Describe How Bacteria Decode Its Genetic Information to Produce Proteins?

[4] – Frank Schluenzen et al, Structure of Functionally Active Small Ribosomal Subunit at 3.3A Resolution

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.

3) As a ribosome moves along the mRNA, the genetic message is translated into a protein with a specific amino acid sequence.

After the DNA has been turned into mRNA a process called translation occurs and it turns the mRNA into tRNA.

Then the tRNA molecules link together and transfer the amino acid to the ribosome. An Anticodons pair with a codon takes the

In the case of this lab, the bacteria we use has an inducible operon system in which the protein needed to make the repressor inactive (and turn on protein synthesis) is arabinose. After arabinose makes the repressor inactive, the system can synthesize pGLO protein. Before we added the plasmid to the bacteria, the system normally would have synthesized the enzymes needed to break down arabinose. In terms of pGLO synthesis, it is your normal protein synthesis process. It all starts with RNA polymerase transcribing DNA into a single strand of RNA. RNA Polymerase reads the DNA from 3’ to 5’ end and then lays down RNA nucleotides from 5’ to 3’ end. From there, splicesosomes cut out the introns (noncoding segments in mRNA) and splice together the exons (coding segments in mRNA). After that, the G cap and Poly A Tail are put on to protect the mRNA from getting altered by the enzymes outside of the nucleus. Once RNA processing is finished, the mRNA travels to the Ribosome to get translated into amino acids. Synthetase ha been creating the peptide bonds that attach an amino acid to a tRNA. Once the tRNA is carrying an amino acid, it can enter the accepter chamber of the

c. Draw a square around the translation stop sites in the wild type and the mutant forms of the protein.  (2

This is done by means of the aminoacyl attachment site (the site at which the amino acid is attached to the tRNA molecule). Each tRNA molecule, by means of their anticodons (a sequence of three exposed free bases complimentary to that of the codons on

How frequently the translation of an mRNA is reinitiated, the rate of translation, and mRNA stability are gene-specific control mechanisms that can greatly impact how much protein is produced. These points of control are often regulated by the interaction of specific proteins within the 5’ and 3’ UTRs of mRNA. For example many mRNAs contain specific sequences to which proteins may bind and stabilize, or destabilized the mRNA. Transferrin is a protein receptor that regulates the transport of iron into cells. While cells absolutely require iron to function, too much is toxic. When the intracellular concentration of iron is low, a stabilizing protein binds to a sequence in the 3’ UTR of the transferrin mRNA and stabilizes it. More transferrin

The primary protein structure can be likened to a human chain in which each person is assumed to be an amino acid and their hands viewed as the carboxyl and amino groups. The person on one end of the chain, who has a free left hand, is assumed to be the free carboxyl group. The person on the other end, who has a free right hand, is assumed to be the free amino group. Everyone in this chain has a left hand linked to somebody’s right hand and a right hand linked to somebody else’s left hand forming peptide bonds. The heads and legs just like the side chains and hydrogens, do not take part in the linking.

Deacylated tRNA and mRNA remain bound to the 40S subunit after release of the 60S subunit, and can be released by eIF1, eIF1A, eIF3 and its weakly-associated eIF3j subunit (Pisarev et al., 2007, 2010). The multi-subunit eIF3 binds to the 40S subunit's solvent side, extending from the mRNA entrance to the exit (des Georges et al., 2015), interacting with eIF3j at the former site and with eIF1 at the latter. eIF1 and eIF1A bind to the interface subunit, on the platform adjacent to P-site initiator tRNA and in the A-site, respectively. eIF1 discriminates against non-initiator tRNAs in the P-site (Lomakin et al., 2006) and destabilizes their binding in a manner that it augmented by eIF1A and particularly eIF3 (Pisarev et al., 2010). Release of P-site tRNA leads to dissociation of mRNA in the absence of eIF3 and its partial retention in its presence. eIF3j enhances release of mRNA. At concentrations below 1mM free Mg2+, these factors can recycle post-TCs, eIF3 being primarily responsible for ribosome splitting

Finally, all the nucleotides are joined to form a complete polynucleotide chain using DNA polymerase. The two new DNA molecules form double helices.

The formation of a protein begins in the genes, which contain the basic building information for all parts of living organisms. There are four DNA nucleotides that make up genes: A, T, C, and G. A codon is any arrangement of three of these nucleotides. Each triplet of nucleotides codes for one amino acid. First transcription will begin in the nucleus where mRNA will transcribe the DNA template. During both transcription and translation, there are three steps. The first step in transcription is initiation where RNA polymerase separates a DNA strand and binds RNA nucleotides to the DNA. RNA nucleotides are the same as DNA ones except that U replaces the T. The second is just the elongation of the mRNA. The third step of transcription is termination. This occurs when RNA polymerase reads a codon region and the mRNA separates from the

The three key types of RNA that are involved in protein synthesis are mRNA (messenger RNA), rRNA (ribosomal RNA) and tRNA (transfer RNA). The way I learned to remember the functions of these three is the same way it’s shown on the estrellamountain website. mRNA is like the blueprint of a construction site with its copy of the genetic information of DNA, rRNA is like the construction site where the protein is made, and tRNA is like the delivery truck that brings amino acids to where they need to be at the right time.

Another cellular feature shared by both Archaea and Bacteria is size and arrangement of ribosomes. Their ribosomes are much smaller in comparison to eukaryotes. The function of their ribosomes is similar to the ones in eukaryotes; for translating mRNA codons to sequence of amino acids for the synthesis of proteins. Both have 70S Ribosomes composed of 30S and 50S sub units that are joined to make a 70S unit. They contain “three ribonucleic acid molecules” consisting of “16S, 23S AND 5S”. On the other hand, the “primary structure of Archaea r-RNA and r-Proteins” is much similar to the ones in eukaryotes and less similar to that of bacteria. Additionally, the Archaea ribosome is much firm compared to mesophilic bacteria’s ribosomes, this is particularly beneficial in terms of their adaptation to extreme environmental conditions. (Archaeal Ribosomes, Paola Londei, university of Rome, “Sapienza”