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Chemistry Fall 24' > Chem 19 Nov Lecture > Flashcards

Chem 19 Nov Lecture Flashcards

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1
Q

What are the main functions of hemoglobin?

A

Transports oxygen from the lungs to tissues

Hemoglobin also picks up carbon dioxide from tissues to return to the lungs.

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2
Q

What is the primary function of myoglobin?

A

Stores and transports oxygen within muscle tissue

Myoglobin is essential for metabolic pathways like ATP production.

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3
Q

What is the structure of myoglobin?

A

Monomeric heme protein with one APO protein and one heme complex

Myoglobin’s structure allows it to efficiently store oxygen.

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4
Q

How does hemoglobin differ from myoglobin in terms of structure?

A

Hemoglobin is a tetramer with four subunits, each with a heme complex

This quaternary structure allows hemoglobin to transport oxygen more effectively.

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5
Q

What is the role of iron in heme proteins?

A

Binds oxygen in the ferrous state (Fe2+)

Iron forms an octahedral complex with six ligands in heme proteins.

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6
Q

What is the coordination geometry of iron in heme proteins?

A

Octahedral complex

Six coordination sites are formed by the heme group.

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7
Q

What is the porphyrin system?

A

A series of heterocyclic rings that form the heme group

Porphyrins are highly conjugated and essential for biological functions.

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8
Q

What are the components required for heme synthesis?

A

Glycine and succinyl-CoA

These components form protoporphyrin IX, which is then coordinated with iron.

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9
Q

What enzyme coordinates iron into the porphyrin ring during heme synthesis?

A

Ferrochelatase

This enzyme completes the heme complex.

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10
Q

What happens to the structure of hemoglobin upon oxygen binding?

A

Iron moves to a more planar position

This change increases hemoglobin’s affinity for additional ligands.

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11
Q

True or False: Myoglobin has a higher affinity for oxygen than hemoglobin.

A

True

Myoglobin’s higher affinity allows it to effectively store oxygen in muscle tissue.

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12
Q

What is the effect of carbon monoxide on hemoglobin?

A

Binds to heme complex, better than O2

This can lead to carbon monoxide poisoning due to competitive binding.

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13
Q

Fill in the blank: Myoglobin is found in __________ tissue.

A

[muscle]

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14
Q

What is the significance of fetal hemoglobin?

A

Has a higher affinity for oxygen than adult hemoglobin

This is crucial for oxygen transport from mother to fetus.

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15
Q

What biochemical process does myoglobin assist with besides oxygen storage?

A

Oxidizing nitric oxide into nitrate

This process enhances cellular respiration.

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16
Q

What type of spectroscopy can measure differences between deoxy and oxyhemoglobin?

A

Absorption spectroscopy

This technique is essential for devices like pulse oximeters.

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17
Q

What happens to myoglobin’s oxygen binding ability as oxygen levels fluctuate?

A

Releases or binds oxygen based on concentration

Myoglobin adjusts its oxygen storage to meet metabolic demands.

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18
Q

What is the primary function of hemoglobin?

A

Delivery of oxygen to tissues.

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19
Q

What is the ferrous state of iron?

A

Iron in the +2 state, which actively binds oxygen.

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20
Q

What type of bonds do ligands form with metals?

A

Coordination bonds.

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21
Q

What is the role of ligands in coordination with metals?

A

Ligands stabilize the charge on the metal and help solubilize it.

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22
Q

What types of species can act as ligands?

A

Simple non-metals (like chlorides) or polyatomic ions.

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23
Q

What is hybridization in the context of bonding?

A

The mixing of atomic orbitals to create new hybrid orbitals.

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24
Q

What hybridization occurs in carbon to explain its four bonds?

A

sp3 hybridization.

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25
Q

What types of bonds do s and p orbitals form?

A
  • S orbitals form sigma bonds * P orbitals form pi bonds.
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26
Q

How does iron hybridize when forming coordination complexes?

A

Iron hybridizes into sp3d2 orbitals.

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27
Q

What is the electron configuration of iron?

A

Argon, 4s², 3d⁶.

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28
Q

What structure do iron complexes typically form?

A

Octahedral complex.

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29
Q

What is the coordination number of iron in an octahedral complex?

A

Six.

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30
Q

True or False: Ligands donate electron density to stabilize the metal’s charge.

A

True.

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31
Q

What happens to the d electrons during the hybridization of iron?

A

The d electrons remain in the d orbitals while hybridizing s and p orbitals.

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32
Q

Fill in the blank: The active state of iron that binds oxygen is known as the _______.

A

ferrous state.

33
Q

What is the typical coordination geometry of a metal complex with six ligands?

A

Octahedral.

34
Q

What keeps the metal-ligand bond from being a full covalent bond?

A

The interaction is more akin to a coordination bond where electron density is donated.

