Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

biochemistry > chapter 10- hemoglobin and myoglobin > Flashcards

chapter 10- hemoglobin and myoglobin Flashcards

1
Q

is the heme group conjugated or un-conjugated?

A

conjugated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

hemoglobin contains how many heme groups?

A

four; one on each of the sub units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

myoglobin contains how many heme groups?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

molecular oxygen binds how to the Fe(II) atom in heme?

A

irreversibly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Heme is composed of an organic _____ and a ____ atom

A

an organic protoporphyrin and a metal atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How many oxygen molecules does myglobin bind to reversibly?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How many oxygen molecules does hemoglobin bind to reversibly

A

four

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

hemoglobin is used to transport oxygen over _____ distances such as from the ______ to the _______

A

large distances such as from the lungs to all tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Myoglobin is used to transport oxygen over_____ distances such as ______ and behaves as _______

A

over short distances such as in the muscles and behaves as local “storage” reservoir of oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

heme is what type of group

A

prosthetic group which contains a central iron atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Each iron atom can form ____ coordination bonds

A

six coordination bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How many of iron’s bonds are with oxygen?

A

one of six of iron’s bonds are with oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

A heme group contains 4_____ that are liked via _____

A

pyrrole rings linked via methene (methine) bridges.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The T state of hemoglobin has _____ affinity for oxygen than R state because ______

A

T state has lower oxygen affinity than R state because the Fe-Nporphyrin bonds are longer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The fifth bond of iron in the heme group forms with ______

A

an imidazole ring of a histidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The prosthetic group of hemoglobin and myoglobin is ______

A

heme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The organic ring component of heme is _____

A

porphyrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Under normal conditions the central atom of heme is

A

Fe2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How many bonds does the iron of heme have to the nitrogen in the porphyrin?

A

four

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

The iron of heme has _____ bonds. What are these bonds to?

A

4 to nitrogen in porphyrin
1 to oxygen
1 to imidazole ring of histidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In deoxyhemoglobin the central atom is what?

A

displaced 4 A out of the plane of the porpyhrin ring system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Does hemoglobin of myoglobin have a higher oxygen affinity?

A

Myoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which molecule (hemoglobin or myoglobin) delivers oxygen more efficiently to tissues?

A

hemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The binding pattern of hemoglobin is considered (cooperative or uncooperative)

A

cooperative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

As oxygen binds to hemoglobin what happens to the molecule?

A

It changes the shape of the molecule, further enhancing oxygen binding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the shape of the oxygen dissociation curve of the Hemoglobin?

A

Sigmoidal in shape (“S”-shaped)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What shape is the dissociation curve for myoglobin?

A

hyperbolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

To what molecule (hemoglobin or myoglobin) does oxygen bind irreversibly?

A

neither

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

To what molecule (hemoglobin or myoglobin) does carbon monoxide bind at an allosteric site, lowering oxygen binding affinity?

A

Neither

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

The graph of the hill plot has an x-axis of ______ and a y-axis of ______

A

x-axis of log (pO2)

y-axis of log ((Yo2)/(1-Yo2))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

In the hill plot if n is >1 than ______

A

oxygen binding is positively cooperative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

In the hill plot if n = 1 than _____

A

oxygen binding is cooperative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

In the hill plot if n is < 1 than ____

A

oxygen binding is negatively cooperative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

When oxygen binds to hemoglobin it causes a ________ that breaks _____, lowering _____ of _____ which where involved in ______.

A

causes a conformation change that breaks several salt bridges, lowering pka of the basic amino acids involved in the salt bridges.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Oxyhemoglobin can be a simple buffer at a pka of ____; what is this equation?

A

6.7;

HHbO2 (H+) + HbO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

deoxyhemoglobin can be a simple buffer at a pka of ____; what is this equation?

A

7.8;

HHb (H+) + Hb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Oxyhemoglobin and deoxyhemoglobin can act as a simple buffer as a result of what?

A

oxygen binds to hemoglobin salt bridges to break lowering the pka of the basic amino acids involved in the salt bridges.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The inverse relationship between the binding H+ and O2 is the ______

A

Bohr effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

The Bohr effect does what?

