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Hematological Genetics > Hemoglobin > Flashcards

Hemoglobin Flashcards

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Biology 101 flashcards
1
Q

How many red blood cells are produced per second?

A

2.4 million RBC/s

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2
Q

How long do red blood cells last?

A

120 days

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3
Q

What is the function of erythrocytes?

A

To transport oxygen from the lungs to the tissue.

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4
Q

How man liters of O₂ per day do human red blood cells carry?

A

500-1,000 liters

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5
Q

What percent volume of the erythrocyte does hemoglobin occupy?

A

33%

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6
Q

What percent of hemoglobin is synthesized before extrusion of the nucleus?

A

65%

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7
Q

Reticulocytes make what remaining percent of Hb?

A

35%

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8
Q

What percent of protein synthesis in reticulocytes is globin synthesis?

A

95%

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9
Q

Explain the stages of erythropoiesis, what happens at each phase, and what cell types are present?

A

Stem cell: (Hemocytoblast)
Commited cell: (Proerythroblast)
Phase 1: “ribosome synthesis” (Early erythroblast, Late erythroblast)
Phase 2: “Hb accumulation” (Late erythroblast, Normoblast)
Phase 3: “nucleus ejection” (Normoblast, Reticulocyte)
: Erythrocyte

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10
Q

What part of the body makes red blood cells at each point of development?

A

0-8 wks: Yolk sac
1 mos-birth: Liver
2 mos-birth+2 mos: Spleen
7 mos+: Bone marrow

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11
Q

What are the hemoglobin levels by age and sex?

A

Adult male: 14-18 g/dL
Adult female: 12-16 g/dL
Newborn: 111-16 g/dL
Child: 12-15 g/dL

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12
Q

What is the subunit protein structure of hemoglobin?

A

Tetramer

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13
Q

What is the globin stuctrue of hemoglobin?

A

2 ∝-globin chains

2 β-globin chains

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14
Q

How many heme per subunit and what is the charge of the iron atom?

A

1 heme per subunit

ferrous iron, Fe²⁺

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15
Q

What kind and how many rings are in the hemoglobin structure?

A

4 protoporphyrin IX rings

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16
Q

What are the types of globin chains in a normal adult?

A

∝ (alpha)
β (beta)
𝛿 (delta)
γ (gamma)

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17
Q

What is the length of the globin chains?

A

∝ globin= 141 amino acids

all others= 146 amino acids

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18
Q

Which chains are ∝-like?

A

ζ (zeta)

∝ (alpha)

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19
Q

Which chains are β-like?

A

ε (epsilon)
γ (gamma)
𝛿 (delta)
β (beta)

20
Q

What are the globin genes?

A

HBA1, HBA2, HBB

21
Q

What are the homoglobin names?

A

HbA, HbS, HbSC, HbF, Gower, Portland

22
Q

Where are the globin genes located?

A

β globin genes= Chromosome 11

∝ globin genes= Chromosome 16

23
Q

When is embryonic hemoglobin expressed and where is it made?

A

Yolk sac from 0-8 wks

24
Q

When is fetal hemoglobin primarily expressed and where is it predominately made?

A

Liver & bone marrow from 34-36 wks

25
Q

What does hemoglobin switching depend on?

A

Gestational age (time of fertilization)

26
Q

What percentage of each hemoglobin type is present in a normal adult?

A

HbA: 97%
HbA2: 3%
HbF: 0.5%

27
Q

What are the different types of hemoglobin and what globin chains are they made of?

A 
Adult:
*HbA (∝2β2)
*HbA2 (∝2𝛿2)
Fetal:
*HbF (∝2γ2)
Embryonic:
*Hb Gower 1 (ζ2ε2)
*Hb Gower 2 (∝2ε2)
*Hb Portland (ε2γ2)
Sickle cell:
*HbS
28
Q

What substitution occurs to cause sickle cell anemia and at what position does it occur?

A

An amino acid at position #6 in β globin substitutes valine for glutamic acid.

29
Q

What causes the sickle shape shape in sickle cell anemia?

A

Polymerization of hemoglobin forming rods?

30
Q

What are symptoms associated with sickle cell anemia?

A

Impeded circulation, hemolytic anemia, pain, organ damage strokes increased infections

31
Q

What is a treatment for sickle cell anemia and what is the drawback?

A

Treatment with hydroxyurea to induce HbF & address inflammation. It is a chemotherapeutic agent.that can cause cancer.

32
Q

In what order are globin genes arranged on the chromosome?

A

Linearly 5’ to 3’ in the same order of activation as expression.

33
Q

What is the prosthetic group of hemoglobin?

A

Heme, a non-amino acid group

34
Q

What is the organic component of heme and how many pyrole rings does it have?

A

Protoporphyrin

4 pyrole rings

35
Q

How are amino acids labeled in hemoglobin?

A

Names according to helical segment & # amino acid in that segment e.g. F8 & E7

36
Q

Which amino acid is bound to the heme group?

A

F8 the proximal histidine

37
Q

Which amino acid is bound to the iron that O₂ binds to along with heme?

A

E7 the distal histidine

38
Q

What stabilizes O₂ binding to iron?

A

E7 forming a H-bond with O₂

39
Q

What occurs after O₂ binds iron?

A

A 0.4 Å shift pulls the rest of the globin chain pulling the F8 histidine

40
Q

What is the structure of myoglobin?

A

Monomer

41
Q

Where and at what pressure does hemoglobin pick up O₂ and where and at what pressure does hemoglobin drop off O₂?

A

Picks up O₂ in the lungs @ 100 mm Hg and drops it off to myoglobin in the tissues @ 10-20 mm Hg

42
Q

What does it mean that O₂ binds cooperatively and what kind of curve represents this?

A

1 O₂ binding causes conformational ∆ in ∝-helix which ↑ affinity to bind more O₂. Represented by sigmoidal curve

43
Q

What modulates Hb function and how does it change O₂ affinity?

A

↑ 2,3-BPG= ↑T form= ↓ O₂ affinity
↓ pH= ↓O₂ affinity
R form= ↑O₂ affinity

44
Q

What is the sequential model?

A

Hb binds/releases O₂ sequentially

45
Q

What is the concerted model?

A

Hb binds/releases O₂ all at once

46
Q

What is carboxyhemoglobin and how strongly does it bond O₂?

A

CO+heme→carboxyhemoglobin, CO bond= 210* O₂ bond

47
Q

What is HbA1c? What is its normal level and diabetic level?

A

β-globin+glucose→ HbA1c= irreversible.

Normal level= 3%= 2-3 in diabetics

Hematological Genetics (8 decks)

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