Ribozymes are catalytic molecules that cleave the ribonucleic acid (RNA) at specific sequences (Gesteland et al. 2006). RNA is the nucleic acid that is made in the process of transcription; when the deoxyribonucleic acid (DNA) anneals, it transcribes itself into a linear stranded molecule called RNA. In order for RNA to synthesise proteins, it requires catalytic enzymes to perform certain chemical reactions. In the past, it was thought that all chemical reactions are catalysed by protein enzymes; however, in the eighties this hypothesis was disproved as Thomas Cech and Sydney Altman discovered that RNA is able to carry out self-catalysing activities which were named as ribozymes because they perform similar functions as the protein enzymes (Jaeger, 1997). Even though, RNA ribozymes lack the functional groups diversity found in protein enzymes, they are able to carry out their own catalytic reactions due to their tendency to fold into a 3D structure and form helices by Watson-Crick base pairing role (Kiehntopf et al. 1995). Ribozymes are now play critical role in the understanding of biochemistry, as they have the ability to catalyse some of the most important chemical reactions such as RNA splicing as well as the synthesis of peptides, for instance ribozymes can speed up the phosphoryl transfer chemical reactions by 1011 folds. This review will describe the structure, sources and applications of ribozymes.
There are several naturally occurring ribozymes that have been identified to date; these are divided into three distinct classes. Firstly, the self splicing introns that fall into groups I and II respectively depending on their structure and the recognition sequences. Self splicing group I intron was the first ribozyme to b...
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...the cells, the localisation of the ribozymes in the cells as well as the selection site of the messengerRNA (James and Gibson, 1998).
Ribozymes are currently considered to hold many promises for the future development of gene therapy as they have the ability to splice and cleave any target RNA sequences. There are seven natural ribozymes known and several artificial ribozymes have been created. These artificial ribozymes are being used as therapeutic agent to target the aberrant gene expression in many lethal diseases such as cancer. The limitation of artificial ribozymes is mainly due to the difficulty in their delivery to the target cells. Therefore, more research needs to be conducted in thoroughly studying the organisation and structures of the natural RNA ribozymes to achieve successful artificial ribozymes that have complex function in the future.
In order to do this a polymer of DNA “unzips” into its two strands, a coding strand (left strand) and a template strand (right strand). Nucleotides of a molecule known as mRNA (messenger RNA) then temporarily bonds to the template strand and join together in the same way as nucleotides of DNA. Messenger RNA has a similar structure to that of DNA only it is single stranded. Like DNA, mRNA is made up of nucleotides again consisting of a phosphate, a sugar, and an organic nitrogenous base. However, unlike in DNA, the sugar in a nucleotide of mRNA is different (Ribose) and the nitrogenous base Thymine is replaced by a new base found in RNA known as Uracil (U)3b and like Thymine can only bond to its complimentary base Adenine. As a result of how it bonds to the DNA’s template strand, the mRNA strand formed is almost identical to the coding strand of DNA apart from these
This article relates to this course about Biology within the cells. This article relates to
Alternative splicing facilitates the development of HCC either by generating oncogenic variants or by inactivating the tumor suppressors. For example, an alternative POLDIP3 transcript promotes hepatocellular carcinoma progression (18). POLDIP3 is a target of ribosomal protein S6 kinase 1, and regulates DNA replication and mRNA translation. The alternative POLDIP3 transcript (POLDIP3-β), which lacks exon 3 and 29 amino acids, was found to be significantly up-regulated in clinical hepatocellular carcinoma (HCC) tissues compared to paired adjacent noncancerous hepatic tissues. This POLDIP3-β isoform has been shown to increase HCC cell proliferation, inhibit HCC cell apoptosis, enhance HCC cell migration, and promote xenograft growth. Another example is the cell fate determinant protein, Numb, which is aberrantly spliced in HCC and promotes proliferation and invasion (19).
8. Becker W. M, Hardin J, Kleinsmith L.J an Bertoni G (2010) Becker’s World of the Cell, 8th edition, San Francisco, Pearson Education Inc- Accessed 23/11/2013.
"The Species of the Secondary Protein Structure. Virtual Chembook - Elmhurst College. Retrieved July 25, 2008, from http://www.cd http://www.elmhurst.edu/chm/vchembook/566secprotein.html Silk Road Foundation. n.d. - n.d. - n.d.
