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.
For existence of life, amino acids as ingredient of protein exist mainly in

Options

A. l-form
B. d-form
C. both
D. None of the above

Answer

A