DNA is not read 3' to 5'. The DNA template strand is read 3' to 5' by enzymes like DNA polymerase, but the new DNA strand is synthesized in the 5' to 3' direction.
Explanation
Although the template strand that guides DNA replication or transcription is read from 3' to 5', the resulting DNA or RNA strand is built in the opposite direction, from 5' to 3'. This is due to the mechanism of DNA polymerase, which can only add nucleotides to the 3' end of a growing strand. Therefore, new DNA is synthesized 5' to 3'.
- DNA Polymerase: This enzyme adds nucleotides only to the 3' end of a DNA strand.
- Direction of Synthesis: New DNA strands are always synthesized in the 5' to 3' direction.
- Template Reading: To synthesize a new strand 5' to 3', the template strand must be read in the 3' to 5' direction.
In summary, DNA polymerase moves along the template DNA strand in the 3' to 5' direction but lays down new nucleotides forming a complementary strand in the 5' to 3' direction.
