How to Differentiate Between Poisonous Snakes and Non Poisonous Snakes. Some snakes harm their prey by injecting venom through their fangs; some of this venom can be harmful to humans, resulting in what we often think of as poisoning...
DNA polymerases cannot initiate DNA synthesis - they can only add on to an existing strand of DNA or RNA. The existing strand is said to prime DNA synthesis. RNA polymerases, however, can begin copying a parent strand with no primer - just as they do in transcription of genes. During DNA replication, RNA primers are produced by RNA polymerases in order to provide a starting point for DNA polymerases to extend from.
RNA is usually single stranded while DNA is double stranded. RNA uses the base uracil instead of the base thymine used by DNA. RNA polymerase does not need to use the enzyme helicase to unwind the strands of DNA, nor does it need a primer to transcribe. DNA polymerase needs both to replicate DNA.NA uses the base uracil instead of the base thymine used by DNA. RNA polymerase does not need to use the enzyme helicase to unwind the strands of DNA, nor does it need a primer to transcribe. DNA polymerase needs both to replicate DNA.