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28 Cards in this Set
- Front
- Back
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How are globular and fibrous proteins held together?
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Globular proteins are held together by hydrophobic interations and disulfide bridges--fibrous proteins are held together by covalent bonds like SCHIFF BASE BONDING
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Why is quaternary structure advantageous?
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Large proteins means the surface to volume ratio decreases, and more inner stuff is able to be hidden from the environment--also, it is really hard for mutated subunits to incorporate
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In addition to SA/V ratio and mutation exclusion, what are some additional advantages to quaternary folding?
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Subunits will be more likely to be built correctly--more intricate catalytic sites can be achieved--multiple enzymatic activities can occur--Cooperativity
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Describe alcohol dehydrogenase.
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Two identical subunits joined by beta sheets that run antiparallel to each other--zinc atom oxidizes ethyl alcohol to stimulates collagen synthesis(cirrhosis)
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Pre-albumin is actually what? Describe its structure. What can it do in the body?
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Transthyretin: a protein that carries thyroid hormone throughout the body--two beta pleated sheets running antiparallel to each other--it can precipitate out in the body(amyloidosis) and cause problems
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Antibody heavy and light chains are joined by what?
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Disulfide bonds
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What is special about what happens to pyruvate when it is made?
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It is processed by pyruvate dehydrogenase: an enzyme superstructure that contains 4 enzymes and 5 cofactors
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Describe the tobacco mosaic virus.
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over two thousand subunits around the viral RNA
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Describe collagen superstructure.
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Cylinder composed of 5 different triple alpha helices(4.4D long) staggered at a distance of 68 nm from each other(D)
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What promotes hydrophobic interactions?
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Warming
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Describe myosin structure.
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Myosin heads are staggered 14 nm apart
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How does fibrin work?
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Fibrinopeptides are cleaved off the fibrin protein, which can then polymerize quickly with itself and cause clotting
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What is Hb protein designed to carry?
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CO2, O2, and H+
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What is the difference between myoglobin and hemoglobin?
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Myoglobin has a very polar surface, and so needs only one subunit--Hb has four subunits which have nonpolar sections that cannot change independently of each other
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How does oxygen bind in Hb? What does this protect against?
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It binds to the iron ion in the center of the heme--Iron ions prefer to interact with SIX ligands, so oxygen provides the sixth--it bonds at an angle caused by histidine, such that it can more easily be removed later--this protects against binding by CO and suffocation
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Which has a greater O2 affinity--Hb or myoglobin?
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Myoglobin
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What happens to certain bonds when oxygenation of Hb occurs?
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Salt bridges are broken and R form is achieved
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What does 2,3 BisP do?
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Promotes deoxy state of Hb--it encourages oxygen unloading at the tissue level by placing a negative charge into the center of the Hb and by cross-linking/stabilizing the deoxygenated state of Hb
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How does fetal Hb differ from adult Hb?
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It has gamma chains instead of beta, and it doesn't take up 2,3 BisP as easily, and so its affinity for oxygen is higher than adult Hb--this allows it to TAKE O2 from the mother
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Describe how pH, O2 presence, and CO2 presence influence oxygen binding in Hb
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Low O2, low pH, and high CO2 induces the T(tense) state in Hband reduces its affinity for O2--vice versa to R state in the lungs
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RBC's are lysing everywhere! What is wrong?
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Hemolytic anemia--mutation causing too many charged amino acids in the binding site, forcing out the iron, which travels to the membrane and rips it
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What are thalassemias?
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Alpha or beta subunits are not formed properly and so anemia occurs--I think beta is terminal
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Discuss the energy associated with protein folding
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It is barely a favorable reaction(negative delta G)
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How is fibrous folding different from globular folding?
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Fibrous folding is ENTHALPY driven, which means that it is driven by H-bonding
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What amino acid allows for elastin's movement?
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Valine--DUH
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How does elastin maintain its superstructure?
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Through lysine desmosine cross linkage
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What happens to the saturation curve for Hb as the pH decreases?
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It is shifted to the right, because deoxyhemoglobin has a greater affinity for H+ ions than does oxyhemoglobin, so it is advantageous to attain that state
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What is the Bohr Effect?
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The shifting of Hb's oxygenation curve to the right as the CO2 or H+ levels go up
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