Replication
DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the basis for biological inheritance. Each time a cell divides, the two resulting daughter cells must contain exactly the same genetic information or DNA as the parent cell. For this to be achieved, each strand of existing DNA acts as a template for replication. Usually, replication occurs in three major steps; the opening of the double helix and separation of the DNA strands the priming of the template strand and assembly of the new DNA segment.
Transcription
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA by the enzyme RNA polymerase. Both DNA and RNA are nucleic acids which use base pairs of nucleotides as a complementary language.
Transcription is carried out by enzyme RNA polymerase and a number of accessory proteins known as transcription factors. Together, RNA polymerase and transcription factors forms a complex referred to as transcription initiation complex. This complex initiates transcription and the RNA polymerase begins mRNA synthesis by matching complementary bases to the original strand.
Replication Vs. Transcription: General Differences
Also Read: Difference Between Nucleotide And Nucleoside
Definition
DNA replication produces two exact replicas of the original double-stranded DNA molecule where each daughter strand contains half of the original DNA double helix. Transcription produces a single-stranded RNA molecule using the double-stranded DNA.
Bond
In replication the newly replicated DNA strand remains hydrogen bonded to its template DNA strand while in transcription, the newly transcribed RNA strand separates from its DNA template strand.
Products
During DNA replication the products remain within the nucleus while during transcription, greater part of the product passes from the nucleus into the cytoplasm.
Unwinding and Splitting
Replication involves unwinding and splitting of the entire DNA molecule (chromosome) while Transcription involves unwinding and splitting of only those genes which are to be transcribed.
What it entails
DNA replication involves copying of the entire genome while transcription entails copying of certain individual genes only.
Purpose
DNA replication serves to the genome for the next generation of cells and individuals. On the other hand, transcription serves to form DNA copies of individual genes for immediate use in protein synthesis.
Enzymes
In DNA replication, the two strands are separated and then each strand’s complementary DNA sequence is recreated by an enzyme called DNA polymerase. On the other hand, in transcription, the Codons of a gene are copied into messenger RNA by RNA polymerase. This RNA copy is then decoded by a ribosome that reads the RNA sequence by base-pairing the messenger RNA to transfer RNA which carries amino acid.
Results
In replication the end result is two daughter cells while in transcription, the end result is RNA molecule.
Occurrence
DNA replication occurs in the S phase of the cell cycle, when the cell is preparing for division while transcription occurs in the G1 and G2 phases of cell cycle, when the cell needs to synthesize proteins.
Strand Length
DNA replication synthesizes long DNA strands while transcription synthesizes relatively short strands.
Raw materials
During DNA replication Deoxyribonucleoside triphosphate (dATP, dGTP, dTTP and Dctp serve as raw materials while during transcription Ribonucleoside triphosphate (ATP, UTP, GTP, CTP) serve as raw materials.
End Processing
In DNA replication the newly synthesized DNA are perfectly normal and therefore, undergoes no processing while transcription produces primary RNA transcript molecules which needs processing to acquire final form and size.
Catalyst
DNA replication is catalyzed by enzymes DNA polymerase and DNA Helicase while transcription is catalyzed enzymes transcriptase and RNA polymerase.
Primers
In DNA replication, Enzyme DNA polymerase requires an RNA primer for commencement of the replication. On the other hand, In RNA transcription, enzyme RNA polymerase requires no primers.
Products
Products of DNA replication (two daughter strands) are not degraded while in replication, products (mRNA, tRNA, rRNA and non-coding RNA like micro-RNA) are degraded after their function is over.
Also Read: Difference Between DNA And RNA
Differences Between Replication And Transcription In Tabular Form
| Basis of Comparison | Replication | Transcription |
| Definition | DNA replication produces two exact replicas of the original double-stranded DNA molecule where each daughter strand contains half of the original DNA double helix. | Transcription produces a single-stranded RNA molecule using the double-stranded DNA. |
| Bond | In replication the newly replicated DNA strand remains hydrogen bonded to its template DNA strand. | In transcription, the newly transcribed RNA strand separates from its DNA template strand. |
| Products | During DNA replication the products remain within the nucleus. | During transcription, greater part of the product passes from the nucleus into the cytoplasm. |
| Unwinding and Splitting | Replication involves unwinding and splitting of the entire DNA molecule (chromosome). | Transcription involves unwinding and splitting of only those genes which are to be transcribed. |
| What it entails | DNA replication involves copying of the entire genome. | Transcription entails copying of certain individual genes only. |
| Purpose | DNA replication serves to the genome for the next generation of cells and individuals. | Transcription serves to form DNA copies of individual genes for immediate use in protein synthesis. |
| Enzymes | DNA replication, the two strands are separated and then each strand’s complementary DNA sequence is recreated by an enzyme called DNA polymerase. | In transcription, the Codons of a gene are copied into messenger RNA by RNA polymerase. This RNA copy is then decoded by a ribosome that reads the RNA sequence by base-pairing the messenger RNA to transfer RNA which carries amino acid. |
| Results | In replication the end result is two daughter cells. | In transcription, the end result is RNA molecule. |
| Occurrence | DNA replication occurs in the S phase of the cell cycle, when the cell is preparing for division. | Transcription occurs in the G1 and G2 phases of cell cycle, when the cell needs to synthesize proteins. |
| Strand strength | DNA replication synthesizes long DNA strands. | Transcription synthesizes relatively short strands. |
| Raw materials | During DNA replication Deoxyribonucleoside triphosphate (dATP, dGTP, dTTP and Dctp serve as raw materials. | During transcription Ribonucleoside triphosphate (ATP, UTP, GTP, CTP) serve as raw materials. |
| End Processing | In DNA replication the newly synthesized DNA are perfectly normal and therefore, undergoes no processing. | Transcription produces primary RNA transcript molecules which needs processing to acquire final form and size. |
| Catalyst | DNA replication is catalyzed by enzymes DNA polymerase and DNA Helicase. | Transcription is catalyzed enzymes transcriptase and RNA polymerase. |
| Primers | In DNA replication, Enzyme DNA polymerase requires an RNA primer for commencement of the replication. | In RNA transcription, enzyme RNA polymerase requires no primers. |
| Products | Products of DNA replication (two daughter strands) are not degraded. | In replication, products (mRNA, tRNA, rRNA and non-coding RNA like micro-RNA) are degraded after their function is over. |
Also Read: Difference Between Heterochromatin And Euchromatin
Similarities Between Replication And Transcription
- Both processes use nucleotides as the language on which the daughter strands emerge from.
- Both involves a parent DNA that act as a foundation on which the processes are built on.
- Both have specific proteins that keep the polymerase molecule attached to the parental DNA strand.
- Both have initiation step whereby there is breakage of parental DNA strand.
- Both processes take place in the nucleus.
- Both are processes for protein synthesis in both eukaryotic and prokaryotic cells.
Summary
DNA replication produces two exact replicas of the original double-stranded DNA molecule where each daughter strand contains half of the original DNA double helix. Transcription produces a single-stranded RNA molecule using the double-stranded DNA.