[klp2332]

Hi Guys,

I was wondering if you get any precipitate from 2ml Lactose 3ml Lactase, and 2ml Benedicts. Lactose should hydrolyse into Glucose + Galactose. Will Benedict's copper(II) ions (Cu2+) get reduced because of the Glucose and precipitate?

If yes, about how much of precipitate would I get in terms of milligrams with those kind of values.

Also does light affect the speed of oxidation. If yes, would it apply to the chemical reaction that takes place with Bendict's solution and glucose?

Thanks

[AWK]

Write down a stoichiometry of reaction.

You should know at least a concentration of lactose

Some printed error corrected

[klp2332]

the amount of precipitate is not that important, but having it or not is.
I should have specified concentration anyways,

10% Lactose, 2% Lactase

Thanks

[klp2332]

*Ignore me, I am impatient*

[Arkcon]

We'd like to see what you know about:

What lactase is, and what it does.  FWIW, your amounts and concentrations seems screwy to me, can you see anything wrong?

You've given us the reaction of lactase with lactose, and the products, that's good.  That helps us not have to re-teach you the very basics, and helps us know what level to speak to you at.

We'd like to hear from you what the reaction with Benedict's Solution is.  You've left out an important, additional, piece of info to answer your specific question.  Do you know what it is?

As for the effect of light -- can you offer a mechanism?

[klp2332]

I was actually not looking for any in depth answers, but just some yes or no's to help me clear some things in my head.

I did make a mistake in my concentrations, it should be 5% Lactose 2% Lactase.

Benedict's Solution is use as a test for the presence of reducing sugars, which applies to Glucose. If what I know is correct then the blue copper(II) ions (Cu2+) in Benedicts Solution will be reduced to copper(I) (Cu+)forming a red precipitate.

Basically,
1. Will there be a precipitate? from Lactase+Lactose+Benedicts

2. If yes, roughly how much of precipitate would I get in terms of milligrams with those kind of values.

3. Does light affect the speed of oxidation. If yes, would it apply to the chemical reaction that takes place with Bendict's solution and glucose

4. Would UV rays affect this reaction?

Mechanism for light would not matter, just need a simple answer to question 3. But if it is necessarily, then sunlight through the window, or lamps.

Thanks Arkcon for having an interest

[Arkcon]

I was actually not looking for any in depth answers, but just some yes or no's to help me clear some things in my head.

Briefly, we don't do that here.  The forum rules specify, we don't give out free answers, write lab discussions for you, etc.  We do Socratic learning here -- you ask a question, we answer with a question, that leads to an answer, so you learn new things -- it's less like cheating, and you learn more that way, and are better off on exams.  And this board ends up less attractive to people who don't want to learn, and more attractive to people with interesting things to talk about.

What does you lab writeup or text book tell you about the enzyme lactase, and Benedict's solution?  And can you use that info to work out your problem yourself, or is there some small point that's confusing that we can help with.

And this ambient light thing, why do you keep mentioning it?  This is a bog standard, high school level assay, developed a century ago.  It's never done without light, because humans can't see a precip. without light.  Is this a question on your lab practical, or are you trying to explain away an anomalous result with a "maybe sunlight did it" bit of handwavium, like this unfortunate person here: http://www.chemicalforums.com/index.php?topic=25346.msg95811#msg95811

If yes, about how much of precipitate would I get in terms of milligrams with those kind of values.

the amount of precipitate is not that important, but having it or not is.
I should have specified concentration anyways,

10% Lactose, 2% Lactase

2. If yes, roughly how much of precipitate would I get in terms of milligrams with those kind of values.

Pick one.