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Biology > Haemoglobin A1 > Flashcards

Haemoglobin A1 Flashcards

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1
Q

Oxygen combines with haemoglobin to form what?
-talk about saturation of haemoglobin too

A
  1. oxyhaemoglobin
  2. haemoglobin will not always form with 4 oxygen molecules
  3. sometimes it will uptake less eg. 2 therefore it will be less saturated
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2
Q

Describe the structure of haemoglobin. (4)

A
  1. a protein molecule
  2. with a quaternary structure
  3. composed of four subunits (combines to 4 oxygen molecules)
  4. each containing a haem group (each combines with one oxygen molecule)
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3
Q

Define the following…
- partial pressure
- loading
- unloading
- affinity

A
  1. partial pressure - the amount of a particular gas in a mixture of gases or solution
  2. when oxygen is taken up by haemoglobin (association)
  3. when oxygen is released/given up by haemoglobin (dissociation)
  4. a natural attraction to something eg. HB loads oxygen because it has a high affinity to it
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4
Q

How does loading and unloading of oxygen relate to surrounding O2 concentration? (3)

A
  1. more oxygen loaded in an area of high concentration O2 than low
  2. more oxygen unloaded in an area of low concentration of O2
  3. due to concentration gradients
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5
Q

What is the partial pressure like in the lungs compared to in the tissues and why?

A
  1. partial pressure in lungs is high - p.p. of O2 is high in capillaries, HB has a high affinity for O2 at high p.p. Haemoglobin becomes fully saturated as red blood cells pass through pulmonary capillaries. The HB has bound its max amount of oxygen and is 98%+ saturated.
  2. partial pressure low in tissues - p.p. of O2 in tissue capillaries is only about 5kPa. HB has a low affinity for O2 at a low p.p. of O2 and so the oxyhaemoglobin starts to break down and release oxygen.
  3. the oxygen released is then available to the tissue cells to be used in respiration.
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6
Q

What is a sigmoid curve and what does it represent for haemoglobin?

A
  1. an S shaped curve
  2. starts slow and then begins to increase faster
  3. shows that when the first couple O2 moles attach to haemoglobin, more being to do so quicker
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7
Q

Describe the effects of increased respiration on oxygen dissociation. (4 marks)

A
  1. tissue cells respire quickly
  2. respiration uses the O2 surrounding the tissue
  3. this reduces the O2 to a level lower than normal
  4. haemoglobin will become more dissociated (less saturated) and more oxygen will be released from the haemoglobin to the tissue cells.
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8
Q

Describe and explain the Bohr effect and shift.
What are the benefits?
(4 marks)

A
  1. in high concentrations of CO2, haemoglobins affinity for O2 is lowered
  2. if CO2 levels increase, saturation of O2 decreases
  3. this causes the haemoglobin oxygen dissociation curve to shift to the right (Bohr shift)
  4. can only use the term shift if both lines are for the same organism
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9
Q

Why does haemoglobin have a lower affinity to oxygen at high concentrations of CO2?

A
  1. when CO2 dissolves, it makes the blood acidic
  2. this lowers the PH
  3. as haemoglobin is a protein, change in the PH alters its tertiary structure
  4. therefore cannot carry out function as well.
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10
Q

Why does more respiration give body tissues more oxygen?
(3 marks)

A
  1. more respiration = more CO2
  2. more CO2 = HB lower affinity to oxygen
  3. therefore extra oxygen unloaded and available for respiring cells.
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11
Q

Heat from respiration helps mammals to maintain a constant body temperature. Use the information to explain the relationship between the surface area to volume ratio of mammals and the oxygen dissociation curves of their haemoglobins.
(5)

A
  1. smaller mammal has greater surface area to volume ratio
  2. smaller mammals/larger SA : volume ratio, has greater rate of respiration/metabolism
  3. oxygen required for respiration - haemoglobin releases more oxygen / haemoglobin has lower affinity.
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12
Q

Explain the process of aerobic respiration for the Bohr shift.

A
  1. increase in partial pressure of CO2 in blood
  2. oxygen dissociation curve shifts to right
  3. haemoglobin has a lower affinity to oxygen
  4. more O2 is unloaded (dissociates) at the tissue for use in aerobic respiration.
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13
Q

Explain the process of aerobic respiration for small mammals and birds.

A
  1. large SA : volume ratio
  2. therefore lose heat readily to the environment
  3. must increase rate of respiration to maintain body temperature
  4. haemoglobin has a lower affinity for oxygen
  5. more O2 is unloaded (dissociated) at the tissue
  6. for use in aerobic respiration
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14
Q

Describe how haemoglobin normally loads oxygen in the lungs and unloads it in a tissue cell.
(9 marks )

A
  1. oxygen combines (reversibly) to produce oxyhaemoglobin
  2. each haemoglobin molecule/one haemoglobin may transport 4 molecules of oxygen
  3. high partial pressure/concentration of oxygen in lungs
  4. haemoglobin is 95/100% saturated
  5. unloads at low oxygen tension in tissues
  6. presence of CO2 displaces curve further to right / increases oxygen dissociation
  7. allows more O2 to be unloaded
  8. increase temp/acidity allows ore O2 to be unloaded
  9. low p.p. O2 / increase CO2 / increased acid occurs in vicinity of respiring tissue.
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15
Q

Explain how oxygen in a red blood cell is made available for respiration in active tissues.
(4)

A
  1. CO2 (increased) respiration
  2. (increased) dissociation of oxygen from haemoglobin
  3. low partial pressure in tissue/plasma
  4. oxygen diffuses from RBC to tissues
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16
Q

The oxygen dissociation curve of the foetus is to the left of that for its mother. Explain the advantage of this for the foetus.
(3)

A
  1. higher affinity (loads more oxygen)
  2. at low/same/high partial pressure
  3. oxygen moves from mother to foetus
  4. tissues will have a slightly lower pO2 and steep curve means oxygen will still ubnload at tissue when required.
17
Q

Explain how oxygen is loaded, transported and unloaded in the blood.
(6)

A
  1. haemoglobin carries oxygen / has a high affinity for oxygen / oxyhaemoglobin
  2. in red blood cells
  3. loading/association in lungs
  4. at high p.O2
  5. unloads/dissociates/releases to respiring tissues
  6. at low p.O2
  7. unloading linked to higher concentration of CO2
18
Q

Explain the process of aerobic respiration for high altitude/foetuses/lug worms.

A
  1. partial pressure of O2 at lung/of environment is low
  2. haemoglobin has a high affinity for oxygen
  3. more O2 is loaded (associates) at a lower partial pressure of oxygen
  4. this is then transported to the tissues
  5. for use in aerobic respiration

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