Biology Education

Difference between Replication and Transcription

Main Difference

For an organism to grow, cell division is essential. But for cell division DNA of the cell must replicate so that the daughter cells have same genetic material as their parent cell. Transcription is a process in which sequence of DNA enzymatically copied by RNA polymerase to produce RNA. Transcription is basically transfer of genetic information from DNA into RNA. Both the processes involves the formation of new molecules of nucleic acid which can be either DNA or RNA. However, both DNA and RNA have different roles, with one involved in gene expression while other in cell division.

Replication

replicationReplication is a process involved in cell division which includes copying the DNA in a cell so that there will be two sets of DNA, each set of DNA is then available for daughter cell. Process of replication occurs in S-phase (synthesis phase) of cell cycle. In replication, first DNA unwinds and then DNA helix separates into two and each strand act as template for daughter’s cell DNA in which single DNA strand forms double stranded DNA. But before that RNA primer is required to start replication. Process of replication is catalyzed by DNA polymerase enzymes which recreates the complementary DNA sequence when the two DNA strands are separated. DNA replication involves copying of the entire genome. Deoxyribose nucleotide triphosphate act as raw materials which combines with the nucleotides of the single DNA strand which serve as a template through phosphodiester bond.  Hence, newly double stranded DNA helix is formed by the process of replication. This process helps to conserve the genetic information for the generation of cells and the individuals. Remaining products of replication are not degraded and remains within the nucleus.

Transcription

transcriptionTranscription is a process which involves copying of DNA into RNA. The part of DNA which codes for gene is copied into messenger RNA (mRNA) or transfer RNA (tRNA) or ribosomal RNA (rRNA). Process of transcription occurs in G1 and G2 phases of cell cycle. In transcription, first step is the untwisting and separation of the two DNA strands. RNA polymerase an enzyme which then travels along the length DNA strand and starts binding RNA nucleotides into the DNA strand, until a complete strand of RNA is formed. Then the mRNA comes into the cytoplasm through the nuclear pore of the nucleus where it is translated into proteins. Transcription takes place only in one strand of DNA and it allows copying of only certain amount of genes. So, single strand of RNA is formed from the one segment of DNA. No primer is required in transcription. Process of transcription helps to form DNA copies of genes which can be used in immediate production of proteins. Remaining products of the process of transcription are degraded when their function is over.

Key Differences

  • Replication is a process in which two DNA are formed from a single DNA while transcription is a process in which RNA is formed from DNA.
  • Replication occurs in the S-phase of the cell cycle while transcription occurs in G1 and G2 phase of the cell cycle.
  • DNA polymerase is used in replication while RNA polymerase is used in transcription.
  • In replication, two set of DNA is formed from two strands of DNA while in transcription single RNA strand is formed from single strand of DNA.
  • Replication involves copying of the entire genome while transcription involves copying of certain genes only.
  • Replication helps in conserving the genome for generation of cells while transcription forms copies of DNA gene for immediate use in the formation of proteins.

Video Explanation

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