Where are hydrogen bonds located in nucleic acids and carbohydrates?

Question

I'm having trouble answering the following questions: “where would you find hydrogen bonds in nucleic acids?” “where would you find hydrogen bonds in carbohydrates”?

Answer 1

Gabriel: A key here is that hydrogen bonds are relatively weak interactions BETWEEN molecules. So a COVALENT bond between an oxygen and hydrogen in one water molecule, for example, is NOT a hydrogen bond.

 

The origin of hydrogen bonding is the unequal 'sharing' of electrons between a hydrogen (with a weak 'pull' on electrons, more formally a relatively low electronegativity) and generally an oxygen or nitrogen that the H is covalently bonded TO. Another way of looking at it is:

H--->O<---H, where the arrowheads indicate the Oxygen is 'winning' the tug-of-electrons.

 

This leaves the HYDROGEN somewhat positive overall (because it's 'lost' its fair share of electrons) and the oxygen correspondingly negative.

 

A hydrogen bond is the interaction that results between the somewhat-postive H from ONE molecule and the somewhat-negative O or N on ANOTHER.

 

Note that carbon also has a relatively weak electron pull, so oxygens & nitrogens that are covalently bonded to carbons are also somewhat negative in charge and can participate in H-bonds on other molecules.

 

If you look at HOW two bases in DNA or RNA are interacting, you should be able to see the H-bonds! (H-bonds are often shown as dashed lines to indicate they are different & weaker than covalent bonds)

Answer 2

Hydrogen bonds occu when a H atom is bonded to a N, O or F atom. So in nucleic acids hydrogen bonding occurs between adenosine and thymine bases and between cytosine and guanine bases.  In carbohydrates,hydrogen bonding occurs between the -OH groups on the molecules.