What is DNA Replication?
DNA replication, in molecular biology is the biological process by which two identical copies of a DNA molecule are created. As the main part of biological inheritance, DNA replication is an essential component in all living organisms. This is necessary for cell division, growth, and repair of damaged tissue. It also ensures that each new cell receives its own copy DNA. Because cells possess the unique property of division, replication of DNA is essential.
A double helix is made up two complementary strands of DNA. Double helix refers to the appearance of double-stranded DNA. It is composed of two linear, opposite-oriented strands that twist together to form. These strands are separated during replication. Semiconservative replication is a process where each strand of the original DNA molecules serves as a template to make its counterpart. Semi-conservative reproduction results in a new helix that is composed of both an original and a newly synthesized DNA strand. Near perfect DNA replication accuracy is ensured by cellular proofreading and error-checking.
The DNA replication process in a cell begins at certain locations (or origins of replication) within the genome, which contains the genetic material for the organism. The helicase enzyme, which is responsible for unwinding DNA at the origin and the synthesis of new DNA strands, causes replication forks to grow bi-directionally away from the origin. To aid in DNA synthesis’s initiation and progression, a number of proteins are linked to the replication fork. The DNA polymerase is the most important enzyme involved in synthesizing new strands. It does this by adding nucleotides to each template strand. The S-stage of interphase is where DNA replication takes place.
In vitro DNA replication (DNA amplification), can also be done artificially outside of a cell. DNA polymerases can be isolated from cells, and artificial DNA primers may be used to initiate DNA synthesis at sequences known in a template DNA molecular. Polymerase chain reaction (PCR), ligase chain reaction (LCR), and transcription-mediated amplification (TMA) are examples. Researchers reported evidence in March 2021 that a preliminary form transfer RNA, which is a crucial component of translation and the biological synthesis (TMA) of new proteins, might have been an replicator molecule in the very early stages of life development, or abiogenesis.
What is Transcription?
Transcription refers to the process of converting a portion of DNA into RNA. Messenger RNA (mRNA) is produced when DNA segments are transcribed into RNA molecules capable of encoding proteins. Some segments of DNA can also be copied into RNA molecules known as non-codingRNAs (ncRNAs). The average mRNA quantity is greater than 10 times that of the ncRNA when it is spread across multiple cells in a tissue. However, in some cases ncRNAs can be more abundant than mRNAs in single cell types. The preponderance or mRNA is true even though less than 2 percent of the human genome can transcribe into mRNA. However, at least 80% can be active transcribed in one or more cells.
Both DNA andRNA are nucleic acid, which use base pairs nucleotides to create a complementary language. An RNA polymerase reads a DNA sequence and produces an antiparallel, complementary RNA strand, called a primary transcript.
The following steps are used to transcribe:
- Together with one or more general transcription factor(s), RNA polymerase binds to promoter genome.
- The transcription bubble is created by RNA polymerase, which splits the DNA helix into two distinct strands. This is achieved by breaking hydrogen bonds between DNA nucleotides.
- RNA polymerase also adds RNA nucleotides, which are complementary to nucleotides from one DNA strand.
- With the help of RNA polymerase, a RNA sugar-phosphate backbone is formed to form anRNA strand.
- The RNA-DNA helix hydrogen bonds break, allowing the newly synthesized RNA strand to be freed.
- The RNA can be further processed if the cell contains a nucleus. This could include polyadenylation and capping.
- The RNA can either remain in the nucleus, or it may exit the cytoplasm via the nuclear pore complex.
The RNA that is transcribed into an RNA molecule encodes a protein is called messenger RNA (mRNA). The mRNA serves as a template to the protein’s formation through translation. Other DNA stretches can be transscribed into smaller non-codingRNAs, such as microRNA or transfer RNA(tRNA), small nucleolarRNA (snoRNA), and small nuclearRNA (snRNA). Enzymatic RNA molecules known as ribozymes may also be used to translate larger non-codingRNAs like ribosomalRNA (rRNA) and long noncodingRNA (lncRNA). RNA is essential for the function of a cell. It regulates, synthesizes, and processes proteins.
The term transcription is also used in virology to refer to mRNA synthesizing from an RNA molecular (i.e. equivalent to RNA replication). The genome of a single-stranded single-sense RNA virus (ssRNA–) may serve as a template for a single-stranded positive-sense RNA (+) [clarification required]. Because the positive-sense sequence information contains the sequence information necessary to translate the viral proteins required for viral replication, this is possible. A viral RNA replicase catalyzes this process.
Differences between DNA Replication and Transcription – DNA Replication vs Transcription
|Definition||DNA replication refers to the creation of new DNA copies.||Transcription refers to the process of copying DNA (transcription) into RNA.|
|Significance||For proper regulation of cell growth and division, DNA replication is essential.||Transcription is the process of regulating gene expression.|
|Transfer of genetic information||From DNA to DNA||From DNA toRNA|
|Occurs during||Phase S of the cell cycle.||It occurs in the G1 or G2 phases of the cell cycle.|
|Motive||Preparation for cell division.||Preparation for protein translation|
|Participate in||Cell division||Gene expression|
|Raw Materials||As raw materials, dATP, dGTP and dTTP are available.||Raw materials include ATP, UTP (GTP), CTP and GTP.|
|Template||Both DNA strands||One DNA strand|
|Primers||To start replication, you will need an RNA primer||For initiation, no primer is necessary.|
|Enzymes Required||DNA Helicase, DNA Polymerase||Transcriptase, RNA polymerase (type of DNA Helicase).|
|Unwinding and Parting||This involves the unwinding and splitting of all DNA molecules.||This involves unwinding and splitting only the genes that are to be transcribed.|
|Base pairing||Adenine and thymine go together||Adenine is paired with uracil, not thymine.|
|Copy of Template||Copy the entire template strand.||Only the part of the template DNA that codes the required genes is transcribed or copied.|
|Product||Two daughters DNA||mRNA, microRNA, and tRNA.|
|Strands in product||DNA double-stranded||Single-stranded RNA|
|Post-formation||Okazaki fragments joined||Editing RNA|
|Processing||It creates normal DNA molecules, which do not require any processing.||It generates primary RNA transcript molecules, which need to be processed in order to attain final form and size.|
|Bond||The hydrogen bond between the template DNA strand and the replicated DNA strand is still in place.||The transcribed RNA strand is separated from its DNA template.|
|Migration from the place of formation||Products are still within the nucleus.||A greater percentage of the product is transferred from the nucleus to the cytoplasm.|
|Degradation of product formed||Products do not get degraded.||After their function is complete, products are considered to be degraded.|
|Production Rate||Replication is usually 20 times faster than transcription. Six or more replication forks can be present simultaneously on the chromosome.||Comparatively, it is slower|
|The process is followed||Transcription/Next replication||Translation. Some RNA can be the final product.|
|Significance||Keep the whole genome safe for the next generation.||Protein synthesis requires it.|