Molecules of the amino acids that comprise our proteins have the property of being non-super imposable on their mirror images because,. They are said to be chiral or possess 'handedness'. Most of the amino acids are of left handed form, but with no reasons available. Even more interesting recent experiments have shown that a 7-9% excess of four amino acids is present in Murchison meteorite discovered in 1970. This analysis shows life could arise outside the confines of earth. The origin of unequal distribution is probably because of electromagnetic radiations emitted in a corkscrew fashion from the poles of spinning neutron stars could lead to a bias of one mirror image isomer over another when molecules form in interstellar space.
A stereogenic carbon can be defined as a carbon atom bearing groups of such nature that an interchange of any two groups will produce a stereoisomer. The device that is used for measuring the effect of optically active compounds on plane polarized light is a polarimeter. The analyser in the polarimeter decides the activity of compound present. This is being decided on the basis of angle by which axis of analyser has to be rotated for complete brightness. Left, right or no adjustment decides l, d - activity or optical inactivity respectively.
Stereogenic carbons can bring

Options

A. optical activity
B. optical inactivity
C. both
D. None of the above

Answer

To solve the question regarding stereogenic carbons and their properties, let's break down the information step by step.

### Step-by-Step Solution:

1. **Understanding Stereogenic Carbons**:
- A stereogenic carbon (also known as a chiral carbon or asymmetric carbon) is defined as a carbon atom that is attached to four different groups. The presence of four distinct groups allows for the formation of two non-superimposable mirror images, known as enantiomers.

**Hint**: Remember that for a carbon to be stereogenic, it must have four different substituents.

2. **Identifying Optical Isomerism**:
- Optical isomerism occurs when a compound can exist in two forms that are mirror images of each other. These forms are not superimposable, meaning they cannot be aligned perfectly like left and right hands. This property is a direct result of the presence of stereogenic carbons.

**Hint**: Think of optical isomers as "handedness" - just like your left and right hands are mirror images but not identical.

3. **Example of Amino Acids**:
- In the context of amino acids, the alpha carbon (the central carbon in the amino acid structure) is typically a stereogenic carbon. For example, in the amino acid alanine, the alpha carbon is bonded to an amino group (NH2), a carboxyl group (COOH), a hydrogen atom (H), and a methyl group (CH3). This configuration makes it a chiral center.

**Hint**: When analyzing amino acids, look for the central carbon that connects different functional groups.

4. **Conclusion on Optical Activity**:
- Since stereogenic carbons lead to the formation of optical isomers, compounds with stereogenic centers will exhibit optical activity. This means they can rotate plane-polarized light, and the direction of rotation (left or right) will depend on the specific isomer.

**Hint**: Optical activity is a key characteristic of chiral molecules; if a molecule has a stereogenic carbon, it is likely to show optical activity.

### Final Answer:
The answer to the question is that stereogenic carbons can bring about **optical activity** due to their ability to form non-superimposable mirror images (optical isomers).