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Chemistry Fall 24' > Chem 20 Nov Lecture > Flashcards

Chem 20 Nov Lecture Flashcards

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1
Q

What is the primary function of myoglobin?

A

Storage of oxygen in muscle tissue

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2
Q

What is the primary function of hemoglobin?

A

Transport of oxygen from lungs to tissues and carbon dioxide from tissues to lungs

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3
Q

What structural feature is central to the function of heme proteins?

A

Porphyrin complex with a coordinated iron ion

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4
Q

What is the significance of the Bohr effect?

A

Explains how pH and temperature affect oxygen binding

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5
Q

How does fetal hemoglobin differ from adult hemoglobin in terms of oxygen affinity?

A

Fetal hemoglobin has a higher affinity for oxygen

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6
Q

What is the role of 2,3-bisphosphoglycerate (BPG) in hemoglobin function?

A

It binds to adult hemoglobin and decreases its oxygen affinity

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7
Q

What is cooperative binding?

A

Binding at one site increases binding at additional sites within the protein structure

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8
Q

What is the Hill coefficient and what does it indicate?

A

A mathematical tool to quantify cooperative binding; greater than 1 indicates cooperative binding

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9
Q

What is the relationship between myoglobin and hemoglobin regarding their affinity for oxygen?

A

Myoglobin has a higher affinity for oxygen than hemoglobin

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10
Q

Fill in the blank: Hemoglobin is a _______ protein, while myoglobin is a _______ protein.

A

tetrameric; monomeric

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11
Q

True or False: Myoglobin participates in cooperative binding.

A

False

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12
Q

What physiological conditions can affect the ability of oxygen to bind to hemoglobin?

A

Temperature, pH, and CO2 levels

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13
Q

What is the significance of the sigmoidal curve in the oxygen binding graph of hemoglobin?

A

Indicates cooperative binding

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14
Q

What are the two main effects discussed in relation to oxygen and carbon dioxide binding?

A

Bohr effect and Haldane effect

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15
Q

What is carbaminohemoglobin?

A

Hemoglobin bound to carbon dioxide

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16
Q

How does carbon monoxide affect oxygen transport?

A

It competes with oxygen for binding to heme, reducing oxygen transport

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17
Q

What is the role of the carbonate buffering system?

A

Transporting carbon dioxide in the blood and maintaining pH balance

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18
Q

What happens to myoglobin’s oxygen release during exercise?

A

Releases oxygen as tissue oxygen levels decrease

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19
Q

What is the impact of chloride ions on the carbonate buffering system?

A

They help maintain balance in transporting carbon dioxide

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20
Q

What type of binding does cyanide exhibit with heme proteins?

A

Competitive binding

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21
Q

What is the difference in binding site availability between myoglobin and hemoglobin?

A

Myoglobin has one binding site; hemoglobin has four

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22
Q

What is the Hill coefficient of myoglobin?

A

1

Myoglobin has a Hill coefficient of one, indicating non-cooperative binding.

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23
Q

What is the Hill coefficient of globin?

A

2.7

The Hill coefficient of globin suggests cooperative binding.

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24
Q

What does cooperative binding in hemoglobin indicate?

A

Increased oxygen affinity as more oxygen binds

Cooperative binding allows each subsequent heme group to bind oxygen more easily.

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25
Q

What happens to oxygen affinity as more oxygen is bound to hemoglobin?

A

It increases

The affinity for oxygen rises from one to four bound oxygens.

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26
Q

What are the two states of hemoglobin?

A

T state (tense) and R state (relaxed)

T state is rigid, while R state is more flexible and allows for better binding.

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27
Q

What structural change occurs in hemoglobin when oxygen binds?

A

A shift in protein structure

This shift increases the affinity for additional oxygen binding sites.

28
Q

What is the difference between fetal hemoglobin and adult hemoglobin in terms of oxygen affinity?

A

Fetal hemoglobin has a higher affinity for oxygen

This difference is partly due to the presence of gamma domains instead of beta domains in fetal hemoglobin.

29
Q

What role does 2,3-bisphosphoglycerate (BPG) play in hemoglobin?

A

It binds to adult hemoglobin and decreases oxygen affinity

BPG stabilizes the T state of hemoglobin, reducing its ability to bind oxygen.

30
Q

How does BPG interact differently with fetal hemoglobin compared to adult hemoglobin?

A

BPG binds weakly to fetal hemoglobin

This weak binding allows fetal hemoglobin to maintain a higher affinity for oxygen.

31
Q

What happens to hemoglobin’s affinity for oxygen when BPG is bound?

A

It decreases

BPG binding shifts the equilibrium towards the T state, lowering oxygen affinity.

32
Q

What is the significance of the leftward shift in the dissociation curve for fetal hemoglobin?

A

Indicates increased affinity for oxygen

A leftward shift means that fetal hemoglobin can bind oxygen more effectively than adult hemoglobin.

33
Q

What type of interaction does BPG have with the histidine residues in adult hemoglobin?

A

Ion-ion interactions

These interactions are strong due to the positive charge of histidine and the negative charge of BPG.

34
Q

What amino acid replaces histidine in fetal hemoglobin, and how does this affect BPG binding?

A

Serine replaces histidine, reducing BPG binding

The smaller size and lack of charge in serine lead to weaker interactions with BPG.

