Skip to main content
Chemistry LibreTexts

SC8. Biological Building Blocks: Carbohydrates

SC8. Biological Building Blocks: Carbohydrates

 

  • The naturally-occurring carbohydrates are chiral.
  • Glyceraldehyde is the grandmother of carbohydrates.

 

 

Wire Frame

Ball & Stick

Spacefilling

 

Wire Frame

Ball & Stick

Spacefilling

  • The "last" chiral center in other carbohydrates all have the same configuration as the chiral center in glyceraldehyde.

  • Fischer projections are drawings that are sometimes used to show stereochemistry in a different way.
  • The groups to left and right of the Fischer projection are coming towards you.
  • The groups on top and bottom are going away from you.
  • The carbon chain is drawn vertically with attachments at the sides.
  • Normally, the chain is oriented so that the "highest priority functional group" on the chain is at or near the top of the chain; that usually means the group with the most bonds to oxygen.  In glyceraldehyde, the CH=O group is drawn at the top rather than at the bottom.
Problem SC8.1.

What is the absolute configuration of L-glyceraldehyde?  What about D-glyceraldehyde?

Problem SC8.2. 

Draw the following molecules as Fischer projections.

Problem SC8.3. 

Convert the following Fischer projections into wedge-dash drawings.