LS1a_L16_notes08-1

LS1a_L16_notes08-1 - LIFE SCIENCE 1a S PROF. ROBERT LUE...

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1a L I F E S C I E N C E S PROF. ROBERT LUE NOVEMBER 6, 2008 1
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PROF. ROBERT LUE NOVEMBER 6, 2008 1a L I F E S C I E N C E S 5’-TTA ATA TTC GAA AGC TGC ATC GAA AAC TGT GAA TCA-3’ 3’-AAT TAT AAG CTT TCG ACG TAG CTT TTG ACA CTT AGT-5’ 5’-UUA AUA UUC GAA AGC UGC AUC GAA AAC UGU GAA UCA-3’ 2
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1a L I F E S C I E N C E S 5’-TTA ATA TTC GAA AGC TGC ATC GAA AAC TGT GAA TCA-3’ 3’-AAT TAT AAG CTT TCG ACG TAG CTT TTG ACA CTT AGT-5’ 5’-UUA AUA UUC GAA AGC UGC AUC GAA AAC UGU GAA UCA-3’ Template Non-template = Coding = Non-coding = Sense = Anti-sense There are a variety of names used to designate the two strands of DNA that make up gene sequences. The nomenclature is related to either transcription (RNA synthesis) or to translation (protein synthesis). In the case of the former, the strand that serves as the template upon which the complementary RNA chain is polymerized is called the template strand, while the other strand is called the non-template strand. If we shift our point of reference to translation, then the non-template strand is described as the coding strand since it matches the sequence of the complementary RNA (with the substitution of uracil for thymidine), which is used to direct the assembly of the amino acid sequence in the protein. From this perspective, the template strand is therefore described as the non-coding strand. Finally, if we assume that a genetic sequence only makes sense in light of its ability to direct protein synthesis, then the coding strand could also be described as the sense strand. Consequently, from this point of view the non-coding strand could be described as the anti-sense strand. 3
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Translation: the RNA-directed synthesis of proteins 1. The role of RNA in protein synthesis - Three classes of RNA are required to synthesize proteins - mRNAs are decoded in sets of three nucleotides - The structure and function of transfer RNA - Proofreading by aminoacyl-tRNA synthetase 2. The translation machinery and cycle - The structure of the ribosome - The protein translation cycle - Starting and stopping translation - Elongation factors enhance the accuracy of translation 4
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Three classes of RNA are required to synthesize proteins Messenger RNA (mRNA) serves as the informational template Transfer RNA (tRNA) are molecular adaptors that match amino acids to the mRNA code Ribosomal RNA (rRNA) associate with proteins to form the ribosome The ribosome is a macromolecular machine consisting of proteins and RNA Decodes the mRNA and promotes the polymerization of amino acids into proteins Ribosome model with tRNA and rRNA Protein translation is the whole process by which the nucleotide sequence of an mRNA is used to order and to join the amino acids in a protein. DNA stores the information-rich code required for protein synthesis and RNA is the molecular intermediary that carries out the instructions encoded in DNA. On the other hand, most of the activities in the cell are carried out by proteins. As Dan pointed out earlier, proteins are the macromolecular workhorses of the cell and the
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LS1a_L16_notes08-1 - LIFE SCIENCE 1a S PROF. ROBERT LUE...

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