Biochem Exam 3- Blood

Front 1

blood contains... (10)

Back 1

water
cells
proteins
sugars
lipids
hormones
vitamins
electrolytes
dissolved gases
cellular wastes

Front 2

proportions of water in blood

Back 2

90% (intra and extracellular)

Front 3

proportion of cells in blood volume and what types

Back 3

40%
RBC,WBC,platelets

Front 4

proportion of RBC out of all blood cells

Back 4

99%

Front 5

what is the most abundant extracellular and intracellular proteins in blood

Back 5

albumin
also hemoglobin- most abundant intracellular

Front 6

reference range for hematocrit and what is it

Back 6

40%
ratio of cell volume/total volume

Front 7

what is serum and how do you collect it?

Back 7

if you collect blood in untreated tube, it will clot. then you centrifuge, so all the clot proteins and cells (insoluble) go to the bottom. you are left with serum (pure liquid part of blood)

Front 8

what is plasma and how do you collect it?

Back 8

plasma is serum + soluble clot proteins. it is collected by collecting blood in treated tubes (no clotting). When centrifuged, the soluble clot proteins are still in the liquid phase.

Front 9

citrate and EDTA

Back 9

calcium chelators (bind Ca++ needed for clotting) used in treated tubes to prevent...clotting of blood

Front 10

low hematocrit

Back 10

anemia

Front 11

high hematocrit

Back 11

dehydration (extracellular volume is lower)

Front 12

albumin roles (3)

Back 12

helps maintain water balance between blood and tissue
transport of ions, especially calcium
transport of organic molecules like fatty acids (not water soluble, need to complex with albumin to be more water soluble)

Front 13

alpha-1 globulin example

Back 13

alpha-1-antitrypsin

Front 14

alpha-2-globulin example

Back 14

ceruloplasmin- involved in copper transport

Front 15

beta-globulin example

Back 15

transferrin- delivers iron to cells

Front 16

gamma-globulin example

Back 16

Ig (IgG most abundant serum antibody)

Front 17

order of negative charge of serum proteins (most negative --> positive)

Back 17

albumin, a1, a2, beta, gamma

Front 18

hemestasis definition

Back 18

prevention of blood loss due to bleeding

Front 19

events that occur during hemestasis

Back 19

1) formation/aggregation of fibrin at damage site
2) clumping of platelets at dmg site
3) local vasoconstriction
4) repair of damage (slow process)

Front 20

fibrinogen

Back 20

precursor of fibrin that cannot aggregate due to excessive negative charges (electrostatic repulsion)

Front 21

how is fibrinogen turned into fibrin?

Back 21

the negative charges are cleaved off of fibrinogen by thrombin, releasing fibrinopeptides. fibrin is now free to aggregate.

Front 22

thrombin

Back 22

protease activated in response to blood vessel dmg, that cleaves fibrinogen into fibrin

Front 23

fibrin

Back 23

has no negative charges, and is free to aggregate to form a clot

Front 24

soft clot

Back 24

non-covalent aggregations of fibrin

Front 25

hard clot

Back 25

stable clot, when glutamine and lysine groups on two fibrin monomers links covalently

Front 26

fibrin stabilizing factor (what does it do, what does it release, what is it activated by, and it's other 2 names)

Back 26

fibrinoligase
factor XIII
enzyme that catalyzes covalent linking between gln and lys groups on fibrin monomers to form a hard clot. releases an amine group off of glutamine.

activated by thrombin

Front 27

what type of protease is thrombin?

Back 27

serine protease (has crucial serine at active site)

Front 28

where does thrombin usually cleave?

Back 28

Arg-X or Lys-X bonds, especially if Arg/Lys is preceded by Pro

Front 29

how is thrombin "made"?

Back 29

it is formed from zymogen PROthrombin, and in response to blood cessel damage, it is cleaved to form active thrombin (cleavage reaction is catalyzed by factor Xa, also a serine protease, and cofactor Va)

Front 30

factor Xa does what and is what kind of enzyme

Back 30

serine protease, catalyzes cleavage of prothrombin to thrombin

Front 31

how is factor X activated? (2 ways)

Back 31

1) activated by protease factor VIIa in extrinsic pathway
2) activated by Factor IXa in the intrinsic pathway

Front 32

extrinisc pathway (what it requires)

Back 32

initiation requires protein called tissue factor (bound to cell surfaces that lie beneath the vessel walls, ergo does not come in contact with blood unless there is dmg)

Front 33

intrinsic pathway (what it requires)

Back 33

initation requires only an anionic surface (could be cell membranes beneath blood vessel walls or walls of glass test tube)

Front 34

what is the purpose of tissue factor and where is it located?

