Question

DNA and RNA strands have a directionality. True or False?

Answer 1

It is true that DNA and RNA strands have directionality, with DNA strands running antiparallel to each other and RNA being single-stranded. Both types of nucleic acids have a precise 5' to 3' direction, which is critical for biological functions such as replication and the formation of RNA's three-dimensional structure.

Step-by-step explanation:

True or False: DNA and RNA strands have a directionality. This statement is true. Nucleic acid chains such as DNA and RNA indeed have polarity. A DNA molecule consists of two strands that run in opposite directions. These strands are known as the antisense strand and the sense strand, with the antisense strand running from 3' to 5' and the sense strand from 5' to 3'. This antiparallel arrangement is essential for many biological processes, including DNA replication, where one of the two strands is synthesized continuously from the 5' to the 3' end.

The bases in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T), and the strands are held together by Watson-Crick base pairing, where A pairs with T, and C with G. In contrast, RNA is typically single-stranded and contains uracil (U) instead of thymine. Despite being single-stranded, RNA can fold upon itself, creating a three-dimensional structure stabilized by short areas of complementary base pairing within the molecule.

Rosalind Franklin and R.G. Gosling played a critical role in demonstrating the helical nature of DNA, and their work was instrumental in understanding the molecular structure we are familiar with today.

Answer 2

DNA and RNA strands do have directionality, with chains starting with a 5' phosphate and ending with a 3' hydroxyl group, extending from 5' to 3'. DNA strands are antiparallel in the double helix structure, while RNA can fold upon itself and form three-dimensional structures.

Step-by-step explanation:

True, DNA and RNA strands have a directionality. Nucleic acid chains, including those of DNA and RNA, exhibit polarity. They start with a 5' phosphate group at one end and terminate with a 3' hydroxyl group at the other, thus depicting a distinct direction from 5' to 3'. This directionality is the same principle as protein chains going from N-terminus to C-terminus.

In the structure of double-stranded DNA, the strands are antiparallel; one strand runs in the 5' to 3' direction (known as the top strand), while the complementary strand runs in the 3' to 5' direction (the bottom strand). These orientations are crucial for various biological processes, such as DNA replication and transcription, where the 5' to 3' sequence of the template strand is used by enzymes like DNA and RNA polymerase to synthesize new strands. The antiparallel nature of the two strands ensures proper base pairing, with adenine (A) pairing with thymine (T) in DNA, and cytosine (C) pairing with guanine (G).

For RNA, although it is usually single-stranded, it can still exhibit base pairing within its strand, folding upon itself to create a unique three-dimensional structure that is essential for its function. This intrastrand base pairing also follows the same principle of complementarity as DNA.