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Template Strand and Coding Strand

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What are Template Strand and Coding Strand?

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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.

Serial no.

Features

Template strand

Coding strand

1.

Definition

Forms the base of mRNA transcription.

Determines the nucleotide sequence of mRNA

2.

Other name

Minus strand

Plus strand

3.

Direction of synthesis

5’ to 3’ direction

3’ to 5’ direction

4.

End product

Transcribed into mRNA

Not transcribed into mRNA

5.

Hydrogen Bond formation

Hydrogen Bonds are formed between the newly synthesizing mRNA and the template strand.

No hydrogen bonds are formed between the synthesizing mRNA and the template strand.

6.

Contains codons or anti-codons

Contains anti-codons

Contains codons


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.

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FAQs on Template Strand and Coding Strand

1. What are codons?

In a DNA or RNA, a sequence of three consecutive nucleotides that codes for a specific amino acid or a stop signal is termed codons.

2. What are the properties of genetic code?

The properties of Genetic Code are discussed below-

  • Genetic code is always triplet and non-ambiguous.

  • They are degenerate and non-overlapping.

  • Genetic code is commaless.

  • There is a start codon and a stop codon from where the synthesis of protein begins and ends.

3. What do you mean by transcription?

Transcription is the process of synthesis of mRNA that occurs in the nucleus of a cell. The mRNA is reported to carry the information required for translation. 

4. What is the primary transcript?

The single-stranded ribonucleic acid product of transcription of DNA, is termed as primary transcript. It is further processed with different nucleases and proteins like drosha and dicer to yield mature mRNAs, tRNAs, and rRNAs.


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