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Very similar to eukaryotes 1 termination of

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-Very similar to eukaryotes1.Termination of transcription is more complex in eukaryotesWhat is a major diference between this process in eukaryotic vs prokaryoticcells?-mRNA in eukaryotic cells (in the nucleus) goes throughRNAprocessing1.this is a process by which there is an addition of a cap and tail tothe ends of the pre-mRNA2.and then parts of the pre-mRNA (introns) are cut out of thesequence3.the cap and tail are there to help protect the mRNA fromdegradation4.the introns are specifc parts of the mRNA that will not beexpressed, in contrast to the parts that will be expressed (exons)othe exons are then glues together into a shorter piece ofmRNALecture 11: Genetic MutationsMutation-change in the DNA-once the change has occurred the mutant DNA is treated like any otherstrand of DNA-all current DNA was “mutant” DNA at some time in the pastSeveral types of Mutation-substitution: one base is substituted for another1.in some cases, the substitution doesn’t afect thenucleotide, therefore doesn’t afect the structure ofthe protein and has no efect on the phenotype ofthe organism50Downloaded by SYED Hassan Ali ([email protected])lOMoARcPSD|4552461
2.we have cases where more than one codon codes for the sameamino acid3.can also have the case where a diferent nucleotide will result ina new amino acidothe consequences of this mistake depends on many factorshow diferent is the new amino acid?Where is it in the chain?4.Also possible to have a mutation that results in stop codon whereit shouldn’t beoVery major mistake-Insertion: one or more nucleotides are inserted into the DNA-Deletion: one or more nucleotides deleted from the DNA1.Inserting/deleting nucleotides causes a shift that will afect everysubsequent amino acid (since the nucleotides are read in pairs of3 – codon)2.Possible to have insertion/deletion of a whole tripletWhy do mutations happen?-Presence of mutagens1.Something that causes mutationoE.g. high energy radiation (gamma rays)oCertain chemicals (cigarette smoke)-DNA replication1.Not a perfect process, mistakes can occur2.About 1 error per 1-10 billion basesMutation rates vary based on-Presence/absence of mutagens-Environmental efects on DNA1.When cells are put under stress their replication fdelity tends tobreak down-Diferent parts of the DNA have higher mutation rates than others-Overall mutation rate in humans1.0.00000002 per base per zygote2.1 in 50 million bases per generation3.Average human has about 128 mutations (therefore mutationsare quite common)oMost of mutations will have little or no efectGene Regulation-The expression of genes is regulated-Genes are expressed only under certain conditions-Some genes only expressed at certain times-Come are expressed more than others-Some only expressed in certain cells-Control of transcriptionis the most important mechanism in thecontrol of gene transcription1.Negative control51Downloaded by SYED Hassan Ali ([email protected])lOMoARcPSD|4552461

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Term
Spring
Professor
N/A
Tags
Bacteria, Photosynthesis, Adenosine triphosphate, Syed Hassan Ali

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