35
Q

When hemoglobin is in the R state, what is its binding capability?

A

It has a higher binding affinity for oxygen

The R state allows for more effective oxygen binding due to structural changes.

36
Q

Fill in the blank: The T state of hemoglobin is also known as the _______.

A

tense state

37
Q

True or False: BPG binding increases the binding affinity of oxygen to hemoglobin.

A

False

BPG binding decreases oxygen affinity by stabilizing the T state.

38
Q

What happens to hemoglobin affinity when BPG binds?

A

It shifts the curve to the right, lowering oxygen affinity.

BPG (2,3-bisphosphoglycerate) stabilizes the T state of hemoglobin, making it less likely to bind oxygen.

39
Q

How does fetal hemoglobin differ from adult hemoglobin in terms of BPG binding?

A

Fetal hemoglobin has a higher affinity for oxygen and does not bind BPG effectively.

This allows fetal hemoglobin to absorb oxygen more readily from maternal blood.

40
Q

What is the role of BPG in hemoglobin function?

A

BPG stabilizes the T structure of hemoglobin, preventing conformational changes necessary for higher oxygen affinity.

This rigidity affects the ability of hemoglobin to release oxygen.

41
Q

True or False: Binding of oxygen to hemoglobin increases the affinity for BPG.

A

False.

Binding oxygen causes conformational changes that can displace BPG.

42
Q

What is the primary way carbon dioxide is transported in the blood?

A

As bicarbonate, through the blood buffering system.

About 70% of CO2 is converted to bicarbonate, with 10% dissolved in plasma and 20% bound to hemoglobin.

43
Q

What is carbaminohemoglobin?

A

Hemoglobin that has CO2 bound to its N-terminal groups, forming carbamate.

This binding lowers hemoglobin’s affinity for oxygen.

44
Q

What effect does increased temperature have on oxygen dissociation?

A

Increased temperature causes oxygen to dissociate more rapidly.

Higher temperatures promote oxygen release, which is crucial during metabolic activity.

45
Q

Fill in the blank: The Bohr effect describes how increased _______ lowers the affinity of hemoglobin for oxygen.

A

CO2 levels.

Increased CO2 leads to lower pH, affecting hemoglobin’s structure and function.

46
Q

What happens to hemoglobin affinity for oxygen when pH decreases?

A

The affinity for oxygen decreases.

This is due to protonation of amino acid residues, affecting conformational changes.

47
Q

What is the relationship between the Haldane effect and carbon dioxide affinity?

A

The Haldane effect states that decreased oxygen affinity increases carbon dioxide affinity.

This reflects the competitive binding interactions between oxygen and carbon dioxide.

48
Q

True or False: A decrease in temperature increases the ability of hemoglobin to release oxygen.

A

False.

Lower temperatures decrease the dissociation of oxygen, making it harder for tissues to receive oxygen.

49
Q

What does the term ‘cooperative binding’ refer to in the context of hemoglobin?

A

The phenomenon where binding of one oxygen molecule increases the affinity for subsequent oxygen molecules.

This characteristic is crucial for efficient oxygen uptake and release.

50
Q

How does BPG affect the T state and R state of hemoglobin?

A

BPG favors the T state, which is the deoxygenated form, over the R state, which is oxygenated.

This shift is essential for the release of oxygen in tissues.

51
Q

What is the primary difference between affinity and dissociation in the context of binding?

A

Affinity looks at the desire to bind, while dissociation looks at the desire to release.

52
Q

How does temperature affect the release of oxygen?

A

Increasing temperature increases the ability to release oxygen; decreasing temperature decreases it.

53
Q

Which gas has a higher affinity for heme than oxygen?

A

Carbon monoxide (CO).

54
Q

Why is carbon monoxide considered toxic?

A

It binds to heme with a higher affinity than oxygen and does not release it, interrupting oxygen exchange.

55
Q

What happens to oxygen transport when carbon monoxide binds to heme?

A

It prevents oxygen from binding due to competitive binding at the same site.

56
Q

What is the role of carbon dioxide (CO2) when binding to hemoglobin?

A

CO2 binds at a different site and allows conformational shifts to occur for oxygen binding.

57
Q

What can be done to overcome carbon monoxide binding to hemoglobin?

A

Increase oxygen saturation levels to kick out CO and allow O2 to bind.

58
Q

Does myoglobin have a similar binding issue with carbon monoxide as hemoglobin?

A

Not significantly, as myoglobin is stored in muscles and has a strong affinity for oxygen.

59
Q

What prevents carbon monoxide from binding to myoglobin when oxygen is already bound?

A

If oxygen is bound, CO cannot bind unless CO levels are extremely high.

60
Q

Where does carbamate bind in the hemoglobin structure?

A

To the N terminus of the protein, not to the heme portion.

61
Q

What is the Haldane effect?

A

It describes how CO2 affects the dissociation of oxygen in the blood.

62
Q

What is the Hamburger phenomenon?

A

It deals with chloride movement in the carbonate buffering system during CO2 exchange.

63
Q

How many ways can carbon dioxide be transported in the body?

A

Three ways.

64
Q

What happens to CO2 when it enters the blood?

A

It converts to bicarbonate and is transported back to the lungs.

65
Q

What occurs when bicarbonate reaches the lungs?

A

It converts back to CO2, which then crosses the lung membrane.

Chemistry Fall 24' (8 decks)

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