-mediated endocytosis?
specific type of endocytosis where ligands bind to receptors on cell surface and endocytosis is triggered
where are the receptors in RME situated?
in coated pits on the cell membrane - surface is coated in clathrin
what happens in RME?
-when molecules attach to receptors, they are both taken into the cell in a clathrin coated vesicle (early endosome)
-as endosome grows, other vesicles from gb join and provide enzymes
-the endosome is now a lysosome
why is clathrin useful for an endosome?
-helps get its rounded shape
-helps it to bud off from membrane
what does RME help cells to take up?
large amounts of molecules that are present in low concentrations in the extracellular fluid
what happens to clathrin in RME?
recycled to cell surface in recycling endosomes
why might RME be a bad thing?
because virus and bacteria can also gain access to the cells
what is a peroxisome?
small organelle which contains the enzyme catalase and some oxidases and it is similar in size to lysosome
what do peroxisomes do?
-degrades fatty acids
-convert cholesterol to bile
-synthesise plasmalogens which is a component of myelin
what is produced in the reactions bw peroxisomes and bile/fatty acids?
-hydrogen peroxide
-this is degraded by a catalase
how are peroxisomal disorders caused?
-mutations in peroxisomal enzymes or faults in peroxisomal assembly
-toxic long chain fatty acids accumulate bc they are not being degraded
-causes deficiency of plasmalogens
what is autophagy?
the degradation of worn, abnormal or malfunctioning cellular components
what is microautophagy?
autophagosome fuses with lysosome
what is macroautophagy?
direct engulfment of material into lysosome
what is an autophagosome?
spherical structure with double membrane
what is the keystone pathogen hypothesis?
certain low abundance pathogens can bring about inflammatory disease by remodelling a benign microbiota into a dysbiotic one
what is the keystone pathogen hypothesis?
certain low abundance pathogens can bring about inflammatory disease by remodelling a benign microbiota into a dysbiotic one
What is P. gingivalis and what does it do?
-pathogenic black pigmented anaerobic bacterium
-secretes gingipains which cause damage
-invades oral epithelium by hiding in autophagosome
what is exocytosis?
process of moving materials from within a cell to the exterior of the cell - is a type of active transport bc requires energy