Respiratory substrates in respiration

Hi, Wonder if anyone can help me with a biology topic. What is the actual science behind Glucose being a better respiratory substrate (in respiraion of say yeast) than sucrose? Is it simply because it takes time for the sucrose to be hydrolysed into glucose and fructose or is there more to it?

Cheers

Reply 1

GH

13

I don't think yeast can actually metabolize sucrose (I can't think of any living thing that can use complex carbohydrates per se-Maybe MadNatSci will totally shred this idea). Thus thats why it has sucrase to hydrolyse it to fruc and gluc.

Reply 2

Ben.S.

11

2776

I don't think yeast can actually metabolize sucrose (I can't think of any living thing that can use complex carbohydrates per se-Maybe MadNatSci will totally shred this idea). Thus thats why it has sucrase to hydrolyse it to fruc and gluc.

Sucrose is not a complex carbohydrate! It's just a disaccharide, like lactose. Hydrolysis of the carbohydrate is classed as part of the metabolic process, I think (lac operon for lactose metabolism in bacteria, for example) - so yeast can metabolise sucrose (otherwise, would you say orgainisms can only metabolise glucose, or fructose, or citrate?).

Ben

Reply 3

MadNatSci

12

2776

I don't think yeast can actually metabolize sucrose (I can't think of any living thing that can use complex carbohydrates per se-Maybe MadNatSci will totally shred this idea). Thus thats why it has sucrase to hydrolyse it to fruc and gluc.

Oi! I do NOT shred biochem ideas, I've got no idea about them for the most part! But Ben's argument sounds convincing, though I can't think of any helpful input to add here :smile:

Metabolism is an area that I have permanently blanked out of my brain :wink:

Reply 4

madmazda86

8

I haven't a clue about sucrose, but the reason why glucose is the best respiratory substrate out there is because it's already partially oxidised (lots of OH groups), so it's faster to use that during the Krebs Cycle :smile:

Respiratory substrates in respiration

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