An investigator studying epigenetic mechanisms isolates histone proteins, the structural motifs involved in DNA binding and regulation of transcription. The peptide bonds of histone proteins are hydrolyzed and one type of amino acid is isolated. At normal body pH, this amino acid has a net charge of +1 . The investigator performs titration of this amino acid and obtains the graph shown. The isolated amino acid is most likely which of the following?
AProline
BLysine
CAspartate
DSerine
EHistidine
E. coli has the ability to regulate its enzymes to break down various sources of energy when available. It prevents waste by the use of the lac operon, which encodes a polycistronic transcript. At a low concentration of glucose and absence of lactose, which of the following occurs?
ADecreased cAMP levels result in poor binding to the catabolite activator protein
BIncreased cAMP levels result in binding to the catabolite activator protein
CIncreased allolactose levels bind to the repressor
DRepressor releases from lac operator
ETranscription of the lac Z, Y, and A genes increase
A 62-year-old woman presents to her primary care physician because of fever, fatigue, and shortness of breath. She has noticed that she has a number of bruises, but she attributes this to a hike she went on 1 week ago. She has diabetes and hypertension well controlled on medication and previously had an abdominal surgery but doesn’t remember why. On physical exam, she has some lumps in her neck and a palpable liver edge. Peripheral blood smear shows white blood cells with peroxidase positive eosinophilic cytoplasmic inclusions. The abnormal protein most likely seen in this disease normally has which of the following functions?
ABinding to anti-apoptotic factors
BBinding as cofactor to kinases
CInhibiting pro-apoptotic factors
DRecruiting histone acetylase proteins
EInteracting with IL-3 receptor
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