2 questions on atp and galactose

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vicereine
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2 questions on atp and galactose

Post by vicereine » Fri May 09, 2008 6:59 pm

I'm currently taking a biology correspondence course and would like some help/feedback on the following questions:

How does the structure of ATP make it an effective energy carrier? Where does the energy stored in the molecules come from and how is it released?

Accurately describes the structure of ATP - 7 marks
Correctly lists where the stored energy comes from - 3 marks
Describes how it is released - 3 marks


My answer:
ATP is a molecule that has a structure composed of an adenine base with a ribose sugar and three phosphate groups. It is an effective energy carrier because it is highly soluble and the phosphate bonds are weak. Energy is stored in these phosphate bonds, so when a hydrolysis reaction occurs the bond of the last phosphate group breaks and the energy is released, converting ATP into ADP (and AMP when losing two phosphates).

I don't feel like I've written enough for 13 marks, but I'm not sure what else there is to say? and to "list" where the energy comes from? Sometimes I wonder if they just try to make some of these questions worth more marks because they aren't very long lol.

And

Lactase hydrolyzes lactose into glucose and galactose. Galactose is then converted to another glucose by galactosidase. State the reactions involving these enzymes using word equations. 2x3=6 marks


My answer:

.........lactase + H2O
lactose -----------------> glucose + galactose


............galactosidase
galactose ----------------> glucose

At first I was confused because galactose is a monosaccharide, so how could it be turned into glucose, but now I see that they are almost identical in structure, so I assume galactosidase changes the order of the molecules in galactose to the order they are in glucose. Hope I make sense. So is my word equation right? And is that all they're asking for? (does that state the reaction)

Thanks in advance.

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mith
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Post by mith » Fri May 09, 2008 7:33 pm

You could also note that the phosphates are negatively charged, and putting 3 negatively charged atoms together requires energy(stores).
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