Back 34

TF is bound to membranes of cells beneath the blood vessel walls, and binds and activates factor VII (VII* -->similar to VIIa, but is not cleaved)

Front 35

VII* (what is it, what does it do)

Back 35

factor VII bound to TF; same function as VIIa but not cleaved. VII* cleaves X-->Xa, which, along with cofactor Va, cleaves prothrombin to thrombin.

Front 36

effects of thrombin on VII

Back 36

thrombin, which is generated by VII* via cleavages of Xa, has a positive feedback effect on VII in that it cleaves VII-->VIIa, which then makes more Xa. this is because we need blood to clot quickly.

Front 37

extrinsic pathway is involved with what factors and proteins?

Back 37

TF, VII (VIIa, VII*), X-->Xa, Va, prothrombin-->thrombin

Front 38

in the intrinsic pathway, what adheres to what initially?

Back 38

factor XII (which is activated by binding), HMK-PreKK, and HMK-XI adhere to exposed anionic cell surfaces (cell membrane below vessel wall)

Front 39

factor XII-->XII*

Back 39

XII is activated to XII* upon binding with anion cell surface

Front 40

PreKK

Back 40

Prekallikrein

Front 41

HMK

Back 41

high molecular weight kininogen

Front 42

Factor XII* catalyzes what? (and what is the subsequent step in the intrinsic pathway)

Back 42

formation of kallikrein from PreKK, which then cleaves XII-->XIIa.

Front 43

what does XIIa do

Back 43

cleaves XI-->XIa

Front 44

what does XIa do

Back 44

cleaves IX-->IXa (not X!!)

Front 45

what does IXa do?

Back 45

with cofactor VIIIa and vWF, IXa cleaves X-->Xa, which then cleaves prothrombin to thrombin with cofactor Va

Front 46

everything is localized in the extrinsic/intrinsic pathways except... (hint: how are intrinsic and extrinsic pathways connected)

Back 46

thrombin, which is free, meaning thrombin made from intrinsic pathway can go activate extrinsic pathway

Front 47

what components are involved in intrinsic pathway?

Back 47

XII-->XII*-->XIIa, HMK-preKK-->KK, HMK-XI-->XIa, IX-->IXa, X-->Xa, prothrombin-->thrombin, cofactors VIIIa and vWF

Front 48

what is the purpose of the complexity of coagulation pathways?

Back 48

amplification
one molecule of XIIa can cleave many molecules of XI-->XIa, which can then cleave many moelcules each of IX-->IXa...etc.

Front 49

thrombin catalyzes...(5)

Back 49

1) conversion of fibrinogen to fibrin
2) activation of fibrin stabilizing factor (factor XIII)
3) activation of factor VII
4) activation of protein cofactor V and VIII
5) activation of thrombin receptor, a platelet binding protein

Front 50

cofactor VIIIa

Back 50

used by IXa to convert X-->Xa along with vWF

Front 51

cofactor Va

Back 51

used by Xa to cleave prothrombin to thrombin

Front 52

thrombin receptor (regarding it's name, what does it do and where is it located)

Back 52

bad name; only binds to thrombin in order to be cleaved and activated, then it binds to platelets for the majority of the time
binds platelets and is located on the underside (?) of vessel walls (only exposed in damaged ones)

Front 53

things secreted by platelet after binding to thrombin receptor (6)

Back 53

thromboxane A2
vWF
serotonin
growth factor
some V
some xiii

Front 54

thromboxane A2

Back 54

recruits more platelets to dmg site for clotting

Front 55

vWF (2)

Back 55

von willebrand's factor
helps cofactor VIIIa bind to IXa
also helps platelets bind collagen

Front 56

serotonin

Back 56

released by platelets
increase vasoconstriction

Front 57

growth factor

Back 57

repair of blood vessel wall

Front 58

factor XIII

Back 58

soft-->hard clot
fibrin stabilizing factor

Front 59

which factors/proteins contain multiple gamma-carboxylated glutamyl residues, and why?

