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MedBiochem > quiz 2.1 O2 and CO2 > Flashcards

quiz 2.1 O2 and CO2 Flashcards

1
Q

exchange of gases between external and internal environment

A

ventilation

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2
Q

exchange of gas between tissue and blood

A

internal respi

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3
Q

how does blood and tissue exchange gases

A

diffusion

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4
Q

conserved amino acid in both hb and mb

A

his F8 and E7
phe CD1 and leu F4
gly B6

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5
Q

these amino acids in hb and mb are for heme contact (hydrophobic poket)

A

phe CD1 and leu F4

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6
Q

this amino acid in hb and mb allows the close approach of helices B and E

A

gly B6

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7
Q

compact globular protein with ____ amino acids folded in ____ right handed alpha helices A to H

A

myoglobin
153
9

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8
Q

approximately 75% of Hb is in the form of an

A

alpha helix

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9
Q

Hb has __ heme groups and therefore ___ oxygen binding sites

A

4

4

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10
Q

characteristics of Hb

A

64 kd

heterotetramer with 2 pairs of globin polypeptde chains

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11
Q

structure of HbA

A

alpha2/beta2

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12
Q

structure of Hb Gower1

A

zeta2/epsilon2

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13
Q

structure of Hb Portland

A

zeta2/gamma2

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14
Q

the prosthetic group of Hb and Mb located in the hydrophobic pocket

A

heme

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15
Q

structure of heme

A

protoporphyrin ring with bound iron

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16
Q

organic portion of heme

A

protoprphyrin ring

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17
Q

structure of protoporphyrin ring

A

4 pyrroles linked by methenyl bridges

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18
Q

groups/substituents seen in the structure of heme

A

propionate
vinyl
pyrrole

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19
Q

sharp bands seen when heme absorbs visible lights and read at 400nm absorpotin

A

Soret band

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20
Q

ano absorption binabasa heme

A

400nm

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21
Q

substituents attached to pyrolle

A

methyl
vinyl
propionate

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22
Q

iron in heme bind to how many ligands

A

6

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23
Q

ano ung 6 na ligands bound to iron ng heme

A

4 of 6 to N of pyrroles
5th to his F8
6th for oxygen

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24
Q

bond linkinf the first and second oxygen lies at what angle

A

121 degrees

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25
Q

the state aka deoxy conformation

A

Tense state

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26
Q

the state aka oxy conformation

A

Relaxed state

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27
Q

deoxyHb is stabilized in a constrained or tense configuration by

A

inter and intrasubunit salt bonds

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28
Q

oxygen binds to and pulls the iron toward where

A

the heme plane

resulting in the straightening of the dome shaped heme

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29
Q

angle of rotation of alpha2/beta2 during oxygenation

A

15 degrees

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30
Q

what is broken in the heme during oxygenation

A

8 salt bridges taht stabilize the T state

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31
Q

what is decreased in heme during oxygenation

A

size of central cavity

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32
Q

what is created during oxygention of heme

A

new hydrogen bonds in alpha1/bet2 interface

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33
Q

the iron in unoxygented Hb and Mb lies ____ outside the plane of the heme ring

A

.03 nm

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34
Q

puckering of the heme is directed where

A

towards proximal his F8

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35
Q

when oxygenated, the iron moves to within ___ of the heme plane

A

.01 nm

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36
Q

during deoxygenation, the beta chains rotate apart by approximately

A

.7 nm

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37
Q

the pasok of the heme into the plane during oxygenation si caused by what

A

stearic repulsion

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38
Q

the second oxygen is oriented _____ the distal his E7

A

away

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39
Q

partial pressure required for 50% saturation

A

P50

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40
Q

curve for myoglobin shows what shape

A

hyperbolic

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41
Q

P50 for myoglobin

A

2 mm

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42
Q

which has higher affinity, Mb or Hb

A

Mb @ 2mm P50

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43
Q

curve for hemoglobin shows what shape

A

sigmoidal

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44
Q

interaction where binding of O2 facilitates binding of additional O2 to other heme group

A

cooperativity

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45
Q

P50 for hemoglobin

A

26 torr

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46
Q

why sigmoidal ung hemoglobin

A

difficult binding of 1sy oxy
easy 2nd and 3rd
difficult for 4th

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47
Q

this provides info on the dgree of cooperativity

A

Hill coefficient

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48
Q

nH = 1 shows

A

no cooperativity

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49
Q

nH > 1.0 shows

A

positive coop

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50
Q

nH < 1.0 shows

A

neg coop

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51
Q

nH of Mb

A

1.0

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52
Q

nH of Hb

A

2.8

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53
Q

refers to the fold change in pO2 required to change Y =0.1 to 0.9 (10% saturation to 90%)

