NURSING EXAM QUESTIONS
MICROBIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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There is a decrease in levels of a catabolite(cAMP) promoting glucose utilization.
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There is an increase in the level of catabolite (cAMP) which promotes glucose utilization.
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lactose utilization is supressed when glucose is available
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glucose is a monosaccharide and is thus simpler, therefore it is utilized first than polysaccharides
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Detailed explanation-1: -Glucose and related sugars repress the transcription of genes encoding enzymes required for the utilization of alternative carbon sources; some of these genes are also repressed by other sugars such as galactose, and the process is known as catabolite repression.
Detailed explanation-2: -Extracellular glucose affects the lactose operon activation by inhibiting the production of cAMP (catabolite repression) and by reducing the efficiency of lactose permease to transport lactose molecules into the cell (inducer exclusion).
Detailed explanation-3: -If both glucose and lactose are both present, lactose binds to the repressor and prevents it from binding to the operator region. The block of lac gene transcription is thus lifted, and a small amount of mRNA is produced.
Detailed explanation-4: -After glucose is exhausted only then bacterial growth occurs on lactose. Since the abundance of glucose suppresses enzymes for utilising lactose, the repression is called catabolite or glucose effect.