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#151
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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior Dallas |
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#152
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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior Dallas |
#153
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He's trying so hard to tiptoe around the subject and ease the vaccine point in without offending his constituents' feelings. The point does get lost when you do not have the conviction to sell a product you believe in. A product he helped create, no less. Sure glad Biden didn't have Trump's baggage and can sell the vaccine without holding back. Any participant coming out of that rally is leaving with a mixed message from his/ her leader. I should take it because Trump took it. But wait, he said it's my freedom NOT to take it. So no, I don't necessarily have to take it. That's a pretty botched job of vaccine endoresment, it's almost painful to watch.
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2003 X5 4.6is Estoril Blue, acquired March 2018 2013 128i M Sport 6 MT Space Grey daily driver 2010 535xi 6 MT Barbera Red |
#154
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I like your optimistic outlook. Some are now up to 4 jabs, per CDC. Something has to give, at least that is what I hope and pray for.
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02 BMW 5 Speed Supercharged Ethanol Burnin Meth Injected E53 |
#155
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You are that unwilling knight in King Arthur's cicle of knights, who didn't believe he's found a king worthy of his sword when he first met King Arthur. https://www.youtube.com/watch?v=Af-N8CLLoqU Step up and endorse the vaccine. You took it, your whole family took it, what's so hard about singing it's praises? Stay positive and know that there's more of us who also believe in it.
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2003 X5 4.6is Estoril Blue, acquired March 2018 2013 128i M Sport 6 MT Space Grey daily driver 2010 535xi 6 MT Barbera Red |
#156
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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior Dallas |
#157
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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior Dallas |
#158
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Thanks. If Covid vaccine is King Arthur, then BC you are Lancelot, its greatest champion.
Good thing we do not have a Guinevere in this analogy or it'll backfire spectacularly.
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2003 X5 4.6is Estoril Blue, acquired March 2018 2013 128i M Sport 6 MT Space Grey daily driver 2010 535xi 6 MT Barbera Red |
#159
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Messenger RNA (mRNA) Messenger RNA (mRNA) is a single-stranded RNA molecule that is complementary to one of the DNA strands of a gene. The mRNA is an RNA version of the gene that leaves the cell nucleus and moves to the cytoplasm where proteins are made. During protein synthesis, an organelle called a ribosome moves along the mRNA, reads its base sequence, and uses the genetic code to translate each three-base triplet, or codon, into its corresponding amino acid. Narration Messenger RNAs, also known as mRNA, are one of the types of RNA that are found in the cell. This particular one, like most RNAs, are made in the nucleus and then exported to the cytoplasm where the translation machinery, the machinery that actually makes proteins, binds to these mRNA molecules and reads the code on the mRNA to make a specific protein. So in general, one gene, the DNA for one gene, can be transcribed into an mRNA molecule that will end up making one specific protein. Lawrence C. Brody, Ph.D. https://www.genome.gov/genetics-glossary/messenger-rna The Three Roles of RNA in Protein Synthesis Although DNA stores the information for protein synthesis and RNA carries out the instructions encoded in DNA, most biological activities are carried out by proteins. The accurate synthesis of proteins thus is critical to the proper functioning of cells and organisms. We saw in Chapter 3 that the linear order of amino acids in each protein determines its three-dimensional structure and activity. For this reason, assembly of amino acids in their correct order, as encoded in DNA, is the key to production of functional proteins. Three kinds of RNA molecules perform different but cooperative functions in protein synthesis (Figure 4-20): Figure 4-20. The three roles of RNA in protein synthesis. Figure 4-20 The three roles of RNA in protein synthesis. Messenger RNA (mRNA) is translated into protein by the joint action of transfer RNA (tRNA) and the ribosome, which is composed of numerous proteins and two major ribosomal RNA (rRNA) molecules. [Adapted from (more...) 1. Messenger RNA (mRNA) carries the genetic information copied from DNA in the form of a series of three-base code “words,” each of which specifies a particular amino acid. 2. Transfer RNA (tRNA) is the key to deciphering the code words in mRNA. Each type of amino acid has its own type of tRNA, which binds it and carries it to the growing end of a polypeptide chain if the next code word on mRNA calls for it. The correct tRNA with its attached amino acid is selected at each step because each specific tRNA molecule contains a three-base sequence that can base-pair with its complementary code word in the mRNA. 3. Ribosomal RNA (rRNA) associates with a set of proteins to form ribosomes. These complex structures, which physically move along an mRNA molecule, catalyze the assembly of amino acids into protein chains. They also bind tRNAs and various accessory molecules necessary for protein synthesis. Ribosomes are composed of a large and small subunit, each of which contains its own rRNA molecule or molecules. Translation is the whole process by which the base sequence of an mRNA is used to order and to join the amino acids in a protein. The three types of RNA participate in this essential protein-synthesizing pathway in all cells; in fact, the development of the three distinct functions of RNA was probably the molecular key to the origin of life. How each RNA carries out its specific task is discussed in this section, while the biochemical events in protein synthesis and the required protein factors are described in the final section of the chapter. Go to: Messenger RNA Carries Information from DNA in a Three-Letter Genetic Code RNA contains ribonucleotides of adenine, cytidine, guanine, and uracil; DNA contains deoxyribonucleotides of adenine, cytidine, guanine, and thymine. Because 4 nucleotides, taken individually, could represent only 4 of the 20 possible amino acids in coding the linear arrangement in proteins, a group of nucleotides is required to represent each amino acid. The code employed must be capable of specifying at least 20 words (i.e., amino acids). If two nucleotides were used to code for one amino acid, then only 16 (or 42) different code words could be formed, which would be an insufficient number. However, if a group of three nucleotides is used for each code word, then 64 (or 43) code words can be formed. Any code using groups of three or more nucleotides will have more than enough units to encode 20 amino acids. Many such coding systems are mathematically possible. However, the actual genetic code used by cells is a triplet code, with every three nucleotides being “read” from a specified starting point in the mRNA. Each triplet is called a codon. Of the 64 possible codons in the genetic code, 61 specify individual amino acids and three are stop codons. Table 4-2 shows that most amino acids are encoded by more than one codon. Only two — methionine and tryptophan — have a single codon; at the other extreme, leucine, serine, and arginine are each specified by six different codons. The different codons for a given amino acid are said to be synonymous. The code itself is termed degenerate, which means that it contains redundancies. Table 4-2. The Genetic Code (RNA to Amino Acids)*. Table 4-2 The Genetic Code (RNA to Amino Acids)*. Synthesis of all protein chains in prokaryotic and eukaryotic cells begins with the amino acid methionine. In most mRNAs, the start (initiator) codon specifying this aminoterminal methionine is AUG. In a few bacterial mRNAs, GUG is used as the initiator codon, and CUG occasionally is used as an initiator codon for methionine in eukaryotes. The three codons UAA, UGA, and UAG do not specify amino acids but constitute stop (terminator) signals that mark the carboxyl terminus of protein chains in almost all cells. The sequence of codons that runs from a specific start site to a terminating codon is called a reading frame. This precise linear array of ribonucleotides in groups of three in mRNA specifies the precise linear sequence of amino acids in a protein and also signals where synthesis of the protein chain starts and stops. Because the genetic code is a commaless, overlapping triplet code, a particular mRNA theoretically could be translated in three different reading frames. Indeed some mRNAs have been shown to contain overlapping information that can be translated in different reading frames, yielding different polypeptides (Figure 4-21). The vast majority of mRNAs, however, can be read in only one frame because stop codons encountered in the other two possible reading frames terminate translation before a functional protein is produced. Another unusual coding arrangement occurs be- cause of frameshifting. In this case the protein-synthesizing machinery may read four nucleotides as one amino acid and then continue reading triplets, or it may back up one base and read all succeeding triplets in the new frame until termination of the chain occurs. These frameshifts are not common events, but a few dozen such instances are known. Figure 4-21. Example of how the genetic code — an overlapping, commaless triplet code — can be read in two different frames. Figure 4-21 Example of how the genetic code — an overlapping, commaless triplet code — can be read in two different frames. If translation of the mRNA sequence shown begins at two different upstream start sites (not (more...) The meaning of each codon is the same in most known organisms — a strong argument that life on earth evolved only once. Recently the genetic code has been found to differ for a few codons in many mitochondria, in ciliated protozoans, and in Acetabularia, a single-celled plant. As shown in Table 4-3, most of these changes involve reading of normal stop codons as amino acids, not an exchange of one amino acid for another. It is now thought that these exceptions to the general code are later evolutionary developments; that is, at no single time was the code immutably fixed, although massive changes were not tolerated once a general code began to function early in evolution. Table 4-3. Unusual Codon Usage in Nuclear and Mitochondrial Genes. Table 4-3 Unusual Codon Usage in Nuclear and Mitochondrial Genes.
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02 BMW 5 Speed Supercharged Ethanol Burnin Meth Injected E53 |
#160
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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior Dallas |
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