A

helps maintain a constant blood pH as CO2 is converted to HCO3- in tissues and as HCO3- is converted back to CO2 in the lungs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

The O2 _____ in the lungs leads to the ______(release/uptake) of H+

A

binding in the lungs leads to the release of H+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

The O2 _____ in the tissues leads to the _____ (release/uptake) of H+

A

release in the tissues leads to the uptake of H+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

deoxyhemoglobin is responsible for protein ______ in the _____when pH is _____

A

protein binding in the tissues when pH is more than 7.4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

oxyhemoglobin is responsible for protein _____ in the ______ when pH is ____

A

protein dissociation in the lungs when pH is less than 7.4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

At a pH of _____ oxygen _____ occurs in the lungs which leads to_____

A

at a pH of 7.4 oxygen binding occurs which leads to a decrease in pH (not of the blood) and leads to oxyhemoglobin protein dissociation in the lungs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

At a pH of _____ oxygen ______ occurs in the tissue which leads to _______

A

at a pH of 7.4 oxygen dissociation occurs in the lungs leading to an increase in pH and leads to protein binding of deoxyhemoglobin in the tissues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

If the adult hemoglobin (HbA) is replaced by an infant’s fetal hemoglobin what would be expected to occur?

A

There will be a shift to the left of the hemoglobin curve meaning that at a given pO2 there will be a higher fraction of occupied binding sites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What does a leftward shift of the hemoglobin curve indicate?

A

That at a given pO2 there will be an increase in the fraction of occupied binding sites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Since the replacement of adult hemoglobin(HbA) with infant’s fetal hemoglobin causes a ____ curve shift which indicates what?

A

causes a leftward curve shift which indicates that infant’s fetal hemoglobin has a higher fraction of occupied binding sites than adult hemoglobin (HbA) at a given pO2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

If hemoglobin is isolated from RBC and stripped of 2,3-bisphosphoglycerate what would be expected to occur?

A

There will be a leftward shift of the hemoglobin curve meaning that at a given pO2 there will be a higher fraction of occupied binding sites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Since the removal of 2,3-bisphosphoglycerate from hemoglobin causes a _____ this indicates what?

A

causes a leftward hemoglobin curve shift which indicates that 2,3-bisphosoglycerate decreases the affinity oxygen binding to hemoglobin since when it is removed hemoglobin has a higher fraction of occupied binding sites at a given PO2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

If Tetrameric hemoglobin is dissociated into its subunits causes a ______ meaning ______.

A

leftward shift in the hemoglobin curve meaning that at a given pO2 the fraction of occupied binding sites of hemoglobin increases when it is dissociated into its subunits.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What does a rightward shift of the hemoglobin curve indicate?

A

It indicates that at a given pO2 the fraction of occupied binding sites decreases (thus affinity decreases)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

If the blood pH drops from 7.4 to 7.2 this causes what to happen to the hemoglobin curve?

A

A rightward shift indicating that the blood now has a decreased infinity for binding oxygen; a decrease in fraction of occupied binding sites at a given pO2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

If the CO2 concentration in the blood increases this causes what to happen to the hemoglobin curve?

A

A rightward shift of the hemoglobin curve meaning the affinity of oxygen for hemoglobin has decreased; at a given pO2 the fraction of occupied binding sites has decreased

55
Q

Since a decrease in blood pH caused a ____ shift in the hemoglobin graph this indicates _____

A

rightward shift in the hemoglobin curve indicates that pH decreases the affinity of oxygen to hemoglobin

56
Q

Since the increase in concentration causes a ____ shift in the hemoglobin graph this indicates ______

A

Rightward shift in the hemoglobin curve this indicates that an increase in concentration decreases the affinity of oxygen to hemoglobin .

57
Q

If the concentration of 2,3 -bisphosphosphoglycerate increases during the acclimation to high altitudes this causes a ______ to happen to the hemoglobin shift

A

Causes a rightward shift of the hemoglobin curve. Meaning that it decreases the affinity of oxygen binding to hemoglobin; at a given pO2 the occupied binding sites has decreased.

58
Q

Since an increase of 2,3- bisphosphosphoglycerate causes a ______ to occur this indicates that….

