5.Molecular Basis of Inheritance
medium

Antiparallel strands of a $DNA$ molecule means that

A

one strand turns clockwise

B

one strand turns anti­clockwise

C

the phosphate groups of two $DNA$ strands, at their ends, share the same position

D

the phosphate groups at the start of two $DNA$ strands are in opposite position (pole).

(AIPMT-2006)

Solution

(d) : $DNA$ is a type of nucleic acid that forms genetic material in many organisms. It consists of a long polymer of nucleotides which transcribes the coded information in the form of a triplet code of nucleotides in $mRNA$. It is a double helical molecule. The two strands of $DNA$ run in opposite directions to one another with the hydrogen bonds between them. One strand of $DNA$ has $5'­3'$ direction and the other strand has $3'­5' $ direction. So they are antiparallel. This direction is determined by the presence of a free phosphate or $OH$ group at the end of the strand. If the strand has phosphate group at the the $5'$ end and with a free $OH$ group at the $3'$ end.

Standard 12
Biology

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