Notes from NEET topper
Difference Between DNA and RNA
DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid) are two distinct types of nucleic acids found in cells, each with its own unique structure and functions. Here are the key differences between DNA and RNA:
- Sugar Molecule:
DNA: DNA contains deoxyribose sugar in its nucleotides. Deoxyribose is a five-carbon sugar without an oxygen atom in the 2’ position.
RNA: RNA contains ribose sugar in its nucleotides. Ribose is a five-carbon sugar with an oxygen atom in the 2’ position.
- Number of Strands:
DNA: DNA typically exists as a double-stranded molecule, with two long chains (strands) running antiparallel to each other in a double helix.
RNA: RNA is usually single-stranded, although it can form secondary structures by folding back on itself, resulting in regions of double-strandedness in some RNA molecules.
- Nitrogenous Bases:
DNA: DNA contains four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
RNA: RNA also contains adenine (A), cytosine (C), and guanine (G), but it replaces thymine (T) with uracil (U).
- Base Pairing:
DNA: In DNA, adenine (A) forms complementary base pairs with thymine (T), and cytosine (C) pairs with guanine (G). This complementary base pairing is the basis for DNA’s double helix structure.
RNA: In RNA, adenine (A) forms complementary base pairs with uracil (U), and cytosine (C) pairs with guanine (G).
- Function:
DNA: DNA primarily serves as the long-term storage of genetic information. It carries the instructions for the synthesis of proteins and other cellular components.
RNA: RNA has various functions, including carrying out protein synthesis through processes like transcription and translation. It can also have structural, catalytic, and regulatory roles in the cell.
- Location in Cells:
DNA: DNA is primarily found in the cell nucleus (in eukaryotic cells) and in the nucleoid region (in prokaryotic cells).
RNA: RNA is found throughout the cell, including the nucleus, cytoplasm, and various cellular organelles.
- Stability:
DNA: DNA is relatively stable and less susceptible to degradation because of the absence of the 2’-OH group in deoxyribose sugar.
RNA: RNA is generally less stable than DNA due to the presence of the 2’-OH group, which makes it more susceptible to hydrolysis.
- Types and Varieties:
DNA: DNA exists in a relatively consistent and uniform double-stranded form in most organisms, with variations in sequence.
RNA: RNA is more diverse and includes various types, such as messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), small nuclear RNA (snRNA), and others, each with specific functions.
