Term
what hemoglobin does for the body |
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Definition
carries oxygen to tissues and contributes to the transport of CO2 and H ions back to the lungs |
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Term
is allostery limited to enzymes? |
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Definition
no; hemoglobin is an allosteric protein |
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Term
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Definition
found in muscle, this protein facilitates the diffusion of O to cellular sites and provides reserve supply of O |
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Term
the kinetics of hemoglobin |
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Definition
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Term
the kinetics of myoglobin |
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Definition
hyperbolic curve (like that of a Michaelis-Menten enzyme) |
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Term
what determines the amount of O hemoglobin releases as it passes thru the tissues? |
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Definition
allosteric regulators at the tissues |
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Term
why does hemoglobin release more O than myoglobin would? |
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Definition
because of cooperativity between O binding sites in hemoglobin |
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Term
the 2 forms myoglobin can exist in |
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Definition
-deoxymyoglobin -oxymyoglobin |
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Term
where O binds in hemoglobin and myoglobin |
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Definition
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Term
depiction of a heme group |
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Definition
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Term
oxidation state of hemoglobin's Fe in normal conditions |
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Definition
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Term
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Definition
the histidine residue that occupies the 5th coordination site of the Fe atom in hemoglobin; it's on one side of the plane of the heme group |
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Term
the part of the Fe atom in hemoglobin available for binding with O |
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Definition
the 6th coordination site; this is on the opposite side of the proximal histidine |
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Term
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Definition
resides on the opposite side of the heme group from the proximal histidine |
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Term
what the distal histidine does for hemoglobin |
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Definition
-prevents oxidation of the heme to the ferric (Fe+3) ion
-reduces the ability of CO to bind to the heme
-H bonds with bound O to stabilize it |
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Term
depiction of deoxyhemoglobin and oxyhemoglobin |
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Definition
[image]
in deoxy form, the Fe is slightly outside the plane, but in the oxy form, the Fe is in the plane |
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Term
how O bound to hemoglobin is stabilized |
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Definition
by forming a H bond wit the distal histidine |
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Term
the structure of hemoglobin |
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Definition
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Term
the subunits of hemoglobin |
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Definition
-2 α subunits
-2 β subunits
functions as a pair of identical αβ dimers, together forming a tetramer
α1β1 dimer and α2β2 dimer |
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Term
the αβ dimers of hemoglobin are linked by... |
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Definition
an extensive interface which includes, among other regions, the carboxyl terminus of each chain |
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Term
the interface between the αβ dimers of hemoglobin consists of... |
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Definition
among other regions, the carboxyl terminus of each chain |
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Term
the allosteric state deoxyhemoglobin corresponds to |
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Definition
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Term
the allosteric state oxyhemoglobin corresponds to |
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Definition
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Term
how O binding to hemoglobin affects the quaternary state of hemoglobin |
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Definition
binding of O on one subunit makes the α1β1 and α2β2 dimers rotate about 15 degrees with respect to each other
converts from T to R state |
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Term
the molecule that regulates hemoglobin within red blood cells |
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Definition
2,3-biphosphoglycerate (2,3-BPG)
regulates hemoglobin's affinity for O such that sufficient amounts are supplied to aerobic tissues |
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Term
how 2,3-biphosphoglycerate (2,3-BPG) regulates hemoglobin's O affinity |
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Definition
goes in the center of the deoxyhemoglobin (T state) and binds to 3 positively charged groups on each β chain by way of ionic bonds, stabilizing the T state and reducing its affinity for O |
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Term
what must happen to 2,3-biphosphoglycerate (2,3-BPG) for hemoglobin to change from the T to the R state? |
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Definition
the bonds between hemoglobin and 2,3-biphosphoglycerate (2,3-BPG) must break ad the 2,3-biphosphoglycerate (2,3-BPG) must be expelled from the molecule |
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Term
depiction of 2,3-biphosphoglycerate (2,3-BPG) in deoxyhemoglobin (T state) |
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Definition
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Term
the β chain groups 2,3-biphosphoglycerate (2,3-BPG) ionically bonds with |
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Definition
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Term
depiction of 2,3-biphosphoglycerate (2,3-BPG) and the β chain groups it ionically bonds with |
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Definition
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Term
is 2,3-BPG the only allosteric regulator of hemoglobin? |
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Definition
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Term
how tissues most in need of O, such as muscle, get the O they need |
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Definition
1: muscle releases CO2
2: CO2 diffuses into the red blood cell
3: this rxn occurs in the red blood cell: CO2 + H2O <--> H2CO3 <--> HCO3- + H+
this enhances the release of O fromn hemoglobin |
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Term
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Definition
the regulation of O binding by H+ and CO2 |
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Term
other than regulatory molecules, what can affect hemoglobin's affinity for O? |
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Definition
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Term
effect of pH on hemoglobin's affinity for O |
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Definition
lower pH leads to lower affinity for O |
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Term
effect of partial pressure on hemoglobin's affinity for O |
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Definition
lower partial pressure leads to lower affinity for O |
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Term
the chemical basis of pH regulating hemoglobin's affinity for O (Bohr effect) |
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Definition
at low pH, the side chain of histidine gets protonated to form a salt bridge with the CO2- group on the aspartate, stabilizing the T state, favorin greater release of O at actively metabolizing tissues
at high pH, histidine's side chain is not protonated and the salt bridge does not form, favoring O binding |
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Term
how CO2 reduces hemoglobin's affinity for O |
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Definition
CO2 binds with the terminal amino groups to form negatively charged carbamate groups, stabilizing the T state, favoring the release of O |
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Term
where the amino termini are in hemoglobin |
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Definition
at the interface between the αβ dimers |
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