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Molecules and Cells Unit 1A > Hemoglobin > Flashcards

Hemoglobin Flashcards

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Organic Chemistry 101 flashcards
1
Q

What two blood proteins constitute 95% of blood iron?

A

Hemoglobin and ferritin

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2
Q

List the flow of 02 from the atmosphere and its final form within the body.

A

bronchi–>lungs–>hemoglobin–>(myoglobin)–>mitochondria–> water

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3
Q

The total oxygen content consists of what two types of oxygen?

A

O2 on Hb (SaO2) + dissolved O2 (PO2)

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4
Q

A pale hemoglobin hue may be indicative of :

A

Anemia

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5
Q

A blueish hemoglobin hue may be indicative of :

A

Cyanosis

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6
Q

A yellowish hemoglobin hue may be indicative of :

A

High [bilirubin] –> jaundice

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7
Q

A cherry red hemoglobin hue may be indicative of :

A

Carbon monoxide poisoning

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8
Q

A brownish/blue hemoglobin hue may be indicative of :

A

Metheglobinemia (chocolate cyanosis).

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9
Q

Oxidizing drugs cause the conversion of hemoglobin to metheglobin via what enzyme?

A

Met-Hb oxidase

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10
Q

Lysis of non-functional met-Hb leads to the what changes in blood contents?

A

An increase in reticulocytes and bilirubin (leading to jaundice) and a decrease in hematocrit.

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11
Q

Where does heme/Hb synthesis occur?

A

Differentiating bone marrow cells

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12
Q

What are the normal hematocrit percentages for males vs females?

A

females: 36-46%
males: 41-53%

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13
Q

What is the bodies response to hypoxic renal conditions?

A

1) release of HIF-1 (Hypoxia inducible factors)
2) Increased release of EPO (erythropoietin)
3) Increase production of RBCs

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14
Q

What occurs after aged red blood cells are taken up by the spleen.

A

Degradation by macrophages and conversion of the biproduct (bilirubin) is converted to Bilirubin di-glucuronide (hydrophobic) to allow release into bile.

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15
Q

What are the components of the hemoglobin holoprotein?

A

Heme: 4 protoporphyrin IX rings + Fe2+
Globin: 2 alpha and 2 beta chains

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16
Q

What are the 6 possible covalent binding sites on the heme structure?

A

4 Nitrogen atoms + a proximal and distal histidine

17
Q

In the carbomonoxy-Hb form, what may be bound to the 6th position of heme?

A

CO (Carbon monoxide)

18
Q

In the Met-Hb form, what may be bound to the 6th position of heme?

A

CN- (Cyanide); H20; Cl-

19
Q

In the Cyano Met-Hb form, what may be bound to the 6th position of heme? What is the purpose of this form?

A

CN-; Met-Hb traps cyanide, marking it for lysis and expulsion by the spleen into bile.

20
Q

What are the allosteric effectors of hemoglobin?

A

H+
CO2
2,3-BPG
Cl-

21
Q

Name the 3 main forms of adult hemoglobin and their concentrations (%) in the present.

A

HBA1 - alpha-2, beta-2 -96.8%
HBA2 - alpha-2, delta-2 -2.70%
HBF - alpha-2, gamma-2 -0.47%

22
Q

What is the functional definition of p50?

A

The [O2] required for 50% saturation of Hb (measure of O2 affinity).

23
Q

The Hill Equation

A

Y = PO2^nh / (P50^nh) + (PO2^nh)

24
Q

What does the Hill coefficient measure?

A

degree of cooperative interaction between oxygen binding sites.

25
Q

What are the only 2 charged residues in the interior of normal adult hemoglobin?

A

His E-7 and F-8

26
Q

When oxygen binds to hemoglobin this leads to a global change. What product is formed and what molecule changes position within the structure?

A

Oxyhemoglobin; Fe2+

27
Q

In the MWC model, which conformation state is favored per each cooperative binding state?

A

Oxygen bound: R state favored

Deoxygenated: T state favored

28
Q

How is hemoglobin’s high affinity for oxygen when in the R state (O2 bound) overcome?

A

2,3-BPG stabilizes the T state and lowers affinity

29
Q

When 2,3-DPG is high, what has to occur in order for transition from the T to R state?

A

High amounts of O2 must be present

30
Q

How does 2,3-BPG affect HbF? Why?

A

It has much lesser affect, allowing maternal HbA O2 to be released and passed to HbF; HbF is missing a His-143 on the gamma subunit

31
Q

How is deoxyHb T structure stabilized due to high [H+] in the Bohr Effect ?

A

3 amino acids form 2 salt bridges (require a proton-bound His-146 residue).

32
Q

Where does protonation occur as a result of the Bohr Effect?

A

His-146; His-122; amino termini ***on alpha chains

33
Q

How does CO2 lower the affinity of hemoglobin for oxygen? What is this called?

A

Stabilizes deoxyHb by binding amino terminals and forming carbamates (also by causing a pH drop).

It is called the Haldane Effect

34
Q

How does chloride promote the formation of the T-state/DeoxyHb?

A

via interaction with positive deoxyHb side-chains, stabilizing ionic interactions.

35
Q

CO2 bound hemoglobin causes remaining open sites to shift to the _______.

A

right (O2 affinity decreases)

Molecules and Cells Unit 1A (11 decks)

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