This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Regarding proteoglycans, false is: \nSelect and explain. \nA. Chondroitin sulphate is a proteoglycan, B. They hold less amount of water, C. They are made up of sugar, D. They carry charge', 'role': 'user'}, {'content': 'Answer: B \nExplanation: GAGs are generally associated with a small amount of protein forming proteoglycans which contain >\xa0 95% carbohydrate. Whereas, glycoproteins contain primarily protein & a small amount of\xa0 carbohydrate.\nAll the GAGs, except hyaluronic acid, form proteoglycans. It is also the only GAG which is not sulfated\xa0 and also found in bacteria.\nProteoglycan monomer resembles a bottle brush as it consists of a core protein to which linear GAG\xa0 chains are covalently attached. Each chain may be composed of > 100 monosaccharide chains, remain\xa0 separated from each other because of charge repulsion.\nThe GAGs\xa0 present in the proteoglycans are polyanions and hence bind\xa0 polycations and cations such as Na+ and K+. This latter ability attracts water by osmotic pressure into the extracellularmatrix and contributes to its turgor. GAGs also gel at relatively low concentrations.\nBecause of the long extended nature of the polysaccharide chains of GAGs and their ability to gel, the proteoglycans can act as sieves, restricting the passage of large macromolecules into the ECM but allowing relatively free diffusion of small molecules.\xa0\nAgain, because of their extended structures and the huge macromolecular aggregates they often form, they occupy a large volume of the matrix relative to proteins.\n\n\xa0proteoglycan=GAGs + Protein (≤ 5%) = + proteins\nKey Concept:\nThe GAGs\xa0 present in the proteoglycans are polyanions and hence bind\xa0 polycations and cations such as Na+ and K+. This latter ability attracts water by osmotic pressure into the extracellularmatrix and contributes to its turgor. Thus, they hold more amount of water.', 'role': 'assistant'}]