Biology Forums - Study Force

From the link:

For the following questions, which would it be?

-from A to B
-B to A
-B to C
-C to B

1) the blood pH drops from 7.4 to 7.2
2) The blood CO2 concentration increases
3) THe concentration of 2,3-biphosphoglycerate increases during acclimation to high altitude
4) An infant's fetal hemoglobin (HbF) is replaced by normal adult hemoglobin (HbA)
5) Hemoglobin is isolated from red cells and stripped of 2,3-biphosphoglycerate
6) Tetrameric hemoglobin is dissociated into its subunits.

Hi, thanks for joining!

(1) When pH decreases, you get a shift to the right so (c) [Remeber, right shifts show decreased affinity]
(2)  2,3-biphosphoglycerate binds with greater affinity to deoxygenated hemoglobin (e.g., when the red cell is near respiring tissue) than it does to oxygenated hemoglobin (e.g., in the lungs). In binding to partially deoxygenated hemoglobin, it allosterically upregulates the release of the remaining oxygen molecules bound to the hemoglobin, thus enhancing the ability of RBCs to release oxygen near tissues that need it most. You should see a shift to the right (c)
(3) (B)
(4) (A) Red blood cells wouldn't be able to release the oxygen (Highly saturated)
(5) (A) Because there would be any cooperatively anymore (similar to myoglobin)

Bio_man

Also, go through this tutorial, I had it saved in my favourites:

http://higheredbcs.wiley.com/legacy/college/boyer/0471661791/structure/HbMb/hbmb.htm (http://higheredbcs.wiley.com/legacy/college/boyer/0471661791/structure/HbMb/hbmb.htm)

Here is a second link to help you with this problem:

http://tinyurl.com/26ct544 (http://tinyurl.com/26ct544)

Message me if you need further clarification.

Bio_man I think you skipped a question

1. B -> C
2. B -> C
3. B -> C
4. A -> B
5. B -> A
6. B -> A

These answers work if B is baseline or "normal"

The causes of shift to right can be remembered using the mnemonic, "CADET, face Right!" for CO2, Acid, 2,3-DPG, Exercise and Temperature.

A rightward shift indicates that the haemoglobin under study has a decreased affinity for oxygen. This makes it more difficult for haemoglobin to bind to oxygen (requiring a higher partial pressure of oxygen to achieve the same oxygen saturation), but it makes it easier for the haemoglobin to release oxygen bound to it. The effect of this rightward shift of the curve increases the partial pressure of oxygen in the tissues when it is most needed, such as during exercise, or haemorrhagic shock.

In contrast, the curve is shifted to the left by the opposite of these conditions. This leftward shift indicates that the haemoglobin under study has an increased affinity for oxygen so that haemoglobin binds oxygen more easily, but unloads it more reluctantly.

chels194, I'm assuming this is for 2nd year biochemistry?

Thanks guys but somehow # 4 isnt correct. The one about infant fetal hemoglobin. Any ideas?

Functionally, fetal hemoglobin differs most from adult hemoglobin in that it is able to bind oxygen with greater affinity than the adult form (see attachment). This is because fetal hemoglobin binds less strongly to BPG and, consequently, has a greater affinity for oxygen.  So like if it were replaced with regular hemoglobin, it would go from A to B wouldn't it? I mean using this logic, it kind of makes sense.

What did you come up with?

I'm not really sure what it is. It just wasn't correct. I don't know the right answer yet. Could it might be from B to A?

No, impossible because B is base line. It only shifts to the right when there is an increase in CO2, Acid, 2,3-DPG, Exercise and Temperature.

4) An infant's fetal hemoglobin (HbF) is replaced by normal adult hemoglobin (HbA)

It could also be A -> C, but I'm sticking with A->B

But there's no answer choices with A to C.

I will explain to you why it's not B to A. B represents normal adult hemoglobin, as you can see it is somewhat of a sigmodial S shape. This indicates cooperatively when binding (i.e. when the first oxygen binds, there is an increase in affinity for the second binding site; when the second binding site has an oxygen molecule bound, the third now has more affinity, so on and so forth). However, we know that fetal hemoglobin has very high affinity for oxygen (so it gets saturated really quickly, as shown in (a)). It wouldn't make sense to go from B to A for this reason.

i found out what it was bio_man, the corrrect answer was from B to C.