True/False about Expression of Bacteria and Eukaryotes. (Just want a look over t

Question

True/False about Expression of Bacteria and Eukaryotes. (Just want a look over them, I think I have the answers)

_____In the lac operon of E. coli, a constitutive mutant is one in which the three enzymes are produced regardless of the presence or absensence of lactose (I think True)

_____ Under a system of negative control, genetic expression occurs unless shut off by some form of regulator (I think True)

_____ Alternative RNA processing can result in different mRNAs that start with different exons ( I think True)

_____ A cell does not continually produce all the enzymes for which it possesses the gene potential( I think false)

_____ In eukaryotic cells, many active genes to be associated with highly compacted chromatin(unkown)

Explanation / Answer

What you thought are mostly true a) True b) True c) True d) True! This is because enzyme production (transcription and translation of enzyme genes) can be enhanced or diminished by a cell in response to changes in the cell's environment. Thus it need not continually produce enzymes for which it has gene potential. e) False. This is because DNA coding genes that are actively transcribed ("turned on") are more loosely packaged and are found associated with RNA polymerases (referred to as euchromatin) while DNA coding inactive genes ("turned off") are found associated with structural proteins and are more compactly packaged.

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