Login

Join for Free!
118233 members


can galactose be convert into fructose?

Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.

Moderator: BioTeam

can galactose be convert into fructose?

Postby teyya » Wed Aug 26, 2009 5:58 am

hi all.i need to ask some questions...because it was asked by my lecture...in glycolysis process,why glucose cannot be phosphorylated two times and directly converted to glucose-1,6 biphosphate instead of fructose 1,6 biphoshpate?..and secondly, can galactose be transformed to fructose? i need ur help......
teyya
Garter
Garter
 
Posts: 3
Joined: Thu Aug 20, 2009 10:32 am

Re: can galactose be convert into fructose?

Postby mande » Wed Aug 26, 2009 10:01 am

Since I have yet to learn about phosphorylation, I can only answer your second question about 'the transformation of galactose to fructose'.

If I'm not mistaken, no, galactose cannot be transformed/converted to fructose (a sugar found in fruits). This is because both the aforementioned are monosaccharides.

a) glucose + glucose => maltose
b)glucose + galactose => lactose
c) glucose + fructose => sucrose

On another note, these two simple sugars are likely to compete with each other in a certain condition as such I have read on Wikipedia.

"Fructose absorption occurs via the GLUT-5[32] (fructose only) transporter, and the GLUT2 transporter, for which it competes with glucose and galactose. A deficiency of GLUT 5 may result in excess fructose carried into the lower intestine.[citation needed] There, it can provide nutrients for the existing gut flora, which produce gas. It may also cause water retention in the intestine. These effects may lead to bloating, excessive flatulence, loose stools, and even diarrhea depending on the amounts eaten and other factors."

I know the last part may not be of help but I hope I have helped in some way! And if i'm wrong, then feel free to correct me because there is learning through mistakes!
mande
Garter
Garter
 
Posts: 2
Joined: Wed Aug 26, 2009 8:51 am

Postby MrMistery » Sat Aug 29, 2009 2:36 pm

monosaccharides can be converted into one other, otherwise you could never utilize any other sugar than fructose or glucose. Galactose for example can be converted to glucose via Galactose-1-phosphate uridyl transferase. fructose can be phosphorylated by fructokinase, from where it enters the glycolysis pathway, which can then generate glucose by running in reverse.

Of yeah and the stuff about transporters has nothing to do with the metabolism part.

As for the first question, I can only guess that it is a more favorable reaction to phosphorylate a hydroxyl group on the chain (carbon 1) in a ketose sugar than any of the hydroxyl groups inside the ring of an aldose sugar (aldose sugars like glucose do not have a hydroxyl group on Carbon 1 and have a carbonyl group instead. You need a hydroxyl group to create the phosphoester bond during the phosphorylation reaction).
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
User avatar
MrMistery
Inland Taipan
Inland Taipan
 
Posts: 6832
Joined: Thu Mar 03, 2005 10:18 pm
Location: Romania(small and unimportant country)


Postby teyya » Mon Aug 31, 2009 3:17 pm

thanks...
teyya
Garter
Garter
 
Posts: 3
Joined: Thu Aug 20, 2009 10:32 am


Return to Molecular Biology

Who is online

Users browsing this forum: No registered users and 4 guests