LS1a_L14_notes08

LS1a_L14_notes08 - LIFE 5-UUA AUA UUC GAA 5-TTA ATA TTC GAA...

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PROF. ROBERT LUE OCTOBER 30, 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’ 1
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Nucleic acids in action: transcription and the programming of the cell 1. RNA structure and function - Structural components of RNA - Relative stability in comparison to DNA 2. From DNA to RNA: the process of transcription - Overview of intracellular information transfer - RNA polymerase transcribes RNA from a DNA template - Bacterial transcription as a model - The starting and stopping of transcription in bacteria - Eukaryotic transcription requires multiple initiation factors - Eukaryotic DNA is packaged with proteins - Eukaryotic RNA transcripts are chemically modified 3. Transcription is regulated in several different ways - Packaging of eukaryotic DNA facilitates gene regulation - Combinatorial control of gene transcription determines different cell types 2
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RNA: The other important nucleic acid The differing structures and chemical properties of DNA and RNA allow for different functions in the cell DNA has primarily one structure and one function RNA can adopt many structures and has many functions Ribonucleic acid, or RNA, has a similar basic molecular structure compared to DNA. Both RNA and DNA are nucleic acids and are made up of nucleotides. There are two important differences in their chemical structures which make them more suitable in their biological roles. DNA is perhaps boring and unimaginative compared to RNA. DNA has one important structure physiologically, the DNA double helix, but as we have seen this structure is perfect for its role in information storage. RNA has many more functions. It can transmit information in the cell, it can have enzymatic functions, it can help form the basic structure of macromolecular complexes, and for some viruses including HIV it comprises the viral genome. Andrew Fire and Craig Mello, won the Nobel Prize for discovering that double stranded RNAs can be used to reduce or abolish gene expression. This revealed a new mechanism for gene regulation and is called RNA interference (RNAi). 3
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RNA, like DNA, is formed from nucleotides Monomer Base Sugar Phosphate O O N N N NH 2 O N P O O O OH 1’ 2’ 3’ 4’ 5’ Polymer O HO OH HO 1' 2' 3' 4' 5' (D)- 2' D eoxyribose found in DNA O HO OH HO OH 1' 2' 3' 4' 5' (D)- R ibose found in RNA Ribose is the sugar of RNA Ribonucleic acid just like DNA is a polymer made up from nucleotides. However the nucleotides of RNA differ from those of DNA in two important ways. First, RNA uses a different sugar than DNA. This sugar, ribose, occupies the same position in the nucleotide as the sugar in DNA and its carbons are numbered similarly 1 ʼ -5 ʼ . The 5 ʼ carbon of ribose is linked to a phosphate group and the 3 ʼ carbon of ribose has a 3 ʼ -OH group. So the nucleotides of RNA can be linked into a chain in the same way as DNA with a sugar phosphate backbone.
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LS1a_L14_notes08 - LIFE 5-UUA AUA UUC GAA 5-TTA ATA TTC GAA...

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