Back 59

prothrombin, X, VII (extrinsic), IX (intrinsic)
glutamyl has negative side-chain which binds Ca++ to permit anchoring of proteins to the anionic membranes. this allows X to be in proximity to prothrombin, and VII/IX to be in proximity to X to activate.

Front 60

Gla

Back 60

abbreviation for gamma-carboylated glutamate

Front 61

role of calcium ions (2)

Back 61

bind Gla residues of several clotting factors (helps factors associate with cell membranes at damage site to increase efficiency of proteolysis)

bind several clotting factors at sites other than Gla residues to serve as cofactor for catalysis (not sure of mechanism)

Front 62

ways to inactivate blood clotting cascade (3)

Back 62

Thrombomodulin-thrombin complex and protein C

antithrombin III

anticonvertin (aka TFPI)

Front 63

Thrombomodulin- what is it? 2 ways it works

Back 63

integral membrane protein expressed on in tact endothelial cells
1) decreases thrombin's affinity for fibrinogen
2) increases thrombin's affinity for protein C

Front 64

protein C pathway

Back 64

thrombomodulin bound to thrombin turns it into an anticlotting protein. the complex catalyzes the proteolysis of protein C-->Ca. Ca (along with protein Sa as a cofactor) cleaves Factor Va and VIIIa into inactive peptides.

Front 65

how is the stoppage of clotting regulated (so that you don't stop clotting at damaged sites?)

Back 65

since thrombomodulin is attached only to in tact endothelial walls, thrombin only becomes anticoagulative if it moves away from site of damage

Front 66

antithrombin III

Back 66

inhibits thrombin, Xa and all other proteases of blood clotting cascade except VIIa
serpin

Front 67

what enhances antithrombin III

Back 67

binding to heparin, a polysaccharaide produced by mast cells in response to injury

Front 68

anticonvertin (physical properties, what is it, how does it work, what else is it known as)

Back 68

a.k.a. tissue factor pathway inhibitor
protein with 2 domains
inhibits both factor VIIa and Xa, but VIIa is only inhibited if Xa is bound to TFPI.
stimulates internalization of VIIa by endocytosis

Front 69

fibrinolysis (and general pathway)

Back 69

dissolution of blood clots (thrombi)
fibrin is catalyzed by protease plasmin to soluble fibrin fragments

Front 70

plasmin (where does it come from)

Back 70

proteolysis of plasminogen precursor by Tissue plasminogen activator (TPA)

Front 71

TPA (what is it, clinical uses, regulation)

Back 71

tissue plasminogen activator
regulated by TPA inhibitors
catalyzes plasminogen into plasmin for clot breaking
used in stroke treatment to dissolve ischemic clots before onset of infarction (within ~3 hours)

Front 72

hemophilia A is a result of..

Back 72

deficiency of VIII

Front 73

hemophilia B is a result of...

Back 73

deficiency in IX

Front 74

genetics of hemophilias

Back 74

X-linked
more common in males

Front 75

role of vitamin K in blood clotting

Back 75

carboxylates glutamyl residues on clotting proteins, so that they can bind to Ca++, and then bind to cellular membranes to increase efficiency

Front 76

probable reaction mechanism for Vit K mediated gamma-carboxylation of glutamyl

Back 76

vit K dihydroquinone--O2-->vit k aldoxide (VERY strong base) pulls off H from gamme CH2 on glutamyl-->glutamyl now has a carbonide group which is very attracted to partial positive charge on C of CO2-->vit k aldoxide releases H2O and becomes vit K epoxide

Front 77

what is consumed and released in the vit K rxn

Back 77

CO2, O2 "consumed", H2O released

Front 78

how is vit K recycled?

Back 78

vit K epoxide-->dithiol dependent vit K epoxide reductase-->gets 2 H's from 2 sulfydryl groups (not sure form where)-->vit K dione-->same thing with dithiol-dependent vit K dione reductase (add 2 Hs and reduce ketone groups)-->vit K dihydroquinone

Front 79

individuals who are at increased risk for thrombosis (heart attack, stroke) are sometimes treated with one or more of the following...(3)

Back 79

anticoagulants: warfarin, aspirin, heparin (IM)

Front 80

warfarin (structure, mechanism, clinical use, high doses?)

