Release factors will bind in order to dissociate all machinery in place There

Release factors will bind in order to dissociate all

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Release factors will bind in order to dissociate all machinery in place There is no tRNA for the stop codon Be familiar with the process of mutation and how cells work to prevent it Substitutions: when one nucleotide is replace by another Insertion: the insertion of an extra nucleotide Deletion: the removal of a nucleotide that should otherwise be present Mis-sense changes the amino acid in the polypeptide sequence o May or may not change the actual protein o Can either be destructive, beneficial, or neutral Nonsense is a loss of function mutation
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o Nucleotide that changes in the codon cause the codon to become a chain-terminating codon o Makes the codon a premature stop codon Silent: change in nucleotide sequence but no change in amino acid Suppressor: two mutations that occur simultaneously, the second changes effect the first Causes of mutations o Strand slippage: one nucleotide bulges out of one strand, causing an extra nucleotide on the coding strand to be incorporated, while the other complementary parent strand codes a deletion o Depurination: purine is randomly left out, adenosine will take its place o Deamination: a C gets concerted to a U/T o Chemical agents: oxidizers can create free radicals, radiation can create free radicals and DNA strand breaks o Low UV energy: can create dimers between two thymines o Intercalators: copy the behavior of DNA bases and insert themselves in place o Induced: brought about by some agent, DNA repair o Nucleotide-excision repair: a kink is formed by a mismatch which is recognized and cut out, DNA pol III will fill in the gap o Direct Repair: an enzyme that is designed to do a specific fix, enzymatic o Base-excision repair: removes nitrogenous base from nucleotide o Mismatch repair: mismatched nucleotides occasionally get incorporated- causing kinks in DNA Mismatch repair enzymes recognize these kinks and replace the mismatched nucleotide Transition mutation: base substitutions in which one purine (A or G) is changed to another purine or pyrimidine to another pyrimidine Transversion: base substitution in which one purine is changed to a pyrimidine Forward: causes a change to the phenotype. Reverse: reverses the change in phenotype back to the wild type Part 2 – Chromosomes, bacteria and viruses Be familiar with the structure of eukaryotic chromosomes and compare with that of prokaryotes Prokaryotes: o One circular chromosome where DNA stored in nucleoid o Chromosomes split and divide during cell division through binary fission o Most are haploid
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Eukaryotes: o Multiple linear chromosomes, DNA in nucleus o Chromosome split and divide during cell division o Most eukaryotes are diploid Understand the inheritance of organeller genomes Mitochondria and Chloroplast have their own circular DNA These organelles are inherited by the mother Horizontal transfer of nucleus DNA to organelles Understand the types of chromosomal mutation (deletion, duplication, inversion, transversion) including non-disjunction and aneuploidy in somatic and gametic cells Above Understand polyploidy
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