A

cooperativity index Rx

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54
Q

cooperativity index is computed from

A

nH

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55
Q

Mb Rx

A

81

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56
Q

Hb Rx

A

4.8

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57
Q

causes shift to the right

A

increase in temp, H protons, 2,3 BPG, altitude

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58
Q

binding of O2 to the T state causes concerted conformational change

A

Monod Wyman Changuex

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59
Q

allows a serial transformation of the subunits where there exist intermediate transformations between T to R states

A

Koshland Nemethy Filmer

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60
Q

the glycosylation of Hb requires the ___ type of rearrangement

A

Amadori

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61
Q

level of HbA1c reflect the mean blood glucose over ____ weeks because halflife of RBCs is 60days

A

6-8wks

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62
Q

inherited anomalies of Hb synthesis resulting from mutation in the globin genes

A

hemoglobinopathies

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63
Q

cause of Hb S

A

glu6 to val

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64
Q

the replacing valine in position 6 produces ___ on teh exterior of the molecule

A

sticky patch

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65
Q

Hb S causes what shift

A

rightward

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66
Q

P50 in Hb S

A

31

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67
Q

which does not contain the sticky patch in transfused blood

A

deoxy Hb

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68
Q

oxygenation has what effect on Hb S

A

masking of complimentary site thus prevention of sickling

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69
Q

characterized by reduced of one or more globin synthesis

A

thalassemia

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70
Q

characteristic products of alpha thalassemia trait

A

Hb Bart

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71
Q

ilang deletion sa alpha thalassemia-2

A

one

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72
Q

ilang deletion sa alpha thalassemia trait

A

2

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73
Q

ilan deletion sa Hgb H

A

3

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74
Q

absence of alpha chains what dse

A

Hydrops fetalis

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75
Q

total absence of beta chains what dse

A

thalassemia major

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76
Q

major end product of aerobic metab

A

CO2

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77
Q

normal aerobic conditions generate more than _____ of CO2 per day

A

13mol (.5 to 1kg)

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78
Q

process in transportation of CO2 from tissue to lungs thru circulation

A

convection

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79
Q

CO2 is _________ than O2

A

20x more soluble

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80
Q

formed from the rxn of CO2 and H20 catalyzed by the enzyme carbonic anhydrase

A

HCO3- bicarbonate

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81
Q

enzyme that catalyzes formation of HCO3-

A

carbonic anhydrase

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82
Q

percentages of CO2 in body

A

10% as dissolved
20% with proteins
70% bicarbonate

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83
Q

formed from the rxn of CO2 with the amino groups of proteins (like Hgb) within erythrocytes

A

carbaminohemoglobin

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84
Q

CO2 combines with the what of proteins

A

terminal NH2 (uncharged, aliphatic)

85
Q

____________ forms carbamino mmroe readily thatn ________

A

deoxy Hb; oxy Hb

86
Q

pH within RBC in carbamino form is

A

approx. 7.2

87
Q

major acid produced by the body and acts as its own buffer

A

carbonic acid

88
Q

makes hemoglobin an important buffer

A

isohydric exchange

89
Q

describes how oxygen conc determines affinity for CO2

A

Haldane effect

90
Q

hgih pCO2 unloads O2

A

Bohr effect

91
Q

low pCO2 loads O2

A

reverse Bohr

92
Q

high pO2 unloads CO2

A

Haldane

93
Q

low pO2 loads CO2

A

reverse Haldane

94
Q

oxygen shifts the CO2 curve to

A

right

95
Q

CO2 curve when PaO2 is @ 95 mmHg

A

lower curve (down, right)

96
Q

CO2 curve when PvO2 is @ 40 mmHg

A

upper curve (up, left)

97
Q

in CO2 dissoc curve, CO2 content in tissues move from point ___ to ____

A

A to V

98
Q

in CO2 dissoc curve, CO2 content in lungs move from point ___ to ___

A

V to A

99
Q

chloride shift aka

A

hamburger effect

100
Q

function of chloride shift

A

maintains electrical neutralit/balance

101
Q

chloride shift is caused by exchange of what

A

bicarbonate forCL-

102
Q

chloride ions enter RBC to establish elec neutrality. what effect

A

Donnan effect

103
Q

chloride shift movement in tissues

A

influx of chloride

104
Q

chloride shift movement in lungs

A

efflux of chloride

105
Q

molecule that has a single unpaired electron in an orbital; highly reactive

A

radicals

106
Q

action of radicals

A

initiate chain rxns by stealing an electron from neighboring molecules

107
Q

free radicals are generated by

A

homolytic cleavage of covalent bonds
loss of a singl electron
addition of an electron

