Biology Unit 3 Questions Megathread

[WhoTookMyUsername]

lol should have made this clearer

*those were examples i thought of from different perspectives, any refinement possible ?

[lexitu]

Oh okay

In that case I would rid with the term 'precursor' (bio uni people please confirm that it's not ideal here) but keep something similar to that definition.

[WhoTookMyUsername]

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I looked up synonyms for precursor.

I don't think herald fits well !
But yeah, i think there should be a better word (not sure what it is)

[lexitu]

I think it's not the correct term in that glucose doesn't in any way become ATP (again, I'm not 100% sure on this). You could just say it is used to resynthesise ATP.

[WhoTookMyUsername]

m... probably
The - add descriptive word descriping neccesity / order(fundamental?) source of energy to synthesise ATP?

[lexitu]

Umm yeah something like that. I think synthesise gives the wrong impression though...

[TrueLight]

Pretty sure it can be used for either, but usually tertiary as most proteins don't have a quaternary structure.

i reckon most proteins form a quaternary structure because you get proteins forming complexes with other proteins in most of the cases i can think of

look here for eg
http://vce.atarnotes.com/forum/index.php/topic,26528.msg268958.html

[WhoTookMyUsername]

m... yeah i doubt they'll end up asking that, do you have a defintion for the role of Glucose as a source of energy?

(simply saying, glucose is a asource of energy, is not really great because starch, glycogen, fat are all sources of energy

the 'predominant' (precursor?) to ATP?

[Russ]

Just call it a requirement for cellular respiration to occur

[HERculina]

Is glycogen water-soluble because it has more alpha -1,6 glycosidic links?

[Russ]

More links than what?

I'm trying to think of how that would affect solubility and can't think of anything. It's the OH groups that determine it.

[HERculina]

hm im confused  :buck2:
 it says in my workbook that glycogen is more highly branched and water-soluble than starch cause it has more alpha-1,6 glycosidic links than alpha -1,4 ones.

[pi]

hm im confused  :buck2:
 it says in my workbook that glycogen is more highly branched and water-soluble than starch cause it has more alpha-1,6 glycosidic links than alpha -1,4 ones.

Glycogen is more soluble than starch (even though they both have 1,6 glycosidic links and alpha -1,4 ones) because starch exists in general as an alpha helix while glycogen is a more highly branched and random structure. In the alpha-helical conformation there are less exposed -OH (hydroxide) groups to the solution making the starch less hydrophilic than the glycogen. As there are less OH groups available to from hydrogen bonds with the polar water molecules, that is why starch is less soluble.

It is due to this 'extra' branching that glycogen has that enables it to be more soluble.

Hope that helps.


(this specific stuff will never come up in the exam btw)

[ggxoxo]

People I need help please!!! ASAP!!! My class is doing a SAC on osmosis right now and we are testing potato cylinders. Now we are putting the potato cylinders in different sucrose concentrations. Our control is potato cylinder in distlled water. However apparently it is not a 'true' or 'valid' control. why is that? Please reply ASAP!

[WhoTookMyUsername]

Because it is not truly isotonic