Haemoglobin

Question 1

What two forms does haemoglobin exist in? How do they differ?

Answer 1

T/Tense state

R/Relaxed state **COME BACK TO

Question 2

Which state of Hb has a lower affinity for O2?

Answer 2

T state

Question 3

Which state of Hb has a higher affinity for O2?

Answer 3

R state 
(Think relaxed hippy, welcoming and let's everyone in, someone's who's tense doesn't)

Question 4

Does fetal Hb have a lower or higher affinity for oxygen than maternal Hb? Why?

Answer 4

Higher affinity because it is less sensitive to 2,3-BPG

Question 5

Will the Bohr effect shift the oxygen dissociation curve to the right or left?

Answer 5

To the right (lower affinity)

Question 6

What agents bring about a shift to the right in a O2 dissociation curve? What change in affinity do they create?

Answer 6

CO2, 2,3-BPG, H+ all lower affinity for oxygen

Question 7

What is the benefit of feotal Hb having a higher affinity for O2 than maternal?

Answer 7

When the two blood supplies are near (IE in placenta) the O2 will travel from maternal to feotal blood.

Question 8

What is the effect of CO poisoning?

Answer 8

CO binds to Hb sub units- TF reducing no. available to O2.

When CO binds it increases the affinity of Hb for O2 TF when O2 binds it isn’t easily released.

Question 9

What would the effect of a drop in pH be on oxygen binding/release?

Answer 9

H+ bind to Hb molecule, by binding causes the creation of bonds which bring the subunits closer together–> promotes T state + lowers affinity for O2. O2 is more easily released.

Question 10

What would the effect of a drop in pH be on oxygen dissociation?

Answer 10

Curve shifts to the right–> Bohr Shift

Question 11

What would the effect of an increase in 2,3 BPG conc be on oxygen binding/release?

Answer 11

2,3 BPG binds to Hb molecule, causing bonds to form pulling sub units closer together and promoting T state- TF lower affinity for O2 TF O2 released more easily.

Question 12

What may cause an increase in 2,3 BPG?

Answer 12

More 2,3 BPG is released at higher altitude

Question 13

What would the effect of an increase in 2,3 BPG be on oxygen dissociation?

Answer 13

Curve shifts to the right- Bohr effect. Lower affinity for O2

Question 14

What is another name for 2,3 BPG?

Answer 14

2,3 DPG (2,3 bi/diphosphoglycerate)

Question 15

What is the benefit of the Bohr Effect?

Answer 15

Useful in metabolically active tissues- allows Hb to give up oxygen easier to supply rapidly respiring tissues with enough O2 to continue

Question 16

What conformational change brings about the T state of Hb?

Answer 16

When no oxygen is bound to Hb, the two αβ diners form ionic and H bonds which restrain movement and lower affinity of Hb for O2.

Question 17

What conformational change brings about the R state of Hb?

Answer 17

Once an O2 binds to a Hb subunit, some ionic and H bonds break raises the affinity of the Hb for O2 making it easier for other O2 to bind.

Question 18

What is cooperative binding?

Answer 18

Once one O2 molecule binds to a Hb subunit, it brings about a conformational change (by breaking some ionic and H bonds) which stabilises Hb’s R state, raising the affinity for O2 meaning it is easier for other O2 molecules to bind.

Question 19

Which state is deoxygenated- T or R?

Answer 19

T state

Question 20

Which state is oxygenated- T or R?

Answer 20

R state

Question 21

What is the benefit of having Fe ions bound to a protein like Hb rather than floating on its own?

Answer 21

Fe embedded in protein keeps it hidden and TF protected against damage from H2O. Which would lower its binding ability.

Question 22

How would you describe the dissociation curve of O2 for myoglobin?

Answer 22

Hyperbolic

Question 23

What is myoglobins function?

Answer 23

Designed to bind to the O2 that has been released by Hb, store it within muscles and then release it upon demand.

Question 24

How can myoglobin be a clinical marker?

Answer 24

Only present in muscles (eg heart and skeletal) TF when it’s present in blood stream- suggests muscle injury