It should say the bonds holding the two DNA strands together are noncovalent hydrogen bonds. It says "The nucleotides forming each DNA strand are connected by noncovalent bonds, called hydrogen bonds." but those are covalent peptide bonds. Ribose instead of deoxyribose is drawn in the dehydration synthesis diagram. These bonds are called 3’-5’ phosphodiester bonds"? So shouldn't it say "The phosphodiester bonds that join one DNA nucleotide to another always link the 3’ carbon of the first nucleotide to the 5’ carbon of the second nucleotide. C and T bases, which have just one ring, are called pyrimidines, while A and G bases, which have two rings, are called purines. These bonds are called 5’-3’ phosphodiester bonds." but DNA is synthesized from 5' to 3' direction according to the "How DNA is replicated" video where the 5'C of the second nucleotide is always linked to the 3'C of the first nucleotide. A nucleotide is made up of a sugar (deoxyribose), a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), guanine (G) or cytosine (C). This is done by the sugar phosphate backbone twisting around itself in a coil. one runs 3' to 5', the other run 5' to 3'. DNA is wound into an right-handed double helix. A DNA molecule is composed of two strands. Figure 1 Diagram showing the sugar phosphate backbone of DNA, and the nitrogenous bases attached to it, forming a nucleotide. There are four nitrogenous bases in DNA, two purines (adenine and guanine) and two pyrimidines (cytosine and thymine). Figure 3.31 Three components comprise a nucleotide: a nitrogenous base, a pentose sugar, and one or more phosphate groups. Each nucleotide is composed of a nitrogenous base, a five-carbon sugar (deoxyribose), and a phosphate group. Each nitrogenous base in a nucleotide is attached to a sugar molecule, which is attached to one or more phosphate groups. It says "The phosphodiester bonds that join one DNA nucleotide to another always link the 5’ carbon of the first nucleotide to the 3’ carbon of the second nucleotide. The DNA molecule is a polymer of nucleotides. In the "nucleotide structure" diagram, deoxyribose is drawn but it says "ribose". The nitrogenous base (guanine in this example) is linked to the 1 carbon of the deoxyribose and the phosphate groups are linked to the 5 carbon.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |