60. How does ethanol cause proteins to precipitate from an aqueous solution? 61.
ID: 202313 • Letter: 6
Question
60. How does ethanol cause proteins to precipitate from an aqueous solution? 61. Suggest 2 ways that a cell can regulate microtubule assembly and disassembly? 62. What ensures that a chemotaxis process activates a response ata particular part of the cell membrane, ratherthan a cell-wide response? 63. What is the purpose of making an intracellular gradient of calcium when moving rather than making an uniform concentration after cells are induced? 64. What determines the length of a TMV particle? 65. Why is contact inhibition beneficial to multicellular eukaryotes? 66. Why is attachment dependent growth beneficial to multicellular eukaryotes?Explanation / Answer
ANS 60) ethanol precipitation is a method used to purify and/or listen rna, dna, and polysaccharides inclusive of pectin and xyloglucan from aqueous answers via including ethanol as an antisolvent.
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ANS 61) gtp hydrolysis has been shown to be a key regulator of microtubule polymerization dynamics. despite the fact that the precise mechanisms are poorly understood, two opposing fashions have been proposed to describe how gtp could modify the conformation of -tubulin/-tubulin from the intrinsically ‘bent spring’ form that resists straightening, to the straight conformation that gives upward thrust to microtubule balance. these models are called the allosteric model and the lattice version [1].the allosteric version, which is essentially supported through electron microscopy research suggests that gtp binding permits the tubulin dimer to undertake a polymerization-ready shape . the lattice model on the other hand suggests that conformational changes arise handiest after the dimer is integrated into the growing lattice.
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ANS 62) Chemotaxis is the motion of an organism in reaction to a chemical stimulus.somatic cells, bacteria, and other single-cellular or multicellular organisms direct their actions according to sure chemical compounds of their surroundings. that is crucial for bacteria to discover meals (e.g., glucose) by using swimming in the direction of the very best concentration of meals molecules, or to flee from poisons (e.g., phenol). in multicellular organisms, chemotaxis is essential to early development (e.g., motion of sperm toward the egg for the duration of fertilization) and next stages of improvement (e.g., migration of neurons or lymphocytes) in addition to in normal function and health (e.g., migration of leukocytes at some stage in harm or infection).similarly, it has been recognized that mechanisms that permit chemotaxis in animals may be subverted for the duration of most cancers metastasis.high quality chemotaxis happens if the movement is in the direction of a better concentration of the chemical in query; negative chemotaxis if the movement is in the opposite direction. chemically precipitated kinesis (randomly directed or nondirectional) may be known as chemokinesis
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ANS 63) Intracellular calcium concentrations in each cardiac and vascular easy muscle cells range from 10-7 to ten-5 m. extracellular concentration of calcium is set 2 × 10-three m (2 mm). consequently, there is a chemical gradient for calcium to diffuse into the cell. because cells have a bad resting membrane potential (approximately -90 mv in a cardiac myocyte), there is also an electrical force driving calcium into the cellular. but, except in the course of motion potentials whilst the cellular membrane permeability to calcium increases, there may be little leakage of calcium into the cellular. the calcium that enters the mobile throughout movement potentials (e.g., in the course of depolarization of pacemaker and non-pacemaker cardiac cells) have to be eliminated from the cell in any other case an accumulation of calcium might result in cell disorder.
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ANS 64) The range of nucleotides setermine the duration of tmv particle as period of tmv is 300 nm, at the same time as width is 18 nm. there's a gift of core of four nm in the tmv. inside the core helically coiled rna molecule is present, that's made of nearly 6500 nucleotides rna is enclosed within the protein coat, a capsid. the capsid is fabricated from 2130 capsomeres of a few length every capsomere is made up of 158 amino acids
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ANS 65) Contact inhibition refers to 2 exclusive however closely related phenomena: contact inhibition of locomotion (cil) and phone inhibition of proliferation (cip). cil refers back to the avoidance behavior exhibited through fibroblast-like cells whilst in touch with one another. In maximum cases, whilst two cells touch each different, they try and alter their locomotion in a exceptional route to avoid destiny collision. while collision is unavoidable, a extraordinary phenomenon occurs wherein increase of the cells of the subculture itself subsequently stops in a cellular-density established way.both sorts of contact inhibition are well-known residences of normal cells and make a contribution to the regulation of proper tissue boom, differentiation, and improvement. it's miles worth noting that each kinds of law are normally negated and conquer throughout organogenesis at some stage in embryonic development and tissue and wound recovery. but, touch inhibition of locomotion and proliferation are each aberrantly absent in most cancers cells, and the absence of this regulation contributes to tumorigenesis/
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ANS 66) Contact-inhibited cells go through cell cycle arrest, however do no longer senesce. in reality, it has been proven that contact-inhibited cells resume normal proliferation and mitogen signaling upon being replated in a much less confluent lifestyle. for this reason, contact inhibition of proliferation may be regarded as a reversible form of cell cycle arrest. furthermore, to transition from mobile cycle arrest to senescence, touch-inhibited cells should spark off increase-activating pathways consisting of mtor. once cells in high-density cultures come to be confluent enough such that the cellular place falls beneath a crucial cost,the adhesion formations cause pathways that downregulate mitogen signaling and cellular proliferation.the boom-promoting mtor pathway is therefore inhibited, and consequently the contact-inhibited cells can not transition from cell cycle arrest to senescence. this has critical implications in most cancers remedy; despite the fact that most cancers cells are not touch-inhibited, confluent cancer mobile cultures still suppress their senescence equipment. therefore, this can be a conceivable reason why senescence-inducing most cancers therapy pills are useless.
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