adaptive advantage of haemoglobin (1 Viewer)

[Abtari]

anyone pls shed some light on this highly confusing terminology "adaptive advantage". is it talking about haemoglobin able to retain more oxygen once it has bonded with the first oxygen molecule (sigmasoidal curve shape).

or is it talking about how it is better than oxygen transported as dissolved in plasma which is not as efficient, etc.


help. thanxx

 

[xiao1985]

from my rotten notes of biology:
- high capacity to carry oxygen (4 oxygen molecule per heamoglobin macromolecule)
- included in blood cell (not upsetting osmotic balance)
- red cell has no nucleus, making it have more capacity to carry heamoglobin
- loosely attached to oxygen only... readily de attached where needed...

 

[Abtari]

adaptive advantage

thanks xiao.

but what do u mean when u say "included in blood cell (not upsetting osmotic balance)"?

also, i understand what uve written are four advantages of haemoglobin. what does the syllabus mean by ADAPTIVE advantage though???

also, since the dot point only mentions advantage (note singular term), do you think it could be looking for just one big advantage that we are overlooking right now (or that could be one from your list)????

just a bit concerned ... and annoyed.

 

[xiao1985]

hm as for advantage ... i'd tend to rmber as much as i can...

osmotic balance well if all the haemoglobin is in blood vessle then there's a relative high conc of blood of haemoglobin in vessle... water will diffuse out of cells if there's a gradient... energy is required to keep them in the cells.. other wise they'd go inflat... (sorry forgot the actual wording rather than inflat)

as for adaptive... i nver bothered with that term... my understanding is that since haemoglobin is a protein which cames about via evolution, why does it give its host an advantange in adapting to its environment...

 

[Abtari]

wow i didnt know that haemoglobin came about by evolution...well silly relly, considering all structures in the body came about by evolution!

ya, maybe in that evolutioanary sense, haemoglobin has an adaptive advantage.

thanks again

 

[malkin86]

It's an adaptive advantage because whilst oxygen can be carried dissolved in plasma, haemoglobin allows much much more oxygen to be carried... I think it's like 4 molecules of oxygen per haemoglobin, and there are hundreds of haemoglobins in a red blood cell.. I wish I could find some stats.

Iron (in the haemoglobin) joins strongly with oxygen - that's why iron rusts so much. However, it fairly easily breaks those bonds, which is why cellular respiration can take place.

pretty picture of a haemoglobin

 

[Abtari]

i see what u mean malkin86 but isnt it a bit contradictory to say that they form strong bonds and can separate easily? a bit confused about that still...

 

[xiao1985]

lolz that is rather outside the hsc syllabus...
wut's actually happening is in fact the Fe2+ is being "held" by the heamoglobin, and is "open" geometrically at one side where stuff can attach to it... oxygen having a pair of lone electrons which can bind to metal ions... this attraction however, is weakened in the presense of H+ ions (i think), which is precisely where CO2 is at most...

hence O2 is dissociated from heamoglobin where the acidity is greatest (H2CO3 is greatest) hence requriing most O2...

 

[malkin86]

Abtari, it's to do with chemistry - I'm not a chemistry girl, so I can't explain it any better than that. All I know is that it does that, and so that's all I can tell you. Sorry.

However, Xiaoie has given a very excellent expansion on what I said. Now if only I could understand it...

 

[Abtari]

no probs, thanks

 

[nit]

well the association of iron and oxygen is of an intermediate strength - that's what is meant by the fact that the dative bond between oxygen and iron can be broken easily. A similar concept holds for the hydrogen bonds holding duplex DNA together - the hydrogen bonds are of sufficient strength to maintain this double-stranded form, but are of low enough strength to be broken by the action of DNA helicase I think it is for DNA replication and RNA production.