A

causes a rightward curve shift of hemoglobin which indicates that an increase in 2,3-bisphosphoglycerate causes a decrease in the affinity of oxygen to hemoglobin.

59
Q

hemoglobin is a _____ while myoglobin is a ______

A

hemoglobin is a heterotetramer

myoglobin is a monomer

60
Q

By itself heme (is/is not) a good oxygen carrier. It needs what

A

heme by itself is not a good oxygen carrier instead it needs to be part of a larger protein to prevent oxidation of the iron

61
Q

Molecular oxgen binds _____ to Fe2+ in heme

A

reversibly

62
Q

The heme prosthetic group is located ______ in the protein, with _____ groups exposed ______

A

The heme prosthetic group is located at the hydrophobic cleft in the protein, with propionate (propanoate) groups exposed at the surface.

63
Q

Fe2+ is bound to hemoglobin when hemoglobin is in _____

A

R state

64
Q

Oxygen is bounded to hemoglobin when hemoglobin is in _____

A

R state

65
Q

Is the main conformation of deoxyhemoglobin R state or T state

A

T state

66
Q

Is the main conformation of oxyhemoglobin R state or T state

A

R state

67
Q

Oxygen binding stabilizes the _____

A

R state

68
Q

As CO2 binds to hemoglobin, the affinity of hemoglobin for O2 ____

A

decreases

69
Q

How does Fe3+ bind oxygen

A

It does not bind oxygen

70
Q

When oxygen binds to the T state it causes a _____

A

causes a conformation change to the R state.

71
Q

2,3- Bisophosphoglycerate binds between _____ in the _____ state and stabilizes the T state.

A

binds to the cavity between Beta units of hemoglobin in the T state and stabilizes the T state.

72
Q

How is 2,3- Bisophosphoglycerate prevented from binding?

A

The conversion to the R state changes the shape and size of the cavity which prevents the binding of 2,3-bisphoglycerate.

73
Q

_____ state has higher affinity for oxygen

A

R state

74
Q

_____ state has lower affinity for oxygen

A

T state

75
Q

which have shorter Fe-oxygen bond (R state or T state)

A

R state compared to T state

76
Q

When heme groups binds oxygen the Fe-Nporphyrin bonds shorten doing what to the iron atom?

A

It moves the iron ion into the plane of the porphyrin ring.

77
Q

Why can we say myoglobin has higher oxygen affinity based on a graph than hemoglobin?

A

myoglobin has hyperbolic curve while hemoglobin has a sigmoidal (S-shaped). therefore at all oxygen concentrations the myoglobin has a higher saturation than does hemoglobin thus myoglobin has the higher oxygen affinity.

78
Q

In deoxyhemoglobin the sixth coordination site is ______ and the iron atom is ______

A

unoccupied (lacks oxygen) and the iron atom is out of the plane of the porphyrin ring.

79
Q

When oxygen occupies the sixth coordination site, the iron atom ________

A

the iron atom moves into the plane as the conformation of the protein changes.

80
Q

Why is hemoglobin more efficient at delivering oxygen then myoglobin?

A

Hemoglobin has a lower affinity for oxygen than myoglobin

81
Q

Hemoglobins _____ affinity for oxygen allows it to release _____ in _____ concentration

A

low affinity for oxygen allows it to release oxygen in low oxygen concentrations.

82
Q

when is oxygen released from myoglobin?

A

when the oxygen concentration falls to very low levels in the muscle tissues (skeletal and cardiac)

83
Q

In the hill plot what is YO2 equal to?

A

number of occupied oxygen binding sites / the total number of binding sites on the protein.

84
Q

The hill plot for myoglobin is ____ while the plot for hemoglobin is ____

A

hill plot for myoglobin is linear while the plot for hemoglobin is not linear.

85
Q

The theoretical maximum value of n for hemoglobin is _____ but is this value ever reached?

A

max n value is 4 which would indicate complete cooperation between all subunits meaning all oxygen molecules would bind simultaneously. However the observed value is always less than 4 (the limit is never actually reached)

86
Q

R and T state differ in ____

A

quaternary structure; they differ in a shift of the subunit positions relative to each other.

