Online readings notes

Necessary Noise
• Looks at expression of ComK gene, which allows bacteria to take up DNA form the environment.
• Ex. In mouse experiment with glossy and rough bacteria. DNA from dead glossy and live rough bacteria had the ability to take that DNA from surrounding environment and incorporate into their characteristics. SO when mouse dies live glossy bacteria was cultured from mouse. ComK allows this to happen.
• Constitutively expressed gene=gene that’s always expressed. Doesn’t depend on environmental conditions.
• Phenotypic: Observable characteristics. What genes are expressed.
• Transcription factor: any protein that can bind to DNA to influence (generally activate) transcription of a gene
• Comk protein acts as a transcription factor and is its own transcription factor. It binds to DNA to make more ComK.
• Promoter region: where transcription factor binds on DNA to  transcription of DNARNA
• Actually all previous bullets are not always true according to article

Programmed ribosomal shifting goes beyond viruses
• Reading frame=codon being translated to amino acid sequence
• AUG=start codon which defines the reading frame
• Stop codon= translation stops at UGA because there is no complementary tRNA
• Release factor binds to the stop codon.
• Paper talks about release factor 2- protein that binds with UGA, detaches final tRNA from its amino acid. ( RF 1 binds with other 2 stop codons.)
• Paper talks about another means of gene expression by having ribosome intentionally frame shift.
• Example ribosome is moving down the line. At stop codon- ribosome then pauses because no anti codons or release factor 2 match, as a result ribosome shifts forward one base. This gives us a new reading frame.
• Release factor 2 will stop its own translation.
• Ribosomal frameshift is not a mutation just a change to the way the mRNA is translated to the protein.

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