Hemoglobin

Question 1

What is the primary function of blood?

Answer 1

Transport and distribution system for the body, delivering essential nutrients and removing waste products.

Question 2

What are the two important proteins that interact with O2?

Answer 2

• Myoglobin (Mb) - tissue oxygen storage molecule
• Hemoglobin (Hb) - blood oxygen transport molecule

Question 3

Where is myoglobin primarily found?

Answer 3

In skeletal and striated muscle.

Question 4

What is the primary role of red blood cells?

Answer 4

To pick up oxygen in the lung and deliver it to the tissues.

Question 5

How does blood carry CO2 back to the lungs?

Answer 5

• Dissolved CO2
• Bicarbonate
• Carbaminohemoglobin

Question 6

What is hematocrit?

Answer 6

The fraction of the blood that contains RBC, typically ~40% to 50%.

Question 7

What is the normal hemoglobin concentration in blood?

Answer 7

About 15 g of hemoglobin per deciliter (dl) of blood.

Question 8

How much oxygen can each gram of hemoglobin bind?

Answer 8

1.34 ml of oxygen.

Question 9

What is the total oxygen-carrying capacity of normal blood?

Answer 9

20.1 ml of O2 per dl.

Question 10

What is the normal blood volume in men?

Answer 10

~5 to 6 liters.

Question 11

What is the normal blood volume in women?

Answer 11

~4.5 to 5.5 liters.

Question 12

What is the typical diameter of an erythrocyte disk?

Answer 12

6 to 8 μm.

Question 13

What is the thickness of a typical erythrocyte disk?

Answer 13

2 μm.

Question 14

What is the volume of a typical erythrocyte?

Answer 14

~90 fL.

Question 15

How many hemoglobin molecules does a normal red blood cell contain?

Answer 15

About 270 million.

Question 16

What is the structure of hemoglobin?

Answer 16

Tetrameric protein consisting of four subunits: two α and two β chains.

Question 17

What is myoglobin’s structural characteristic?

Answer 17

A single-chain protein that resembles one β-subunit of hemoglobin.

Question 18

What are the four structural levels of hemoglobin?

Answer 18

• Primary structure - amino acid sequence
• Secondary structure - alpha-helical folding
• Tertiary structure - 3D shape of globin subunit
• Quaternary structure - arrangement of four subunits

Question 19

What is the Tense (T) State of hemoglobin?

Answer 19

The low-affinity state where hemoglobin has a lower tendency to bind oxygen.

Question 20

What is the Relaxed (R) State of hemoglobin?

Answer 20

The state where binding of oxygen increases hemoglobin’s affinity for more oxygen.

Question 21

What does the transition from T to R state explain?

Answer 21

Hemoglobin’s cooperative binding.

Question 22

What happens to Fe²⁺ when oxygen binds in hemoglobin?

Answer 22

Fe²⁺ moves into the plane of the porphyrin ring, shifting the protein structure.

Question 23

What shape does the oxygen binding curve for myoglobin take?

Answer 23

Hyperbolic.

Question 24

What shape does the oxygen binding curve for hemoglobin take?

Answer 24

Sigmoidal (S-shaped).

Question 25

What is the Bohr effect?

Answer 25

Influence of pH and CO₂ levels on oxygen binding.

Question 26

What effect does 2,3-BPG have on hemoglobin?

Answer 26

Reduces hemoglobin's oxygen affinity, promoting oxygen release.

Question 27

What is the normal effect of smoking on 2,3-BPG levels?

Answer 27

2,3-BPG is overproduced.

Question 28

What is carboxyhemoglobin?

Answer 28

A complex formed when carbon monoxide binds to hemoglobin.

Question 29

How does fetal hemoglobin compare to adult hemoglobin in terms of oxygen binding?

Answer 29

Fetal hemoglobin binds O2 more tightly than adult hemoglobin.

Question 30

What are hemoglobinopathies?

Answer 30

Genetic defects that produce an abnormal structure of globin chains.

Question 31

What mutation causes sickle cell anemia?

Answer 31

Replacement of glutamic acid with valine at position 6 of the β-globin chain.

Question 32

What is porphyria?

Answer 32

A disorder where the body can’t make enough heme, leading to a buildup of harmful porphyrins.

Question 33

What leads to microcytic anemia?

Answer 33

Iron deficiency causing red blood cells to become smaller and paler.

Question 34

What is methemoglobinemia?

Answer 34

A disorder where hemoglobin cannot release oxygen properly to body tissues.

Question 35

What state does iron exist in methemoglobin?

Answer 35

Fe³⁺ (ferric) state.

Question 36

What are the symptoms of methemoglobinemia?

Answer 36

* Cyanosis (bluish skin) * Shortness of breath