87
Q

What will cause a hemoglobin curve shift to the right?

A

decreasing oxygen affinity and/or increases T state

88
Q

In hemoglobin as oxygen pressure ____ and oxygen binds it causes ____ exposing _____ which account for ____

A

as oxygen pressure increases and oxygen binds it causes a conformation shift exposing more R state binding sites which accounts for the “S shape” nature of the curve.

89
Q

The Bohr effect states that hemoglobin binding affinity is and pH is _____ to CO2

A

inversely proportional

90
Q

As there is a ____ in acidity causes a increase in protons in the blood that ____

A

increase in acidity ( decrease in pH) causes an increase in protons in the blood that compete with oxygen in binding.

91
Q

heme is a planar group with both ___ and ____ functions

A

polar and non polar functions

92
Q

The polar propionate groups of heme are ___

A

at the surface of the protein

93
Q

The nonpolar groups of the heme are _____

A

buried

94
Q

Both myoglobin and hemoglobin require ____ to bind and carry oxygen

A

heme

95
Q

What would happen if heme was not part of a protein?

A

The O2 binded to heme would oxidize Fe2+ to Fe3+ (which cannot bind oxygen), through a heme- O2-heme- intermediate. This intermediate is sterically hindered by the interaction between the protein and the oxygen-carrying heme group.

96
Q

Hemoglobin is a heterotetramer with ___ chains and ___chains

A

2 alpha chains

and 2 beta chains each subunits contains a heme group.

97
Q

Myoglobin is a monomer with ____ chain

A

one polypeptide with one heme

98
Q

Normal hemoglobin is designate ____ while sickle cell hemoglobin is designated ____

A

normal hemoglobin (HbA) and sickle cell hemoglobin (HbS)

99
Q

The mutated form of hemoglobin in sickle-cell anemia results from the replacement of ____ by a _____ at position ____ in the ____ of a protein

A

the replacement of the charged amino acid glutamate with the nonpolar residue valine at position 6 in the Beta chain of the protein

100
Q

under conditions of low oxygen HbS does what?

A

aggregates and distorts the RBC into a sickle shape.

101
Q

Sickled RBC are relatively _____ (flecible/inflexible) and may do what to the capillary beds causing ____.

A

relatively unstable and may clog the capillary beds causing pain and tissue damage.

102
Q

How does sickled RBC lead to anemia

A

they have a shorter life span.

103
Q

what is the residue that replaces glutamate to produce HbS

A

valine

104
Q

What other residues can replace glutamate to produce a similar sickle cell effect

A

a non polar (hydrophobic) residue such a leucine residue, a isoleucine residue or an alanine

105
Q

Why does sickling occur in deoxyhemoglobin but not in oxyhemoglobin?

A

Oxyhemoglobin has a small hydrophobic “pocket” in a Beta chain region located in the interior of the protein while deoxyhemoglobin has this hydrophobic pocket located on the surface of the protein. .

106
Q

Why does sickle cell occur in deoxyhemoglobin

A

the val interacts with the hydrophobic pocket on the surface of another HbS molecule leading to aggregation of Hbs.

107
Q

What are possible amino acids that reasonable candidates for pocket-Val 6 interactions? why?

A

This process is driven by hydrophobic interactions thus any hydrophobic amino acid is a resonable candidate.
(specific example include: leucine and phenylalanine)

108
Q

Val 6-pocket interactions result in what?

A

a string of HbS molecules that eventually form an insoluble fiber and distort the shape of the RBC into a sickle shape.

109
Q

The formation of aggregate sin HbS occurs when _____

A

[O2] falls and the deoxygenated T state begins to accumulate.

110
Q

Anemia is a possible symptoms in people with variants with _____ hemoglobin because ____

A

Anemia is a possible symptom in people with unstable hemoglobin because the RBC containing degraded hemoglobin are more likely to be destroyed.

111
Q

A person with a high-affinity variant may have ____ levels of RBC called ____

A

elevated levels of RBC called erthytocytosis or polycythemia.

112
Q

Cyanosis is a possible symptom of what?

A

The stabilization of the T state or destabilization of the R state causing hemoglobin to have a decreased affinity for oxygen.

