Mastering Nucleotides and the DNA Helix

DNA nucleotides are composed of a pentose sugar (deoxyribose), a phosphate group, and either a purine (AG) or pyrimidine (CT) base. The DNA helix consists of two complementary strands that are antiparallel, with one strand being 3' to 5' and the other being 5' to 3'.

The 3' end of a DNA strand has a hydroxyl group (-OH) attached to the 3' carbon of the sugar, while the 5' end has a phosphate group (-PO4) attached to the 5' carbon of the sugar. These ends play a crucial role in DNA replication and synthesis.

During DNA replication, new nucleotides are always added to the 3' end of the DNA strand. This is because the enzyme responsible for DNA synthesis, DNA polymerase, can only add nucleotides in a 5' to 3' direction.

<p>Both bacterial and eukaryotic chromosomes have a similar DNA structure, which is highly conserved. They both contain genomic information and are composed of nucleotides. However, the organization of bacterial chromosomes is simpler and usually circular, while eukaryotic chromosomes are linear and more complex with histone proteins.</p> Signup and view all the answers

<p>When DNA structure is highly conserved, it means that it has undergone little change over the course of evolution. This suggests that the structure is essential for the survival and reproduction of organisms.</p> Signup and view all the answers