Ribosomal ribonucleic acid, or rRNA, is the principle component of the ribosome and is crucial in the development of proteins for living cells. Approximately 80-85% of a cell’s total RNA is made up of rRNA. The low molecular weight transfer RNA (tRNA), which aids in bringing amino acids to the site of ribosomal translation, comprises only 15-20%. The remaining 1-5% is made up by messenger RNA (mRNA), which is essentially the encoding blueprint for the synthesis of a given protein.
Proteins are comprised of particularly assembled amino acid chains – the instructions for proper sequencing of these chains are found within the cell’s genome. Transcription of the DNA into RNA is the first step towards protein production. This occurs in the nucleus of the cell and undergoes RNA splicing to produce mRNA (Transcription, 2014). In addition to the removal of introns, mature mRNA will also exhibit the addition of a 5’ cap and a 3’ poly(A)-tail. This cap provides resistance to 5’ exonuclease activity and protects the mRNA from degradation on that end. The cap also serves as an important binding site for ribosomes during translation, and aids the transport of mRNA through the nuclear membrane into the cytoplasm. Similar to the 5’ cap, the poly(A)-tail also helps prevents degradation of the mRNA and may help facilitate the movement of mRNA into the cytoplasm.
Translation of the newly synthesized mRNA occurs in the cytoplasm, through coordination of the ribosome and other
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Transcription is the formation of an RNA strand from a DNA template within the nucleus of a cell. There are four nucleotides of DNA. These are adenine, cytosine, guanine and thymine. These nucleotides are transcribed to form messenger ribonucleic acid (mRNA) consisting of nucleotides made of adenine, cytosine, guanine and uracil. This transcription from DNA to mRNA happens by an RNA polymerase II. This newly created mRNA is read in the 5' to 3' direction in sets of 3. These sets are called codons. Each mRNA also has a cap and end. On the 5 prime side is a methylated guanine triphosphate and on the 3 prime is a poly A tail. Messenger RNA then moves to the cells cytoplasm and through the cells ribosomes for translation. Messenger RNA is matched to molecules of transfer RNA (tRNA) in the ribosomes to create amino acids. These amino acids subsequently form an amino acid chain. (Osuri, 2003) A visual representation of this can been viewed in figure 3.
Translation is a task that makes ribosomes synthesize proteins utilizing mRNA transcript made during transcription. In the begining of this task mRNA attaches it self to a ribosome so that it can be reveal a codon (three nucleotides).
The virus fuses with the cell’s plasma membrane. The capsid proteins are removed, releasing the viral proteins and RNA. Reverse transcriptase catalyzes the synthesis of a DNA strand complementary to the viral RNA. Reverse transcriptase catalyzes the synthesis of a second DNA strand complementary to the first. The double-stranded DNA is incorporated as a provirus into the cell’s DNA. Proviral genes are transcribed into RNA molecules, which serve as genomes for the next viral generation and as mRNAs for translation into viral proteins. The viral proteins include capsid proteins and reverse transcriptase (made in the cytosol) and envelope glycoproteins (made in the ER). Vesicles transport the glycoproteins from the ER to the cell’s plasma membrane. Capsids are assembled around viral genomes and reverse transcriptase molecules. New viruses bud off from the host cell.
The process of gene expression is used by all known life known as eukaryotes which include multicellular organisms, prokaryotes like bacteria and Achaea, and viruses which generates the macromolecular machinery for life. Gene expression is what “turns on” the genes and makes a product. The products made could be an enzyme, a protein, or a control molecule. These products are often proteins, but in non-protein coding genes such as mRNA genes or tRNA genes, the product is a functional RNA. The order of gene expression is transcription, RNA processing, then translation. The control of transcription: this is the first step of gene expression when a particular segment of DNA is copied into RNA by the enzyme RNA polymerase and is then a joined mechanism. During transcription, a DNA sequence is read by an RNA polymerase, which produces a corresponding, antiparallel RNA strand called a primary transcript. The order that transcription goes in would start with the initiate transcription from a gene by binding the RNA polymerase to the promoter DNA. A promoter is a region of DNA that initiates transcription of a particular gene. The RNA polymerase then splits the double helix DNA molecule into two nucleotides. When doing this the breaking down of the hydrogen bonds between DNA nucleotides occurs. The RNA and DNA helix’s break apart and the new RNA strand is complete. If the cell has a nucleus, it will then be processed again which will then exits to the cytoplasm. During this process a
5. The MRNA strand detaches from the DNA and moves out of the nucleus into the cytoplasm. 6. The mRNA passes through a ribosome when it passes through each bases causes an amino acid to be attached to a particular protein that is made in the Ribosome. Which is then translated to a correct sequence of amino acids at a ribosome.
This is my first analogy post, so please bear with me. I thought it might be helpful to further describe the process of coupled Transcription-Translation, as there seemed to be confusion during our last lecture.
When the mRNA arrives at the ribosome, the mRNA will connect to the end of it. From here the information on the mRNA will be read. On the mRNA are codons, a set of three nitrogenous bases in DNA or mRNA, these codons are what is being read. When the placement of codons has been looked over, the transfer RNA (tRNA) is activated and begins to match each codon with an anticodon that is in the tRNA. Together the codon and the anticodon create amino acids that are joined by peptide bonds, these amino acids are the building blocks of
Most genes contain the information needed to make functional molecules called protein. The protein synthesis begins with the transcription of DNA into messenger RNA in the nucleus. After transcription, the mRNA reaches the ribosome where its code is translated into amino acids. A chain of these amino acid known as the polypeptide chain, which then forms a folded protein. A single gene can produce mRNA which then can be used to make many different proteins. In gene knockdown the translation step is been
The RNA copy (messenger RNA) of the protein genetic information encoded in DNA molecule is produced in the nucleus. Each mRNA encodes the information for a single protein. They are single strands of nucleotides created during the process of transcription, which acts as a messenger that carries codes from the DNA in the nucleus to the cytoplasm. The mRNA molecules exit the nucleus through tiny openings called nuclear pores. In the cytoplasm, the protein polymers are synthesised through chemical reactions and this helps to enable the actual protein synthesis. Once it exits the nucleus and enters the cytoplasm, the mRNA can interact with the ribosome, which is the cell’s assembler within the process of protein synthesis. The ribosome is made up
The mRNA nucleotide triplets are called codons, and are written in the 5' to 3' direction. The denotation of the word codon is also used for the DNA nucleotide triplets along the non-template strands. These codons are complementary to the template strand in which it is identical to the mRNA, except they have a T instead of U. During translation, codons along an mRNA molecule is translated one of the 20 amino acids making up that polypeptide chains. The codons are read by translation in the 5' to 3' direction along mRNA. Each codon specifies one of the 20 amino acids that will be bonded at the corresponding position along a
c. Messenger RNA is a single-stranded RNA molecule that carries the instructions from a gene inside of the nucleus that is always strand number 1 to make a protein. The transfer RNA transfers amino acids to the ribosome to make the protein.