113
Q

Hemoglobin kansas exhibits ____ cooperativity.

A

low

114
Q

Allosteric enzymes have a ____ shaped curve

A

S shaped of V0 vs. [S]

115
Q

Allosteric enzymes may have binding sites for _____ that are ____ from active sites

A

binding sites for regulatory molecules (heterotropic effectors) that are separate from enzyme’s active sites.

116
Q

Allosteric enzymes undergo _____ as a result of modulator binding.

A

conformation changes.

117
Q

If the substrate of allosteric enzymes is a substrate the effect is called a _____

A

homotropic effect.

118
Q

Allosteric enzymes have multisubunit proteins that undergo conformational shifts between a more active site and a less active site as a result of ______.Do nonallosteric enzymes show the same conformation changes ?

A

Result of modulator binding

NO nonallosteric enzymes do not show these conformation changes

119
Q

Why do allosteric enzymes have a S shape?

A

It is due to there cooperative interactions between subunits that alter the affinity of each subuit for substrate.

120
Q

What type of enzymes have a hyperbolic curve?

A

Michaelis-Menten enzymes.

121
Q

A negative modifier would do what to the graph of an allosteric enzyme?

A

Shift it to the left meaning that at a given substrate concentration there is a decrease in reaction velocity.

122
Q

What does a positive modifier do to allosteric enzymes?

A

It binds to a regulatory site on the enzyme, stabilizing the R conformation and increasing the concentration of R.

123
Q

How does a positive modifier shift the graph of allosteric enzymes?

A

Shifts it to the left thus at a given substrate concentration the reaction velocity increases; less substrate is needed to produce an equivalent amount of product.

124
Q

If substrate concentration is decreased then what will happen to [T]/[R] why?

A

[T]/[R} would increase if substrate concentration decreases; less substrate is bound so less R state enzyme is stabilized

125
Q

If a substrate concentration is increased what happens to [T]/[R]

A

[T]/[R] will decrease if substrate concentration increases; ration of [T] to [R] decreases because in positive cooperation, the binding of substrate to R state stabilizes it and enhances binding to other substrate molecules.

126
Q

What happens to hemoglobin when it binds O2 at physiological pH’s?

A

It undergoes a conformation change that makes it a slightly stronger acid. It therefore releases protons on the binding oxygen. increasing pH, that is removing protons simulates Hb to bind O2.

127
Q

~ ____ molecules of CO2 are formed per molecule of

A

0.8 molecules of CO2

128
Q

The CO2 formed per molecule of O2 is consumed by ____ from the ____ to the ____ largely as dissolved CO2 forming _______.

A

The CO2 formed per molecule is consumed by respiration diffuse from the tissues to the capillaries largely as dissolved CO2 forming bicarbonate.

129
Q

What is the reaction for bicarbonate in the body

A

CO2 + H2O —–> H+ + HCO3-

catalyzed in the erythrocytes by carbonic anhydrase.

130
Q

Most of the CO2 in the blood is carried in the form of _____

A

bicarbonate.

131
Q

In the capillaries where pO2 is ____ the H+ generated by _____ is taken up by Hb which is thereby induced to ______. This H+ uptake moreover facilitates ____ by stimulating ______.

A

In the capillaries where pO2 is low the H+ generated by bicrabonate formation is taken up by Hb where which is thereby induced to unload its bounded O2. This H+ uptake moreover facilitates CO2 transport by stimulating bicarbonate formation.

132
Q

In the lungs where pO2 is ____, O2 binding by Hb releases _____, which ______CO2.

A

In the lungs where pO2 is high, O2 binding by Hb releases the Bohr protons, which drive off the CO2.

133
Q

The reaction between the capillaries and the lungs are closely matched causing ______

A

little change in blood pH.

134
Q

Why is the mechanism of Bohr effect important to highly active muscles?

A

It supplies additional O2; Highly active muscles generate acid so fast that they lower the pH of the blood passing through them from 7.4 to 7.2. At this lowered pH Hb releases ~10% more O2 at the <20 torr pO2 in these muscles then it does at a pH of 7.4

biochemistry (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions