Corresponding stereoisomers differ in biological properties. The inversion of just one stereocenter on a large, complex molecule can alter the biological properties of the entire molecule. All other statements are true.

A molecule is meso if it contains at least two stereocenters, but is rendered optically inactive by internal structural symmetry. In other words, a meso compound may be split in half in some way such that portions on either side of an imaginary line are mirror images. Note: The absolute configurations of a meso compound with two stereocenters are opposite (R/S). The internal symmetry that makes molecule III a meso compound is best conveyed through a Haworth projection:

There are two tetrahedral asymmetrical stereocenters in this molecule (the carbon atoms attached to each of the chlorine atoms). Thus, the combinations of R and S include RR, RS, SR, and SS. Note the plane of symmetry in the molecule; RS and SR are the same molecule (meso compounds). Thus, there are three distinct configurational stereoisomers of this compound.

Corresponding stereoisomers differ in biological properties. The inversion of just one stereocenter on a large, complex molecule can alter the biological properties of the entire molecule. All other statements are true.

A molecule is meso if it contains at least two stereocenters, but is rendered optically inactive by internal structural symmetry. In other words, a meso compound may be split in half in some way such that portions on either side of an imaginary line are mirror images. Note: The absolute configurations of a meso compound with two stereocenters are opposite (R/S). The internal symmetry that makes molecule III a meso compound is best conveyed through a Haworth projection:

There are two tetrahedral asymmetrical stereocenters in this molecule (the carbon atoms attached to each of the chlorine atoms). Thus, the combinations of R and S include RR, RS, SR, and SS. Note the plane of symmetry in the molecule; RS and SR are the same molecule (meso compounds). Thus, there are three distinct configurational stereoisomers of this compound.

If a molecule has n sterocenters, it has up to possible steroisomers. Thus, the given molecule has or possible stereoisomers. Keep in mind the key word here is maximum, where the molecule may have less than 32 steroisomers, for instance when discussing meso compounds.

If a molecule has n sterocenters, it has up to possible steroisomers. Thus, the given molecule has or possible stereoisomers. Keep in mind the key word here is maximum, where the molecule may have less than 32 steroisomers, for instance when discussing meso compounds.

2,3,4-trimethylpentane does not contain any stereocenters. The structure is a five-carbon chain, with the end carbons bonded to three hydrogens each. The three central carbons each carry a methyl group and a hydrogen atom.

Remember that a stereocenter is only present when a carbon is bound to four different substituents. The 2 and 4 carbons both have two methyl groups (the end carbons and the added groups), so they would contain a plane of symmetry and would not be stereocenters. Likewise, a plane of symmetry exists at the 3 carbon; the substituents toward the 1 carbon and 5 carbon are the same. This compound, therefore, would have no stereocenters and could only exist as one stereoisomer.

2,3,4-trimethylpentane does not contain any stereocenters. The structure is a five-carbon chain, with the end carbons bonded to three hydrogens each. The three central carbons each carry a methyl group and a hydrogen atom.

Remember that a stereocenter is only present when a carbon is bound to four different substituents. The 2 and 4 carbons both have two methyl groups (the end carbons and the added groups), so they would contain a plane of symmetry and would not be stereocenters. Likewise, a plane of symmetry exists at the 3 carbon; the substituents toward the 1 carbon and 5 carbon are the same. This compound, therefore, would have no stereocenters and could only exist as one stereoisomer.