MCDB 2150 1st Edition Lecture 19Outline of Last Lecture - RNA interference (RNAi)o miRNA & siRNA- Chromatin structureo Histone modificationo MethylationOutline of Current Lecture - Gene expression- Chromatin structure- Post-transcriptional control- Post-translational modificationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Gene expressionChromatin Structure:1.) Histonesa. Addition of methyl groups to histone protein tails = acetylation = acetylase enzyme – causes coiling up2.) Methylated DNA (on cytosine basesnext to guanine CpG) prevents transcription factors from binding toDNAOften, site-specific methylation occurs on the thepromoter regions = preventing transcription3.) Regulatory regionsa. Part of DNA with activator-bindingsites b. sometimes found:i. before the promoterii. in enhancer regionsiii. in repressor regionsPost-transcriptional control: degradation of RNA- Increased degradationo 5’-cap removalo shortening of the poly (A) tail- Decreased degradationo Binding of other factors to 3’ UTRPost-Translational modification: protein in further modified- Phosphorylation (often activates protein)- Glycosylation (addition of sugar)- Folded into particular shape- Cleaved into smaller, active versions- Degradation: usually due to mis-foldingo Ubiquitination – addition of a particular
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