The 5' end of a polynucleotide refers to the terminal end that has a free phosphate group attached to the fifth carbon of the sugar molecule. The correct statement about the 5' end of a polynucleotide DNA chain is that the 5' end has a hydroxyl group attached to carbon number 5 of ribose. To explain this, a nucleotide, the basic component of polynucleotide chains such as DNA and RNA, is composed of a nitrogenous base, a sugar (ribose in RNA or deoxyribose in DNA) and one or more phosphate groups. The carbon atoms in the sugar molecule are labeled 1', 2', 3', 4' and 5'.The phosphate group is attached to the 5' carbon by forming an ester bond between phosphoric acid and the 5'-OH group, hence we call it the 5' end of the chain.
Statement 2 is incorrect because the value 5' does not refer to the position in the nitrogenous bases but in the pentose sugar. A) One end has a free phosphate residue on the 5′ end of the ribose sugar. It is marked as the 5′ end of the polynucleotide. The polynucleotide is defined as a long chain of nucleotides linked together by phosphodiester bonds, which can have various lengths and sequences of nitrogenous bases, allowing for the storage of complex genetic information.
Complementary base pairing means that a larger purine always binds to a smaller pyramidine, maintaining a constant distance between the two main strands of DNA and resulting in parallel polynucleotide chains. Both DNA and RNA are polynucleotides linked together by phosphodiester bonds between the ribose moiety of the nucleotides. Nucleotides are more complex than peptides; therefore, polynucleotides, when single-stranded, can be expected to be even more polymorphic than polypeptides. A polynucleotide consists of many monomers called nucleotides and is considered to be the building block of all nucleic acid molecules.
This means that the respective 5' and 3' carbons are exposed at each end of the polynucleotide, so they are referred to as the 5' end and the 3' end. Nucleotides constitute the monomeric units that make up nucleic acids; this means that nucleic acids are polynucleotides. The main characteristics of DNA are: (i) It is made up of two polynucleotide chains (ii) The backbone is made up of sugar and nitrogen bases (iii) Two chains have parallel polarity (iv) The bases of two chains are paired by H bonds (v) The two chains are wound on the left. The genetic material of the nucleus is DNA, and each molecule consists of two polynucleotide chains arranged in a double helix.
Each polynucleotide chain has a 5' end and a 3' end, and the two run antiparallel (in opposite directions) within the DNA. The ability to cause two chains of polynucleotides, either DNA or RNA, containing complementary base sequences, to hybridize to form a double helix has proven to be of great value in various areas of nucleic acid research and technology. The 5' end of a polynucleotide chain of DNA refers to the end of the DNA molecule where the sugar (deoxyribose) has a phosphate group attached to the fifth carbon. This can be considered as the primary structure of polynucleotides, but it gives little indication of the shape that the molecule similar to a long chain takes in the cell.
Like the primary structure of a polypeptide, polynucleotides have a sequence of side chains, in this case, bases. The asymmetry of the nucleotides and the manner in which they bind result in an inherent polarity of the polynucleotide chain with a free 5' phosphate or 5' hydroxyl at one end and a free 3' phosphate or 3' hydroxyl at the other. Watson and Crick proposed that a DNA molecule consists not of one but of two polynucleotide chains wrapped around each other. to form a regular double helix.
