Biochemistry...

Question

. A molecule is described to you as an aliphatic, polar glycolipid. Which of the following statements must then be true for the molecule (select all that are correct);

a) it is soluble in water

b) it must contain a nitrogen atom

c) one part of the molecule contains a charge

d) part of the molecule is hydrophobic and part is hydrophilic

e) the molecule contains a lipid bound to an amino acid

f) the molecule contains a carbohydrate residue

g) the molecule has a ring structure

Answer 1

Dear Gytis,

The first step for this question is to understand what they are asking with regards to the compound in question--it is an aliphatic, polar glycolipid.

Aliphatic: it has an open carbon chain structure, as opposed to compounds containing pi-system rings (aka aromatics). Aromatics and aliphatics are mutually exclusive categories. This compound is a straight chain of carbons.

Polar: the compound have regions of positive and negative charge, which is what creates the polarity across the compound.

Glycolipid: breaking this term down, it quite literally means a lipid that is attached to a carbohydrate (hence the glyco-) via a covalent bond.

Now let's take a look at the answer choices.

a: correct--this molecule is polar, which would imply that it is soluble in water

b: incorrect--nitrogen is not implied through the description of this compound. This would be seen in amide and amine groups

c: correct--this molecule is polar, meaning that it does have regions of different charges

d: incorrect--this refers to a molecule that is "amphipathic"

e: incorrect--the lipid is attached to a carbohydrate, not an amino acid

f: correct--this molecule is a lipid contained to a carbohydrate

g: incorrect--this refers to an aromatic compound, but this one is aliphatic

In summary, the correct answer choices are: A, C, F