[Biology Class Notes] on Difference Between Replication and Transcription Pdf [2024]

To understand the topic of the Difference Between Replication and Transcription, you need to understand the topic of transcription and replication first. Many times, students tend to get confused in the two processes, thus has tried to bring this topic to you in the easiest way possible. To ensure this, the best subject matter experts of were assigned. Let’s start by understanding the topic of Replication first then followed by transcription.

Replication

DNA replication can be described as the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. This is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, like the parent cell.

The basis of the replication process is the fact that each strand of DNA can serve as a template for duplication. The process initiates at specific points, called the origin of reapplication points, where the DNA double helix is unwound. A short segment of RNA, called a primer, is then synthesised and acts as a starting point for new DNA synthesis. The enzyme DNA polymerase next begins replicating the DNA by matching bases to the original strand. Once DNA synthesis is completed, the RNA primers are replaced with DNA. If there are any gaps between the newly synthesised DNA segments, they are sealed together with enzymes.

DNA replication is a crucial process; therefore, to ensure that mistakes, or mutations, are not introduced, the cell proofreads the newly synthesised DNA. Once the cellular DNA is replicated, the cell can divide into two daughter cells, which would have identical copies of the original DNA.

Transcription

It is a process by which the genetic information contained within DNA is rewritten into a messenger RNA (mRNA) with the help of RNA polymerase. This mRNA then exits the cell nucleus, where it provides the basis for the translation of DNA.

The Stages of Transcription

The process of transcription can be divided into 3 main stages:

Initiation
Elongation
Termination

Initiation

The process is catalysed by the enzyme RNA polymerase. It attaches to DNA and moves along with it until it recognises a promoter sequence, which indicates the starting point of transcription. There may be many promoter sequences in a DNA molecule. Transcription factors are proteins that control the rate of transcription and also bind to the promoter sequences with RNA polymerase.

Once bound to the promoter sequence, RNA polymerase unwinds a portion of the DNA double helix, exposing the bases on each of the two DNA strands.

Elongation

One DNA strand known as the template strand is read in a 3′ to 5′ direction and so provides the template for the new mRNA molecule. The other DNA strand is termed the coding strand because the base sequence of the new mRNA is identical to it, except for the replacement of thiamine bases with uracil.

Incoming ribonucleotides are used by RNA polymerase to form the mRNA strand. It does this using complementary base pairing (A to U, T to A, C to G and G to C). RNA polymerase then catalyses the formation of phosphodiester bonds between adjacent ribonucleotides. Bases can only be added to the 3′ (three-prime) end, so the strand elongates in a 5’ to 3’ direction.

Termination

Elongation will continue until the RNA polymerase encounters a stop sequence. At this point, transcription terminates and the RNA polymerase releases the DNA template.

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In this article, we will learn both similarities and differences between replication and transcription.

Difference Between DNA Replication and Transcription

DNA replication and transcription are two complex biological processes and they have several differences between them. These differences between transcription and DNA replication are mentioned below:

Replication vs Transcription

Character	DNA replication	Transcription
Definition	It is the process of making new copies of DNA.	It is the process by which DNA is copied and transcribed to an RNA.
Significance	It is important for the regulation of the growth and division of cells.	It is the method of regulating gene expression.
Transfer of genetic information	The genetic information is transferred from DNA to DNA.	The genetic information transfers from DNA to RNA.
Occurs during	The S phase of the cell cycle.	Transcription takes place in the G1 and G2 phases of the cell cycle.
Motive	Takes place in preparation for cell division.	It takes place in preparation for protein translation.
Involved in	The process is involved in cell division	The process is involved in gene expression.
Raw materials	The raw materials utilised are dATP, dGTP, dCTP and dTTP.	ATP, GTP, CTP and GTP are the raw materials in this process.
Template	Both DNA strands act as templates.	A single DNA strand acts as a template.
Primers	The process requires an RNA primer to start replication.	No primers are needed to start this process.
Enzymes	The enzymes that are required are DNA polymerase, DNA helicase.	RNA polymerase, transcriptase.
Unwinding and splitting	It involves the unwinding and splitting of the DNA molecule.	Involves the unwinding and splitting of the genes that are to be transcribed.
Base pairing	Adenine pairs with Thymine	Adenine pairs with Uracil
Copying of template	The complete template is copied.	Only a part of the DNA template that codes for required genes are transcribed or copied.
Product	Two daughter molecules of DNA.	mRNA, rRNA, non-coding RNA and tRNA
Strands in product	Double-stranded DNA	Single-stranded RNA
Post-formation	Joining and Okazaki fragments.	RNA editing.
Processing	The DNA molecules that are produced are not needed for processing.	The primary RNA transcript molecule needs processing to acquire the final form.
Bond	The new DNA molecules remain together by hydrogen bonds to the template DNA strand	THE transcribed RNA strand separates from its DNA template strand.
Rate of production	The rate of replication is typically 20 times faster than transcription and six or more replication forks may be present at the same time on the chromosome.	Comparatively slower.

Fun Facts About DNA:

DNA could be stretched from the earth to the sun and back approximately 600 times
Structure of a DNA molecule was discovered by Watson and Crick
Human genome carries 3 billion base pairs of DNA
Study of DNA can link you with people whom you had never imagined
DNA of all creatures are 99.99% alike

Conclusion

Thus we can understand how important the process of DNA replication and transcription is for the sustenance of life. Also, we understood how complicated the processes involved are and what all enzymes and chemicals are involved in the process.

This field of biology is an area where still groundbreaking research work is going on. It is an emerging field that holds a lot of significance in biotechnology and genetics, which has a wide range of applications in medical science and pharmaceutical.

At we understand the importance of this topic, thus we have solutions to previous years biology papers for Class 12. This will help you in scoring good marks in Class 12 board exams.