Back 80

similar in structure to vit K
high doses = rat poison
act as competitive inhibitor of epoxide reductase
if prescribed, patient is told not to change eating habits (so as not to alter vitamin K intake)

Front 81

aspirin (generic name too, what does it do)

Back 81

acetylsalicylic acid
good acetylating agent, meaning it can donate acetyl groups to side chains with "OH" (serine, threonine, phenylalanine) non enzymatically

Front 82

heparin (what is it, how is it administered)

Back 82

IM, because it is a polysaccharide it will break down if taken orally
binds antithrombin III and improves it's anti-clotting, inhibitory ability against thrombin and other clotting factors.

Front 83

what specifically is the mechanism of aspirin? (what residue)

Back 83

acetylates key serine residue on the active site of cyclooxygenase (COX) and inactivates it

Front 84

cyclooxygenase (COX)- where is it present, what does it do

Back 84

present in many cells including platelets and endothelial cells (line blood vessel).
catalyzes conversion of arachadonic acid into prostaglandin G2 (precursor of several other prostaglandins)

Front 85

prostaglandins- what are they

Back 85

short range chemical messengers (cell-to-cell)

Front 86

platelets

Back 86

cell "fragments" produced from precursor that had nuclei, but lost it.

Front 87

arachidonic acid in platelets

Back 87

a fatty acid that, when converted to prostaglandin G2, is further converted to more prostaglandins an thromboxanes, which promote blood clotting and vasoconstriction.

Front 88

arachidonic acid in endothelial cells

Back 88

AA-->prostaglandins and prostCYCLINS, which inhibit blood clotting and inhibit vasoconstriction

Front 89

so why does aspirin only affect thromboxane/prostaglandin levels in the platelets?

Back 89

because endothelial cells have nuclei, so they can continually replenish the lost COX from aspirin. aspirin merely shifts function of AA from clot promoting to clot inhibiting.

Front 90

why do you have to keep taking aspirin to prevent clotting (as opposed to take once, and stop one you're better)

Back 90

you keep making new platelets, so you have to keep up the therapy

Front 91

main mechanism of heparin

Back 91

binding to antithrombin changes the conformation so that it fits better into thrombin (inhibitor), preventing it from cleaving fibrin from fibrinogen.

Front 92

major protein within RBC (erythrocytes)

Back 92

hemoglobin- oxygen transport protein

Front 93

hemoglobin structure and subunits

Back 93

globular
tetramer (dimer of heterodimers)
x2y2 (x may be alpha or zeta, y may be beta, delta, gamma, or epsilon)

Front 94

a2b2 (3)

Back 94

hemoglobin A1 (HbA1 or just HbA)
major hemoglobin in healthy adults
95-97% of adult Hb

Front 95

a2d2 (3)

Back 95

hemoglobin A2 (HbA2)
minor hemoglobin in healthy adults
~3% of total Hb

Front 96

a2g2 (2)

Back 96

fetal hemoglobin (HbF)
~1% of adult Hb as well

Front 97

zeta2epsilon2

Back 97

embryonic hemoglobin (HbE)
not found in adults

Front 98

which Hb is found in healthy adults?

Back 98

HbA1(95-97%), HbA2(3%), HbF (1%)

Front 99

example of subclass of HbA (and what it is, and what it is used for)

Back 99

HbAc
C stands for "carb" because it is glycosylated
very clinically important- if you have increase in blood glucose, you will have increase in HbAc, and this is used to monitor diabetics for compliance.

Front 100

heme

Back 100

each of the 4 subunits of hemoglobin contain this molecule, in their hydrophobic pokcet

Front 101

what is heme made up of and what is function of each? (2)

Back 101

protoporphyrin IX + Fe2+
Fe directly interacts with O2, and also interacts with His sidechain of Hb
protoporphyrin IX interacts with Lysine (NH3+) sidechains of hemoglobin subunit

Front 102

significance of oxidation state of iron

Back 102

Fe must be in the +2 (ferrous) state to bind oxygen

Front 103

color of deoxyhemoglobin

Back 103

dull red

Front 104

color of oxyhemoglobin (and why it changes color)

Back 104

bright red, due to O2 binding shifting electrons so light bends differently

Front 105

what compounds (3) can oxidize the Hb Fe+2? what does this form?