108
Q

biradical atom

A

oxygen

109
Q

how are the spins of the two solo electron of oxygen

A

parallel

110
Q

difficult flipping of an oxygen electron

A

spin restriction

111
Q

O2 is capable of accepting how many electrons

A

4

112
Q

once O2 accepts one electron, it becomes

A

superoxide

113
Q

theory states that an electron cannot readily oxidize a covalent bond because the other electron needs to flip its spin

A

antibonding

114
Q

major oxygen metabolites produced by one-electron reduction of oxygen

A

ROS

115
Q

superoxide
H2O2
hydroxyl free

which is not a radical

A

H2O2

116
Q

eto ung tuloy tuloy na pagbuo ng radicals kapag steal nang steal ung dating radicals

A

cytotoxic oxidative chain rxn

117
Q

formed from free O2 by donating an elecctron to another free radical

A

sueproxide

118
Q

why can’t superoxide diffuse far from site of origin

A

limited lipid solubility

119
Q

superoxide is produced where or when

A

ETC

120
Q

generation of hydroxyl free rads by rxn with a transition metal

A

fenton rxn

121
Q

rxn of superoxide with H202 to form other ROSs

A

Haber Weiss rxn

122
Q

precursor of the powerful oxidzing agent HOCl

A

H202

123
Q

powerful ozidizing agent from H2O2

A

HOCl

124
Q

rxn when forming H2O2 from O2

A

dismutation rxn

125
Q

most toxic ROS

A

hydroxyl radicals

126
Q

rxns involved in producing hydroxyl radicals

A

Fenton nd Haber Weiss

127
Q

hydroxyl radicals are very damaging because of this intermediate effect

A

initiation of lipid peroxidation

128
Q

cis or trans ano mas common na maging radical

A

cis

wtf question

129
Q

HOCl is produced in neutrophils during what

A

respiratory burst

130
Q

toxicity of HOCl is thru

A

halogenation and oxidation

131
Q

how is HOCl formed

A

myeloperoxidase on CL ions in the presence of H2O2

132
Q

produced at high oxygen tension from absorption of UV light

A

O2 singlet oxygen

133
Q

sppin ng singlet oxygen

A

anti-parallel

134
Q

NO is produced by

A

nitric oxide sythase

135
Q

NO is synthesized from

A

argining

136
Q

anong type ung NO

A

type 2 inducible

137
Q

a strong oxidizing agent but not a free radical

A

ONOO peroxynitrite

138
Q

peroxynitrie is formed from

A

superoxide + nitric oxide

139
Q

kinds of sources of ROS

A

accidental
physiologic
deliberate
exogenous

140
Q

coenzyme Q is what kind of source ng rOS

A

accidental

141
Q

what ROS is formed in ETC or is an accidental byproduct

A

superoxide

142
Q

respiratory burst is what kind of source of ROS

A

deliberate

143
Q

process in which cells consume large amounts of oxygen during phagocytosis and release ROS

A

respiratory burst

144
Q

how is ROS formed in NADPH oxidase

A

transfer of electron from NADPH to O2

145
Q

hydrogen peroxide is formed by what

A

superoxide dismutase

146
Q

the formation of HOCl from H2O2 is catalyzed by

A

myeloperoxidase

147
Q

oxidatively degrades the neurotransmitter dopamine and geenrate H2O2 at the mitochondrial membrane of certain neurons

A

monoamine oxidase

148
Q

generates H2O2 rather than FAD(2H) durind the oxidation of very long fatty acid chains

A

peroxisomal fatty acid oxidase

149
Q

an enzyme of purine degradation that can reduce O2 to superoxide or H2O2 in the cytosol

A

xanthine oxidase

150
Q

believed to be a major contributor to ischemia-reperfusion injury

A

xanthine oxidas

151
Q

xanthine oxidase is believed to be a major contribution to

A

ischemia-reperfusion injury

152
Q

formed as intermediates in the pathways for synthesis of many eicosanoids including leukotrienes and prostaglandins

A

lipid peroxides

153
Q

xeogenous sources of ROS

A 
ionizing radiation
tobacco
drugs
alcohol
inorganic particles
gases
154
Q

this drug has pro-oxidant activity

A

methotrexate

155
Q

iron deposition in smokers’ lungs can cause what rxn

A

Fenton

156
Q

an antibiotic that may be a source of ROS

A

nitrofurantoin

157
Q

chlorine radicals from CFCs are formed thru

A

photodissociation

158
Q

steps in membrane attack by lipid peroxy radicals

A

lipid peroxidation
propragation
degradation
termination

159
Q

in lipid eproxidation, where does free radicals extract hydrogena tom from

A

polyunsaturated lipids

160
Q

lipid radical reacts with O2 and forms what

A

lipid peroxy radical and lipid peroxide

161
Q

used as an indicator of fre radical damage in the body

A

malondialdehyde

162
Q

termination of the formation of lipid peroxy radicals are caused by

A

vit E and other lipid-soluble antioxidants

163
Q

what are the amino acids susceptible to hydroxyl radical attack and oxdiative damage

