580.221 BME Molecules and Cells L06 Dogma of MolBiol 1 p 1Lecture Six – Dogma of MolBiol I -- DNA replication & DNA sequencing Outline: Central Dogma of Molecular Biology Nucleic Acids Replication Central Dogma of Molecular Biology Replication: Using a DNA template to make DNA. Key enzyme : DNA polymerase Transcription : Using a DNA template to make RNA. Key enzyme : RNA polymerase Translation: Using an RNA template to make PROTEIN. Key complex : ribosome (rRNA + proteins) Reverse transcription: Using an RNA template to make DNA (Doesn’t normally happen in the human body but some viruses do this. Key enzyme : Reverse transcriptase Information can flow back indirectly as proteins affect transcription and translation; proteins don’t normally code for RNA and RNA doesn’t normally make DNA (Some viruses can do this, creating disease.) Nucleic Acids The nucleic acids (RNA and DNA) are polymers. Their monomers are nucleotides. Nucleotide= phosphate group(s) (1-3) + sugar + base Nucleoside= sugar + base The sugar is ribose for RNA monomers, deoxyribose for DNA monomers. The deoxy group refers to the 2’ carbon of the sugar molecule, which is not involved in the condensation reactions to build the backbone of the nucleic acids. The condensation reactions give a phosphodiester bondbetween the 3’ and 5’ carbons of two sugars. We write a nucleotide as NTP, or Nucleoside TriPhosphate (dNTP for the deoxyribose form) or as NDP/dNDP (diphosphate) or NMP/dNMP (monophosphate). The basesused in DNA are divided into two groups : Purines(2 ring structure) – Guanine (G) and Adenine (A) Pyrimidines(1 ring structure) - Cytosine (C) and Thymine (T) In RNA, Thymine is replaced by Uracil (U)
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