Back 105

O2 (if it just absconds with the electrons), benzocaine, nitrites (compounds with NO2-) derived from nitrates (NO3-)
forms methemoglobin (has iron in +3 ferric oxidation state)

Front 106

methemoglobin properties (2)

Back 106

does not bind O2
dull brown color

Front 107

NADH-cytochrome b5 reductase

Back 107

converts methemoglobin back to Fe2+

Front 108

why are cases of methemoglobinemia highest in the spring time?

Back 108

fertilizer is applied, and then it rains, so there is an increase in nitrates in the drinking water, which may also contain bacteria, which converts nitrates to nitrites.

Front 109

symptoms of methemoglobinemia (3)

Back 109

basically symptoms of O2 depression
1) increase heart rate
2) dizziness
3) loss of consciousness/eath

Front 110

why are infants particularly susceptible to methemoglobinemia? and what is this syndrome called in infants?

Back 110

blue baby syndrome (looks blue because brown color of methemoglobinemia through fair skin = blue???)
more common because baby has less NADH cytochrome b5 reductase than adults

Front 111

what is the treatment for methemoglobinemia? (2)

Back 111

remove source of hemoglobin oxidant
sometimes concurrent reducing agent (e.g. vitamin C) is given as well to promote reduction of methemoglobin to Hb.

Front 112

what causes conformational changes in oxyhemoglobin from deoxyhemoglobin?

Back 112

oxygen causes Fe2+ to be pulled towards the plane of the porphyrin ring, which drags the Histadine residue of Hb subunit with it. Displacement is transmitted to the Hb conformation resulting in displacement of other groups and disruption of ionic bonds.

Front 113

T-state

Back 113

tense state
lots of interactions between the 2 ab dimers.
binding of O2 is difficult (O2 given up easily)

Front 114

R-state (4)

Back 114

relaxed state
fewer interactions between 2 ab dimers
dimers have shifted with respect to each other
O2 binding is easier, therefore retained more tenaciously

Front 115

Hemoglobin function (2)
make sure to elaborate on specific levels, and other details.

Back 115

1) bind O2 in lungs where pO2 is high (~100 mmHg) and release bound O2 in capillary beds wher pO2 is low (~35 mmHg)
2) transport a small (~10%) amount of CO2 from where pCO2 is high (46 mmHg) to where pCO2 is lower in the lungs (40 mmHg). most CO2 is transported via bicarbonate.

Front 116

CO2 binding on hemoglobin
also what is the Hb called when bound to CO2

Back 116

CO2 does not bind to iron so is not competitive with O2. it binds to amino group on N-terminus of the globin chains.

carbamated hemoglobin

Front 117

oxygen binds to Hb with what kind of kinetics. what does this imply?

Back 117

positive cooperativity
therefore, Hb will bind O2 the best at places with high concentrations of O2 (e.g. the lungs) and releases when O2 is low as it does not bond as well.

Front 118

Keq's of deoxy, monoxy, dioxy, trioxy forms of Hb (arrange Keq's in order, K1, K2, K3, K4)

Back 118

K4 > K3 ~ K2 > K1

Front 119

pH effect (within physiological pH) on Hb ability to bind O2

Back 119

increase in pH (basic) = shift curve to the left on saturation (y) vs. pO2 levels (x)
decrease in pH (acidity) = shift to the right (decrease in O2 binding)

Front 120

physiological pH range

Back 120

7.0-7.6 with 7.35-7.45 being reference range

Front 121

reason for low pH causing decreased O2 binding in Hb

Back 121

histadine pKa is ~7.5
at this pH, it exists equally in a protonated and deprotonated form. the protonated form is what binds to an Aspartate residue and stabilizes the tense state. if we lower the pH, His shifts towards more of the protonated form, which favors the tense state, hence lower O2 binding.

Front 122

at basic pH...(location)...Hb binds...

Back 122

in the lungs, where pH is higher, Hb binds O2 more efficiently.

Front 123

why is pH lower in capillary bed of tissues than in lungs? (2)

Back 123

1) more CO2 in tissue because lungs are constantly expelling the CO2, whereas it can accumulate in tissue until it can be transported out.
2) active muscle produces lactic acid due to anerobic metabolism (lactic acid <--> H+ + lactate)

Front 124

why does more CO2 = more acidity?

Back 124

CO2 combines with H2O to become H2CO3 <--> H+ + HCO3-
more CO2 would drive reaction forward, producing more H+, and therefore lowering acidity.

Front 125

why does high pCO2 directly reduce ability of Hb to bind O2?

