Messenger RNA (A-level Biology)

Messenger RNA

Protein Synthesis and mRNA

Structure of mRNA

  • mRNA is single stranded. This single-stranded RNA consists of nucleotides with the bases U, A, C, and G.
  • Bases are arranged in codons. Similar to bases in DNA, the bases in mRNA are arranged in groups of three, known as codons.
  • Nucleotides consist of three parts. Again, similar to DNA, the nucleotides that form mRNA are made up of a base, a phosphate group and pentose sugar called ribose. 
  • mRNA has a sugar-phosphate backbone. Each of the nucleotides in mRNA are attached through phosphodiester bonds between the phosphate and ribose groups. This forms a sugar-phosphate backbone.
  • mRNA is directly transcribed from DNA. Enzyme RNA polymerase II directly transcribes mRNA. The mRNA is complementary to the gene sequence from which it was made.


A-level Biology - Messenger RNA
A-level Biology – Messenger RNA

Role of mRNA

  • There are many types of RNA in a cell. messenger RNA (mRNA) is  one of the most important types of RNA, despite only accounting for 10% of the total RNA content of a cell.
  • mRA carries information to ribosomes. RNA is the messenger which carries the genetic sequence necessary to make proteins to the ribosomes.
  • mRNA is found in the nucleus. mRNA is produced in the nucleus, during the process of transcription. We will cover more about this later.
  • Hydrogen bonds must break to form mRNA. During the process of transcription, hydrogen bonds between 2 strands of DNA in the double helix are broken. This leads to the creation of a template strand from which mRNA can be produced.
→What is Messenger RNA (mRNA)?

Messenger RNA (mRNA) is a type of RNA molecule that carries the genetic information from DNA to the ribosome, where it is used to make proteins. The mRNA molecule is synthesized from a DNA template in a process called transcription and serves as the intermediate between the genetic information stored in DNA and the functional proteins produced in cells.

→What is the role of mRNA in protein synthesis?

The role of mRNA in protein synthesis is to deliver the genetic information from DNA to the ribosome, where it is translated into a protein. The ribosome reads the codons, or sequences of three nucleotides, on the mRNA molecule and matches them to the corresponding amino acids to build the protein.

→How is mRNA synthesized from DNA?

mRNA is synthesized from DNA by a process called transcription. This process is initiated when an enzyme called RNA polymerase binds to a specific DNA sequence, or promoter, and begins to make a complementary RNA copy of the DNA template. The mRNA molecule is then modified by the addition of a 5′ cap and a poly(A) tail, which help to stabilize and protect the molecule during translation.

→How does mRNA differ from other types of RNA?

mRNA differs from other types of RNA in several ways. mRNA is the largest and most complex type of RNA, and it is the only type of RNA that is directly involved in protein synthesis. Other types of RNA, such as transfer RNA (tRNA) and ribosomal RNA (rRNA), have different functions and structures, and they play important roles in the process of protein synthesis.

→Can mRNA be edited or modified?

Yes, mRNA can be edited or modified after it is synthesized from DNA. This process, called mRNA processing, involves the addition or removal of nucleotides from the mRNA molecule, which can change the sequence of codons and alter the protein that is produced. Some examples of mRNA modifications include alternative splicing, where different parts of the mRNA molecule can be combined in different ways to produce multiple protein variants, and post-transcriptional modification, where chemical groups are added to the mRNA molecule to alter its function.

→How does mRNA help to regulate gene expression?

mRNA helps to regulate gene expression by controlling the amount of protein that is produced from a given gene. The level of mRNA produced from a gene can be regulated by several factors, including the rate of transcription, the stability of the mRNA molecule, and the efficiency of translation. In this way, mRNA acts as a critical link between the genetic information stored in DNA and the functional proteins produced in cells.

→How can mRNA be used in biotechnology and medicine?

mRNA can be used in biotechnology and medicine in several ways. For example, mRNA can be used as a therapeutic tool to treat genetic diseases, by delivering functional mRNA to cells that are missing a functional gene. mRNA can also be used as a tool for vaccine development, by encoding for antigens that stimulate the immune system to produce protective antibodies.

→What are some current challenges and limitations in the study of mRNA?

Some of the current challenges and limitations in the study of mRNA include the complexity of mRNA regulation, the difficulties in measuring mRNA levels and protein production, and the lack of efficient methods for delivering mRNA to cells. Despite these challenges, ongoing research in this field is providing new insights into the role of mRNA in gene expression and cellular function, and is helping to advance our understanding of biological processes.

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