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3: Exchange and Transport > Haemoglobin > Flashcards

Haemoglobin Flashcards

1
Q

Describe the protein structure of Hb. Include details of prosthetic groups.

A

Quaternary protein structure.
Contains 4 prosthetic haem (Fe2+) groups in each of the 4 polypeptide chains.

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2
Q

State the 3 IMFs/interactions present in the quaternary protein structure.

A

Disulfide bridges
Hydrogen bonds
Hydrophilic/hydrophobic interactions

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3
Q

Where does loading of oxygen occur and why?

A

Lungs.
High concentration of oxygen.

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4
Q

Where does unloading of oxygen occur and why?

A

Muscles.
Low concentration of oxygen, muscles require it for respiration.

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5
Q

What is loading/unloading?

A

Loading is the addition of oxygen to Hb.
Unloading is the loss of oxygen from Hb.

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6
Q

What is oxygen affinity?

A

How well a molecule is able to take up Hb.

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7
Q

If a Hb molecule has low oxygen affinity, what does this mean for loading/unloading?

A

Oxygen is taken up less easily.
It is released from Hb more easily.

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8
Q

If a Hb molecule has high oxygen affinity, what does this mean for loading/unloading?

A

Oxygen is added to the Hb more easily.
Oxygen is harder to lose from Hb.

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9
Q

Which 2 gases are able to alter the shape of Hb?
Why?

A

Gradual addition of oxygen Hb leads to changes in the shape of it.
Carbon dioxide also changes the shape of it as it is acidic. It makes the Hb bind more loosely to the oxygen, so oxygen is lost more easily.

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10
Q

Why are there different haemoglobins for different species?
What does this mean for oxygen affinity?

A

Different species produce different amino acid sequences, leading to different tertiary/ quaternary structures
Different Hb molecules will have different oxygen affinities.

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11
Q

Name the graph used to show how Hb associated with oxygen.

A

Oxygen dissociation curve.

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12
Q

What shape are oxygen dissociation curves typically?

A

S - Shaped

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13
Q

Why is the binding of the oxygen to the 1st Hb molecule difficult?

A

The polypeptide chains in the Hb molecules are closely united.

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14
Q

Explain why its more easy for the 2nd/3rd oxygen to bind to the Hb.
Name the affect that causes this.

A

The binding of the first oxygen changes the shape of the Hb. This makes it easier for other oxygen molecules to bind.
Positive cooperativity.

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15
Q

Explain why it is more difficult for the 4th oxygen to bind to the Hb.

A

Probability makes it harder for oxygen to bind as there is only 1 free binding site, so there is less chance of the oxygen finding a free space to bind.

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16
Q

What is partial pressure?

A

The concentration of oxygen in the body.

17
Q

What does it mean if an oxygen dissociation curve is further left?

A

There is a higher affinity for oxygen.

18
Q

What does it mean if an oxygen dissociation curve is further right?

A

There is a lower affinity for oxygen.

19
Q

What happens when partial pressure is higher in the lungs?

A

There is more oxygen association.

20
Q

What happens when partial pressure is lower in tissues?

A

Leads to more oxygen dissociation in the lungs.

21
Q

In the lungs, partial pressure is higher.
State the Hb oxygen affinity, concentration of CO2 (high/low) and whether O2 associates or not.

A

High oxygen affinity.
Low CO2 concentration.
O2 associates.

22
Q

In tissue, partial pressure is lower.
State the Hb oxygen affinity, concentration of CO2 (high/low) and whether O2 associates or not.

A

Low Hb O2 affinity.
High CO2 concentration.
O2 dissociates.

23
Q

What must happen for O2 to be transported efficiently?

A

Hb must be readily available at exchange surfaces and oxygen must dissociate readily at aerobically respiring tissues.

24
Q

Why does Hb have lower affinity for oxygen in the presence of CO2?

A

Presence of CO2 suggests that is is an aerobically respiring tissue that requires a supply of oxygen.

25
Q

Why is CO2 concentration lower at gas exchange surfaces?
How does Hb affinity for O2 change?
What is partial pressure in the lungs like?
This leads to…

A

CO2 is removed from the surfaces to be excreted.
Affinity of Hb increases.
Partial pressure of oxygen in the lungs is high.
This leads to loading of oxygen.

26
Q

Why is CO2 concentration high at respiring surfaces?
How does Hb affinity for O2 change?
Describe partial pressure of oxygen.
This leads to…

A

CO2 concentration high at respiring surfaces.
Affinity of oxygen is low.
Low oxygen concentration means low partial pressure.
This leads to unloading of oxygen.

27
Q

Give an equation for CO2 + H2O.
Then, give an equation for the breakdown of H2CO3.

A

CO2 + H2O -> H2CO3
H2CO3 -> HCO3n + H+

28
Q

What happens to CO2 at the exchange site?

A

It is excreted from the body.

29
Q

What happens to pH after CO2 is excreted?

A

pH raises.

30
Q

What does a higher pH do to the shape of Hb?

A

pH changes the Hb shape so oxygen can be loaded more easily.

31
Q

How does the change in Hb shape affect the oxygen affinity?
What is the benefit of this?

A

Change in Hb shape means oxygen affinity increases.
This means oxygen is not lost during transport.

32
Q

As CO2 is produced by respiring cells, what does this do to the blood concentration?

A

Higher CO2 concentration in the blood lowers its pH.

33
Q

As the blood pH is relowered, what does this do to the Hb molecule carrying the oxygen?

A

Hb reverts back to its original shape therefore the oxygen dissociates.

34
Q

The greater the CO2 concentration, the greater the….
Why?

A

Oxygen dissociation.
Higher carbon dioxide concentration changes the shape of Hb, so oxygen is lost more easily.

35
Q

Put this sequence into order:
Lowers pH
More CO2 produced by tissues
The more O2 readily available for respiration.
Higher rate of respiration.
The greater the shape change.
The more readily O2 is unloaded.

A
  1. Higher rate of respiration
  2. More CO2 produced by tissues
  3. Lowers pH
  4. The greater the shape change of Hb.
  5. The more readily O2 is unloaded.
  6. The more O2 readily available for respiration.
36
Q

Describe the Hb in llamas.

A

They live in an O2 depleted environment, so their Hb has a high oxygen affinity.
This means their oxygen dissociation curve shifts left.

37
Q

Describe the Hb in lugworms.
Why is it like that (where do lugworms live)?
What would the oxygen dissociation curve look like?

A

Live in an O2 depleted environment below sea level, so Hb has a high oxygen affinity.
Dissociation curve shifts left.

3: Exchange and Transport (8 decks)

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