So now we have an RNA strand. From this strand the protein will be synthesized, this is called translation (RNA is translated into protein). A protein is made from amino acids; these form a strand. I show the protein strand as a linear line, but in reality complex interactions between amino acids lead to 3 dimensional forms that are essential for the functioning of the protein. The translation of RNA to protein is different than the synthesis of RNA from DNA (transcription). When the DNA was transcribed into RNA, one base of DNA corresponded to one base of RNA, this 1 to 1 relation is not used in the translation to protein. During this translation, 1 amino acid is added to the protein strand for every 3 bases in the RNA. So a RNA sequence of 48 bases codes for a protein strand
Fibrous and Globular Proteins Proteins are necessary for function of nearly all forms of life on this earth. They consist of one or several long chains (polypeptides) of amino acids linked in a characteristic sequence. This sequence is called the primary structure of the protein. These polypeptides may undergo coiling to for an alpha helix, or pleating to forma beta pleated sheet, the nature and extent of which is described as the secondary structure. The three-dimensional shape of the coiled or pleated polypeptides is called the tertiary structure.
Enzymes are molecules, specifically proteins that catalyze chemical reactions. Enzymes, like all catalysts, accelerate the rate of a reaction by lowering the activation energy. Nucleic acid RNA molecules called ribozymes can also act as enzymes and catalyze reactions. The development of new enzymes for the synthesis of chemical reactions, pharmaceuticals, and tools for molecular biology is a new and upcoming interest. Work has previously been done in the development for modifying and improving already existing enzymes. There is also much to still learn involving the designs and evolution of enzymes because it is greatly reliant on extensive knowledge of the mechanisms of these reactions. In this paper it is shown that new enzymatic activities can be created de novo, which means from scratch or very differently. There is no need for previous mechanistic information. This is done by selecting from a naive protein library, or one in which it is not designed to do what they are actually doing with it. This library is made up of a trillion different proteins with different amino acid sequences, so there is not much need for a plan. Messenger RNA, RNA used specifically to translate proteins, display is used and the proteins are covalently linked to their encoding mRNA, meaning that they share stable chemical bonds and are tethered to each other. Functional proteins are selected from an in vitro translated protein library. This is not an obvious way to link the genetic information that encodes it together. It is done without constraints imposed by any in vivo step, which simplifies the process when it is in vitro. This specific technique has been used to evolve short or small proteins called peptides as well as specific prote...
Cain, M. L., Urry, L. A., & Reece, J. B. (2010). Campbell Biology. Benjamin Cummings.
The. San Francisco: Benjamin Cummings, 2002. Print. The. The "Epigenetics" of the "Epigenetic PBS. PBS, 09 Jan. 2000.
Allozymes are characterized as the single locus allelic variants of protein representing as the expressed gene product. It exist in a polymorphic form, thus act as a type I markers. Since the early days of molecular genetics, starch gel electrophoresis of allozymes has been considered as the most important and significant method in animal science [43]. The changes in the DNA sequence will be reflected in the form of amino acid differences in the polypeptide chains of the different allozymes allelic form produced by starch gel electrophoresis. Depending on the nature
...cture. Regions 3 and 4 are also complementary and can form this same structure. Which of the two structures form is dependent on the level of trp in the environment. If trp is abundant, then as the ribosome translates over region 1, charged tRNA-trp will arrive at the codon site allowing for fast translation and quick arrival and partial overlap of region 2 making it unavailable to associate with region 3. Region 3 then associates with region 4 signaling for termination and for RNA polymerase to disassociate from the DNA before it transcribes the structural genes. When the environment is starved of tryptophan, as the ribosome translates over region 1, the ribosome stalls as it waits for charged tRNA-trp. This delay allows for the association of region 2 with region 3 preventing the pairing of regions 3 and 4 and permitting the transcription of the structural genes.
Distinct characteristics are not only an end result of the DNA sequence but also of the cell’s internal system of expression orchestrated by different proteins and RNAs present at a given time. DNA encodes for many possible characteristics, but different types of RNA aided by specialized proteins sometimes with external signals express the needed genes. Control of gene expression is of vital importance for an eukaryote’s survival such as the ability of switching genes on/off in accordance with the changes in the environment (Campbell and Reece, 2008). Of a cell’s entire genome, only 15% will be expressed, and in multicellular organisms the genes active will vary according to their specialization. (Fletcher, Ivor & Winter, 2007).
In these techniques mRNA is a key component to understanding