35
Q

What is the importance of having empty orbitals in transition metals?

A

Empty orbitals are required to accept electron density from ligands.

36
Q

What are the two types of tornado groups mentioned?

A

Equatorial and axial (E and F) tornado groups

37
Q

What is the role of iron in the heme complex?

A

Iron is where oxygen binds

38
Q

What is ligand E in the heme complex?

A

Oxygen, which typically sits above the iron

39
Q

What must happen for iron to effectively bind oxygen?

A

Other components are needed due to solubility issues

40
Q

What is a porphyrin?

A

A series of heterocyclic rings tied together, forming a macrocycle

41
Q

What defines a macrocyclic structure?

A

Contains more than 10 atoms

42
Q

How many pyrrole rings are in a porphyrin?

A

Four pyrrole rings

43
Q

What is conjugation in organic compounds?

A

The overlapping of p orbitals that allows electrons to move freely

44
Q

True or False: Conjugation is important for biological functions.

A

True

45
Q

What enzyme in the eye is related to the concept of conjugation?

A

Merdopsin

46
Q

What is the significance of conjugation in vision?

A

It allows electrons to travel and release a protein essential for vision

47
Q

What is aromaticity based on?

A

The concept of conjugation

48
Q

Where can porphyrin systems be found besides humans?

A

In plants (chlorophyll) and bacteria

49
Q

What is the porphyrin in hemoglobin and myoglobin called?

A

Protoporphyrin IX

50
Q

What is required to synthesize heme from protoporphyrin?

A

Iron must coordinate with the porphyrin

51
Q

What type of enzyme is ferrochelatase?

A

An enzyme that coordinates iron into the porphyrin

52
Q

What is an APO protein?

A

An unbound protein that is inactive

53
Q

How does a protein become functional in relation to heme?

A

It coordinates with heme to increase solubility and functionality

54
Q

What makes heme hydrophobic?

A

The electron density donated to iron by the coordinated nitrogens

55
Q

What type of reactions are involved in heme synthesis?

A

Substitution, elimination, and redox reactions

56
Q

Fill in the blank: Conjugation allows for _______ movement of electrons.

A

free

57
Q

What happens to heme when it coordinates with a protein?

A

It becomes soluble and functional

58
Q

How many coordination sites does iron have in the heme complex?

A

Six coordination sites

59
Q

What is the role of the histidine residue in the heme complex?

A

The histidine residue binds to the iron, acting as the fifth ligand

60
Q

What are the two types of protein structures compared in myoglobin and hemoglobin?

A

Myoglobin is a monomeric heme protein (tertiary structure), while hemoglobin is a tetramer (quaternary structure)

61
Q

What is the difference between adult hemoglobin and fetal hemoglobin?

A

Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin

62
Q

True or False: Hemoglobin has four subunits.

A

True

63
Q

Fill in the blank: Myoglobin has a ______ structure.

A

tertiary

64
Q

What happens to the iron position in the heme complex when oxygen binds?

A

The iron is pulled back up into a more planar position

65
Q

What is the difference in binding affinity between carbon monoxide and oxygen?

A

Carbon monoxide is a better binder than oxygen

66
Q

What is the significance of measuring the absorbance of deoxyhemoglobin versus oxyhemoglobin?

A

It allows determination of the relative amounts of oxyhemoglobin and deoxyhemoglobin

67
Q

What type of spectroscopy is used to measure differences in hemoglobin states?

A

Absorbance spectroscopy

68
Q

What does the presence of multiple peaks in the absorbance spectrum indicate?

A

The presence of oxyhemoglobin

69
Q

Fill in the blank: Hemoglobin contains two ______ subunits and two ______ subunits in its adult form.

A

alpha; beta

70
Q

What can affect the ability of heme to bind oxygen?

A

Environmental factors such as pH and salt concentration

71
Q

What happens to the affinity of hemoglobin for oxygen after the first oxygen is bound?

A

The affinity for the remaining heme groups increases

72
Q

What is the structural characteristic of myoglobin that differentiates it from hemoglobin?

A

Myoglobin consists of a single heme group

73
Q

Fill in the blank: The histidine that binds to the iron is known as ______.

A

histidine eight

74
Q

What is the consequence of a histidine being too far away from the iron in the heme complex?

A

It cannot form an interaction with the iron

75
Q

What happens to fetal hemoglobin production after six months of age?

A

It begins to diminish

76
Q

What is the primary function of hemoglobin?

A

Transport oxygen from the lungs to tissues

77
Q

True or False: The heme complex can bind cyanide.

A

True

78
Q

How does the presence of oxygen change the heme structure?

A

It alters the heme structure to allow all six binding sites to be occupied

79
Q

What type of model is used to represent myoglobin in structural biology?

A

Tertiary structure model

Chemistry Fall 24' (8 decks)

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