Back 125

increase in CO2 drives Hb to bind with CO2 and become carbamated Hb. the CO2 group on the N-terminus of beta globin chain interacts with lysyl residues on it's adjacent hetero-subunit alpha which promotes tense state.

Front 126

2,3 BPG (4)

Back 126

2,3 biphosphoglycerate
made by erythrocytes
is a glycerate + 2 phosphates
reduces ability of Hb to bind O2

Front 127

how does 2,3 BPG affect O2 binding of Hb?

Back 127

the 2 negative phosphate groups interact with positive charge on histadines on the beta subunits and link them together stabilizing the tense state and decreasing O2 binding.

Front 128

2,3 BPG effect on Hb O2 binding at high pO2

Back 128

2,3 BPG has no effects at high concentations of O2 (why? i dunno)

Front 129

do erythrocytes produce more or less 2,3 BPG when pO2 is low? (e.g. reduced lung capacity, or high altitude) and why?

Back 129

they make MORE, because to decrease O2 affinity of Hb means to increase efficiency of releasing O2 in capillaries, to make up for low external O2 levels.

Front 130

do erythrocytes make more or less 2,3 BPG when glycolysis is reduced? give an example of when this might occur and how you might compensate.

Back 130

less, since it is a byproduct of glycolysis.
an example is cold storage of blood for transfusion, which slows all pathways. to compensate, you also give BPG precursors along with the transfusion.

Front 131

relationship between glycolysis and 2,3 BPG

Back 131

2,3 BPG is a side product of glycolysis

Front 132

events in which levels of 2,3 BPG
are lowered or raised and the reasoning

Back 132

low pO2 (high altitude, reduced lung capacity)- raised because lack of O2 means erythrocytes want to increase efficiency of releasing O2 into capillaries (promote tense state)
reduced glycolysis- lowered, it is a byproduct

Front 133

positively charged residues are primarily on what subunit of Hb

Back 133

beta subunit

Front 134

HbF and 2,3 BPG

Back 134

HbF (a2g2) lacks the positively charged residues needed to bind to 2,3 BPH, which increases O2 affinity. fetuses need to be able to accept a lot of O2 from the parent's blood.

Front 135

factors that decrease affinity of Hb for O2 (4)

Back 135

1) increase 2,3 BPG
2) increase in pCO2
3) decrease in pH
4) decrease in pO2 (due to positive cooperativity)

Front 136

what is another role of Hb besides transport? describe how it works in the lungs and in tissue.

Back 136

intracellular buffer
in tissue, high CO2 levels, which dissociate into bicarbonate and protons. protons can combine with deoxyHb in RBC which just released it's O2 (acting as a buffer).

in lungs, there is high O2 and low CO2, meaning the rxn is driven from bicarbonate + H+ to dissolved CO2. the HbH+ loses it's H+ and picks up the O2, buffering the loss of H+ in the formation of CO2.

Front 137

why does the pKa of Hb change in response to O2?

Back 137

due to particular His residue on b-subunit. in tense form, the positive charge on the NH of histadine gets it's share of electrons from a nearby Asp residue. this gives it a higher pKa as it does not want to give up it's H.

in the relaxed/O2 state, the Asp is no longer near the His, so the N+ is now taking electrons from it's connected H. This makes the H more likely to just dissociate without it's electrons (lower pKa, better acid)

Front 138

oxyhemoglobin has a ____ affinity for H+ than deoxyhemoglobin and is therefore a ____ acid.

Back 138

lower, stronger

Front 139

oxyhemoglobin has a ______ pKa than deoxyHb

Back 139

lower

Front 140

what happens to the excess HCO3- in tissue RBC as Hb picks up the H+ as a buffer?

Back 140

they leave the cell (exchange with a Cl-) and travel to the lungs where it is used to produce CO2 for expiration.

Front 141

myoglobin

Back 141

oxygen storage protein found in muscle. structurally similar to Hb subunits but does not associate into tetramers.

Front 142

graph of myoglobin O2 saturation vs. Hb O2 saturation in increasing concentrations of O2 and myoglobin vs. Hb affinity

Back 142

myoglobin is not sigmoidal, since it is only one subunit, it does not have (+) coop. however it does have a higher affinity for O2 than Hb.

Front 143

O2 consumption in muscle (myo vs. hb)

Back 143

O2 first comes from Hb in a working muscle, then from myoglobin (due to higher affinity)