The difference between template and coding strand is mainly due to the following properties: directional polarity and function. Both template and coding strand are the two distinct strand of the double-stranded DNA, in which the former works as a base to transcribe mRNA, and the latter determines the correct base sequence of the mRNA.
Directional Polarity: The template strand moves from the 3’end to the 5’ end, whereas the coding strand moves opposite to the direction of the template strand, i.e. from 5’end to 3’ end.
Base Sequence: The template strand’s base sequence is complementary to both the coding strand and the mRNA strand. Conversely, the coding strand’s base sequence is as similar to the new mRNA strand except for one change (uracil replaces the thymine).
In this session, we will primarily focus on the key differences between the template and coding strand along with the comparison chart. In addition to this, you will get to know the definition and examples of the two.
Content: Template Vs Coding Strand
Comparison Chart
| Properties | Template strand | Coding strand |
|---|---|---|
| Alternative names | Antisense, Minus or Non-coding strand | Sense, Plus or Non-template strand |
| Function | Acts as the template for the RNA synthesis | Determines the sequences of the RNA strand |
| Directional polarity | Moves in a 3’-5’ direction | Moves in a 5’-3’ direction |
| Reading by RNA polymerase | RNA polymerase reads the template strand from 3’ to 5’ end | RNA polymerase do not read the coding strand |
| Nucleotide base sequence | Its base sequence is complementary to the both coding strand and the mRNA | Its base sequence is same as the newly formed mRNA, but uracil replaces thymine |
| Genetic coding | Template strand have “Anticodons” | Coding strand have “Codons” |
| Formation of Hydrogen bond | Hydrogen bond forms temporarily between the template strand and the newly synthesizing mRNA at the time of transcription | No such bond forms |
Definition of Template Strand
The template strand is one of the DNA strands whose base sequence helps in building mRNA through complementary base sequencing. Template strand or “Antisense strand” runs in 3’- 5’ direction, opposite to the coding strand. It contains complementary nucleotide sequences to the transcribed mRNA.
After transcription, the mRNA before converted into mature mRNA, it undergoes certain post-transcriptional modifications. The template strand also contains “Anticodons” that carry triplet codes or triplet nucleotide sequences complementary to the anticodon sequence of the t-RNA.
The anticoding helps in the attachment of the specific amino acid to the t-RNA to form protein or a peptide chain via the assistance of rRNA. An RNA polymerase reads the template strand to make an RNA transcript by recognizing the promoter genes or sequences. Hence, RNA polymerase is the one which decides the initiation of transcription and termination of the translation process.
Example
Suppose, the template strand carries 5’- A T C G C G T A – 3’ gene sequence. The RNAP will first bind to the promoter region of the DNA sequence and promote transcription. By the attachment of RNAP with the promoter site, the template strand will transcribe to form the primary mRNA transcript.
As we have discussed the mRNA will form complementary base sequences to that of the template strand. Therefore, mRNA will carry 3’- U A G C G C A U – 5’ base sequence.
Definition of Coding Strand
It is one of the DNA strands with a quadrate base sequence with the primary mRNA or the transcribed mRNA. The base sequence of mRNA similar to the coding strand, will have the same nucleotide bases, except for thymine. In mRNA, uracil is the nitrogenous base that replaces thymine.
Coding or “Sense strand” runs in a 5’- 3’ direction, opposite to the template strand. As the RNAP uses the template strand to transcribe the mRNA, the other strand will be the sense strand that will form a complementary strand to that of the template. It contains triplet codons, which code for the specific amino acid to build proteins through the mRNA translation.
Example
Suppose, the template strand carries 5’- A T C G C G T A – 3’ gene sequence. The coding strand will produce complementary pairs relative to the template strand according to the Watson and Crick model.
Therefore, the sense strand’s base sequence will be 3’- T A G C G C A T – 5’. The RNAP will bind to the promoter region of the DNA sequence and promotes the process of transcription.
By the attachment of RNAP with the promoter site, the template strand will transcribe to form the primary transcript with a base sequence 3’- U A G C G C A U – 5’.
Key Differences Between Template and Coding Strand
- Minus, antisense and non-coding strand are the alternative names for the template strand, whereas plus, sense and non-template strand are the alternative names for the coding strand.
- Template strand functions as a base for the RNA synthesis. The coding strand functions to determine the correct nucleotide base sequence of the RNA strand.
- The direction of the template strand is in 3’ to 5’, whereas the coding strand shows opposite directional polarity, i.e. 5’ to 3’ direction.
- The RNA polymerase reads the non-coding or template strand from the 3’-5’ direction and polymerizes the RNA transcript by adding complementary nucleotides relative to the template strand.
- The nucleotide base sequence of the template strand (3’-5’) is complementary to the base sequence of both the sense strand and the mRNA transcript (5’-3’).
- The antisense strand consists of tRNA anticodons, whereas the sense strand includes codons that code the specific amino acid to form a peptide chain.
- Hydrogen bond temporarily forms between the template strand and the newly synthesized mRNA at the transcription time, whereas the coding strand does not establish such type of bond with the mRNA.
Conclusion
Both the sense and antisense strand of DNA coordinates to transcribe RNA and further translate proteins. Sometimes, the two strands of the DNA is called Watson and Crick strand, named after the two scientists Watson and Crick who gave the model of double-stranded DNA.