Lecture Handout 5 - BIOT 101 Lecture Handout 5 Central...

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BIOT 101 Lecture Handout 5 Central Dogma of Biology Vocabulary 5’ cap DNA helicase DNA ligase DNA polymerase I DNA primase exons gene genetic code introns lagging strand leading strand Okazaki fragments origin of replication (ORI) peptide bond poly-A tail polymerase III post-transcriptional modification primer replication fork ribonucleic acid (RNA) RNA polymerase semiconservative replication single-strand binding proteins (SSB’s) splicing supercoils template topoisomerases transcription translation Objectives Be able to describe the process of DNA replication. Understand the role played by DNA polymerases I and III, the role of primase, helicase, topoisomerases and single-strand binding proteins. Understand the central dogma of biology. Understand the roles of transcription and translation in this central dogma. Understand the process of transcription and why this process occurs. Be able to describe the steps and enzymes involved in this process. Understand the processes of post-transcriptional modification that occur in the eukaryotic cell. Understand the process of translation and why this process occurs. Be able to describe the steps, enzymes and other materials involved in this process. Understand the idea of the codon. Know what is meant by the term genetic code. Given a DNA sequence, be able to determine the RNA sequence that would be transcribed. Given the genetic code, be able to translate a sequence of RNA into a sequence of amino acids. 1
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BIOT 101 Lecture Handout 5 Central Dogma of Biology I. Before any cell (either eukaryotic or prokaryotic) can divide, the genetic information stored in DNA must be copied with very few mistakes. This requires a mechanism that will produce two identical double helices from one initial double helix. The process by which the DNA sequence is faithfully duplicated is known as semiconservative replication . A. Replication begins with the unwinding of the DNA helix at a specific site known as the origin of replication ( ORI ). Unwinding is the result of the action of an enzyme known as DNA helicase . The freshly unwound DNA molecules would immediately snap back to being double stranded if not for the binding of proteins to the single-stranded DNA. These proteins are referred to as single-strand binding proteins (SSB’s). Their binding prevents the DNA from snapping back into its double helical structure. The action of the helicase creates “knots” in the yet to be unwound strand of DNA. These knots are referred to as supercoils . To relieve the supercoiling, an enzymes known as topoisomerases cut the supercoiled region, allow the DNA to unwind and rejoin the DNA molecule. The area where the DNA is being unwound and replicated is referred to as the replication fork .
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Lecture Handout 5 - BIOT 101 Lecture Handout 5 Central...

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