What Is the Difference Between Template and Coding Strand in DNA Transcription
The strand of DNA from which mRNA is formed after transcription is known as the template strand or the antisense strand. The template strand is usually directed 3’ to 5’ in direction. The coding strand or the sense strand corresponds to the same sequence as that of the mRNA strand.
The coding strand is not used as a template and it is reported to have 3 letter codons that code for amino acids. The amino acid sequence is then assembled to form protein. Keeping the similarities aside, the coding strand and the newly synthesized mRNA has a single difference i.e, thymine is present in the coding strand and uracil takes its place in the mRNA strand.
What is Meant by Antisense Strand?
The non-coding DNA strand of a particular gene is known as the antisense strand. The anti-sense strand serves as the template for transcription, which is a process of synthesis of mRNA that occurs in the nucleus of the cell. The mRNA formed then moves from the nucleus to the cytosol where the protein synthesis machinery comes into play and produces protein from the mRNA. This process is called translation. The anti-sense strand is meant by the strand that is complementary to the synthesizing mRNA and sense strand. It is also reported to contain anticodons. The DNA strand that is not used as a template in the transcription process is known as the sense strand.
Difference Between Template Strand and Coding Strand
Template strands and coding strands are discrete strands of the structure of DNA that differ by a few characteristics mentioned below.
Coding and Non-Coding Strand
The strand of DNA whose base sequence is similar to its primary transcript is known as the coding strand or the informational strand. This strand is reported to contain codons.
The non-coding strand or the transcribed strand, on the other hand, contains anticodons. RNA Polymerase II is reported to bind to the non-coding template strand, in the promoter site and reads the anti-codons.
After transcription of the sequence, a newly synthesized RNA transcript is produced with complementary bases. 99% of the DNA is made up of non-coding genes, hence, it was believed that the non-coding genes are junk. Recent studies by scientists proved that this non-coding portion of DNA contains regulatory elements that determine when a gene is turned on and when turned off.
Some regions of non-coding strand of DNA are reported to provide instructions for the synthesis of specialized RNA molecules such as transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), microRNAs (miRNAs), and long noncoding RNAs (lncRNAs), which has significant contribution in the regulation of gene activity.
Non Template Strand
The non-template strand is also known as the coding strand since its sequence is similar to the newly synthesized RNA molecule except for the inclusion of U in place of T. Recent research has shown an important role of the non-template strand specific-signal element of DNA in the terminal transcription bubble. It is believed to help in the process of transcription termination by RNA polymerase III.
Interesting Facts
Non-coding DNA strand is the antisense DNA of a gene that serves as the template for producing messenger RNA. It can make a copy of itself during mRNA synthesis. The coding strand is the DNA strand which cannot act as a template and its base sequence is similar to its primary RNA transcript.
Key Features of Template Strand and Coding Strand
The template strand contains the anti-codons while the coding strand contains the codons.
The polarity of the coding strand is in 3 the’ to 5’ direction, while the non-coding strand is directed in the 5’ to 3’ direction.
Coding DNA contains protein-coding genes and is composed of exons. Non-coding DNA does not code for proteins.
Non-coding DNA was considered junk but recent research has proved its importance in the proper functioning of cell and gene regulation.
FAQs on Difference Between Template and Coding Strand in Transcription
1. What is the difference between template strand and coding strand?
The main difference between the template strand and the coding strand is that the template strand is used by RNA polymerase to synthesize mRNA, while the coding strand has the same sequence as the mRNA (except T is replaced by U).
- The template strand is read in the 3′ → 5′ direction during transcription.
- The coding strand runs 5′ → 3′ and matches the mRNA sequence.
- mRNA is complementary to the template strand.
- Only one strand acts as the template for a particular gene.
2. What is a template strand in DNA?
A template strand is the DNA strand that is directly used by RNA polymerase to synthesize a complementary mRNA molecule during transcription.
- It is also called the antisense strand.
- It is read in the 3′ → 5′ direction.
- The mRNA formed is complementary to this strand.
- It determines the exact sequence of nucleotides in mRNA.
3. What is a coding strand in DNA?
The coding strand is the DNA strand whose nucleotide sequence is similar to the mRNA sequence, except that thymine (T) is replaced by uracil (U) in RNA.
- It is also known as the sense strand.
- It runs in the 5′ → 3′ direction.
- It is not directly used by RNA polymerase during transcription.
- Its sequence represents the genetic code for protein synthesis.
4. Why is only one DNA strand used as a template?
Only one DNA strand is used as a template because transcription requires a single strand to produce a specific and accurate mRNA sequence.
- Using both strands would create two different mRNA sequences.
- Each gene has a defined promoter region that determines which strand is transcribed.
- The orientation of RNA polymerase ensures transcription occurs in one direction.
- This maintains correct gene expression.
5. How does RNA polymerase identify the template strand?
RNA polymerase identifies the template strand by binding to a specific promoter sequence that determines the direction of transcription.
- The promoter has a specific nucleotide sequence.
- Its orientation decides which strand will be read 3′ → 5′.
- Transcription factors assist in recognizing the correct strand in eukaryotes.
- This ensures accurate mRNA synthesis.
6. Is the coding strand the same as mRNA?
The coding strand is almost the same as mRNA because both have identical nucleotide sequences except that DNA contains thymine (T) while mRNA contains uracil (U).
- The coding strand sequence is written 5′ → 3′.
- mRNA replaces T with U.
- The template strand is complementary to both.
- This similarity helps in predicting protein-coding sequences.
7. What are the other names for template and coding strands?
The template strand is also called the antisense strand, while the coding strand is known as the sense strand.
- Template strand = Antisense strand
- Coding strand = Sense strand
- These names refer to their role in transcription.
- The sense strand carries the same sequence as mRNA.
8. In which direction are the template and coding strands read?
The template strand is read in the 3′ → 5′ direction, while the coding strand runs in the 5′ → 3′ direction.
- RNA polymerase moves along the template strand from 3′ → 5′.
- mRNA is synthesized in the 5′ → 3′ direction.
- The coding strand has the same 5′ → 3′ orientation as mRNA.
- This antiparallel arrangement is essential for transcription.
9. Can the template strand change from gene to gene?
Yes, the template strand can change from gene to gene because different genes may be located on opposite DNA strands.
- Some genes use one strand as the template.
- Other genes use the opposite strand.
- The promoter orientation determines which strand is used.
- This allows flexible gene organization in the genome.
10. What is an example of template and coding strand during transcription?
An example of template and coding strands is when a DNA coding strand 5′-ATG CCG TAA-3′ produces an mRNA sequence 5′-AUG CCG UAA-3′.
- The coding strand: 5′-ATG CCG TAA-3′
- The template strand: 3′-TAC GGC ATT-5′
- The mRNA: 5′-AUG CCG UAA-3′
- mRNA is complementary to the template strand and similar to the coding strand.