A 
proline
histidine
arginine
cysteine
methionine
164
Q

main cellular defenses against oxygen toxicity

A

cellular leve
antioxidant scavenging
nonenzymatic defense

165
Q

cellular level defense against oxygen toxicity

A

compartmentalization
metal sequestration
repair mechanism

166
Q

disabling iron to participate in Fenton rxn

A

iron sequestration

167
Q

what are the antioxidant scavenging enzymes

A

SOD
catalse
glutathione reductase
glutathione peroxidase

168
Q

this is the primary defense against oxidative stress because superoxide is a strong initiator of chain rxns

A

SOD

169
Q

three isoenzyme forms of SOD

A

cooper-zinc in cytosol
manganese in mitochondria
copper-zinc in extracellular

170
Q

heme-containing enzyme catalyzing dismutation of H2O2 into water and oxygen

A

catalase

171
Q

highest catalase activity can be seen in

A

kidney and liver

172
Q

catalse is found principally where

A

peroxisome

173
Q

which is better? catalase or glutathione peroxidase? and why

A

gluta bcoz no oxygen formed from H2O2

174
Q

amino acids in glutathione

A

glucine
cysteine
glutamic

175
Q

catalyzes the reduction of hydrogen peroxide and lipid peroxides by glutathione

A

glut peroxidase

176
Q

complete name of glutathione

A

gamma-glutamylcysteineylglycine

177
Q

the reactive _______ in glutathione peroxidase reduce H2O2 to water and lipid peroxides to non-toxic alcohols

A

sulfhydryl groups

178
Q

what happens to sulfhydryl groups during action of glutathione peroxidase

A

oxidized to disulfide

179
Q

glutathione peroxidase is found primarily in

A

cytosol and mitochondria

180
Q

reduces oxidized glutathione (GSSG) back to the reduced form

A

glutathione reductase

181
Q

major source of glutathione reductase

A

PPP/HMP

182
Q

glutathione reductase contains ______ and catalyzes transfer of electrons from NADPH to the disulfide bond of GSSG

A

FAD

183
Q

a common structure in non-enzymatic antioxidants

A

conjugated double bond system that may be an aromatic ring

184
Q

most widely distributed antioxidant in nature

A

vit E (tocopherol)

185
Q

among toxxopherols, this is the most potent

A

alpha tocopherol

186
Q

fully oxidized form of tocopherol

A

tocopheryl quinine

187
Q

tocopheryl radical is stabilized by the fully substituted benzoquinone ring and does not propagate the radical rxn, there it is an effective __________

A

radical trap

188
Q

hydrophilic vitamin and best functions in aqueous environment

A

vit C

189
Q

these indirectly scavenges oxygenf ree radicals b recycling tocopherol to the reduced form

A

chain breaking antioxidant

190
Q

term applied to the beta carotene

A

carotenoids

191
Q

prcursor of vit A

A

beta carotene

192
Q

eaxmple of chain breaking antioxidants

A

vit C

carotenoids

193
Q

action of carotenoids as antioxidant

A

reacts with lipi peroxidation products to terminate rxn

194
Q

what scavenges singlet oxygens

A

carotenoids

195
Q

a toxic effect of beta carotene

A

yellowing of skin @ >20mg/day

196
Q

group of strucutrally similar compounds containing two spatially separate aromatic rings

A

flavonoids

197
Q

sample sources of lavonoids

A

red win
green tea
chocolate

198
Q

action of flavonoids

A

inhibits xanthine oxidase
chelate Fe and Cu
doantes electrons to superoxide or lipid peroxy radicals
maintenance of vit E

199
Q

endogenous antioxidants

A

uric acid

melatonin

200
Q

uric acid accounts for the major ____________________ of plasma

A

free radical trapping capacity

201
Q

secretory product of pineal gland

A

melatonin

202
Q

functions in the circadian rhythm, light dark signal transduction and sleep induction

A

melatonin

203
Q

effectiveness of melatonin as antioxidant is due to its

A

lack of pro-oxidant activity

joint hydrophilic phobic nature

204
Q

action of metal chelators as antioxidants

A

bind iron and copper

205
Q

example of metal chelators

A

ferritin
transferrin
cerulopasmin
albumin

206
Q

transferrin binds

A

iron

207
Q

multi subunit protein shell surrounding iron core

A

ferritin

208
Q

convert Fe2 to 3

A

ceruloplasmin

209
Q

binds copper tightly and iron weakly

A

albumin

MedBiochem (16 decks)

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