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Chapter 15 Lecture and Reading Note taking Template Fill in this outline in lecture then use your textbook to add to it Notes from just the lecture are not enough to do well in this class 1 The Nature of Genes a The one gene one polypeptide hypothesis is a good starting point to understand gene expression Briefly describe it b Central Dogma of Biology Protein i Describes the one direction flow of information in cells as DNA to RNA to ii How does the discovery of reverse transcriptase alter the central dogma iii Draw the central dogma without reverse transcriptase as in Fig 15 2 c Definitions 1 DNA RNA Protein ii Transcription DNA RNA 1 DNA directed synthesis of RNA 2 Only one template strand of DNA used 3 U in DNA replaced by T in RNA 4 mRNA used to direct synthesis of polypeptides iii Translation RNA Protein 1 Synthesis of polypeptides 2 Takes place at ribosomes 3 Requires several kinds of RNA RNA genome into DNA v Reverse transcriptase iv Retrovirus they violate this order using reverse transcriptase to convert their d What roles do the following types of RNA have in gene expression i mRNA messanger transcription ii iii iv Gene expression creates proteins that are seen in phenotypes and also in rRNA ribosome tRNA transfer protein synthesis proteins that drive the cell cycle 2 The Genetic Code a What are codons and how are they related to amino acids i Block of 3 DNA nucleotides corresponding to an amino acid ii Code is universal creates the codes for amino acids iii Code is degenerate 64 possible codons 61 used to make amino acids 20 amino acids used for proteins 3 stop codons 1 start codon AUG b What is meant by the reading frame and why is this important c Define frameshift mutation i ii Indicates importance of reading frame If an amino acid is one frame off all the others behind it will be off causing something completely different d How many codons are there in the genetic code e What is the role of start and stop codons f What is meant by the code is degenerate but specific Chapter 15 Lecture and Reading Note taking Template g With the exception of mitochondrial chloroplast and some early protists the code is universal i Explain this statement ii Also explain how this concept is related to the evolution of organisms iii Explain the importance of this concept to genetic engineering 3 Prokaryotic Transcription Look at the Learning Outcomes listed at the start of section 15 3 With those in mind create your own outline of this section Use the bold headers as the general flow and include a brief summary 1 2 sentences and key words of what that header means I have done the first one for you as an example you will have a total of 5 headers It is important to be able to summarize information to the key points there is too much of it otherwise Each of the diagrams in this section are also important and helpful a Prokaryotes have a single RNA Polymerase b c Initiation of mRNA synthesis doesn t require a primer Initiation starts at promoter sequences on DNA i Forms a recognition and binding site for RNA polymerase ii Upstream of the start site iii Asymmetrical indicates site of initiation and direction of transcription d Requires i Promoter ii Start site iii Termination site 1 This enzyme exists in two subunits a The core polymerase synthesizes RNA from the DNA template b The holoenzyme initiates the synthesis the core polymerase cannot e Elongation f Termination i Grows in the 5 3 adding ribonucleotides ii Transcription bubble i Stop sequence ii RNA DNA hybrid within the transcription bubble dissociates iii RNA polymerase releases the DNA iv DNA rewinds v Hairpin structure is an example of a terminator g Prokaryotic transcription is coupled to translation h Operon i Grouping of functionally related genes ii Multiple enzymes for a pathway 4 Eukaryotic Transcription a How many RNA polymerases do eukaryotes use for gene expression How does this compare to prokaryotes b 3 different RNA polymerases that work together in nucleus Chapter 15 Lecture and Reading Note taking Template c i RNA polymerase i transcribes rRNA ii RNA polymerase ii transcribes mRNA iii RNA polymerase iii 1 Each have own promoter Initiation of transcription requires a series of transcription factors d e Termination f Does each RNA polymerase have its own promoter or do they share a promoter i Have their own g Initiation of transcription in eukaryotes differs from prokaryotes in that eukaryotes require 3 to help form an initiation complex with the RNA polymerase h List and describe the three ways eukaryotic transcripts are modified in eukaryotes the primary transcript must be modified to become mature mRNA i ii i Again each of these diagrams in this section are important and helpful 5 Eukaryotic pre mRNA Splicing a Many eukaryotic genes have sequences in the DNA that are not in the mRNA Fig 15 12 and 15 13 Define these terms i Introns non coding sequences INTervening sequences ii Exons sequences that will be translated or EXpressed iii Splicing iv Spliceosome removes introns v snRPs cluster with other proteins to form spliceosome to remove introns vi alternative splicing single primary transcript can be spliced into different mRNAs vii primary transcript viii mature mRNA over 100 000 proteins b The human genome has 25 000 genes How are those 25 000 genes able to express i Able to get different gens due to alternative splicing 6 The Structure of tRNA and Ribosomes a We are getting ready to learn about translation which occurs on the ribosome It also utilizes tRNA tRNAs interact with the mRNA and with amino acids b i the accepter end is charged with an amino acid ii The other end has an anticodon Define anticodon iii tRNA molecules carry amino acids to the ribosome for incorporation into a polypeptide 1 anticodon iv tRNA charging reaction ribosomes do not verify amino acid attached to tRNA c Ribosomes Fi 15 16 i Are made of two subunits simply named Chapter 15 Lecture and Reading Note taking Template ii Have multiple tRNA binding sites Explain the three binding sites 1 P site binds to the growing peptide chain 2 A site binds to the next amino acid 3 E site last amino acid exit or empty site iii The ribosome has 2 primary functions 1 Decode the mRNA 2 Form peptide bonds through an enzymatic component of the ribosome 7 The Process of Translation a Use the summary at the end of the chapter and the animations to understand translation This is all the detail that you need to know In prokaryotes initiation complex includes


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SDSU BIOL 151 - Chapter 15

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