Which of the Following Statements About the 5' End of a Polynucleotide

Question

Which of the following statements about the 5' end of a polynucleotide strand of DNA is correct?
A) The 5' end has a hydroxyl group attached to the number 5 carbon of ribose.
B) The 5' end has a phosphate group attached to the number 5 carbon of ribose.
C) The 5' end has phosphate attached to the number 5 carbon of the nitrogenous base.
D) The 5' end has a carboxyl group attached to the number 5 carbon of ribose.
E) The 5' end is the fifth position on one of the nitrogenous bases.

Accepted Answer

The 5' end of a polynucleotide strand of DNA has a phosphate group attached to the number 5 carbon of the ribose sugar. This phosphate group forms a covalent bond with the hydroxyl group at the 3' end of the adjacent nucleotide, forming the phosphodiester bond that links nucleotides together in the DNA strand.