AP Biology Question

Question

A researcher hypothesizes that a certain chemical reaction performed by cells is a polymerization reaction. To study this reaction in more detail, she replicates the reaction in a test tube.What would most support her hypothesis?

The concentration of water would increase

The concentration of water would decrease

The concentration of reactants would increase

The concentration of reactants would decrease

I chose the concentration of water would increase. I remember my teacher explaining a little about it, and I simply just don't know what or how my answer would be correct (if it even is correct).

If you can, please provide an explanation! Thank you.

Answer 1

Hi Galena,

I agree with the answer you chose. Many polymerization reactions take place via condensation reactions, producing water as the chain is elongated.

Say you are working with a growing amino acid chain and wanting to produce a peptide. The lone pair of the amino group on the proceeding amino acid will attack the activated carbonyl carbon of the C-terminus. This will kick off water in the process to maintain its sp² planar geometry. The same process occurs for polysaccharides. A water molecule is lost as the anomeric carbon forms a glycosidic bond with its proceeding monosaccharide. In both cases, an increase in the concentration of water would suggest that these polymers are forming, facilitated by a loss of water from the conjoining monomeric units.