Multiple Choice
Is there a difference between oncogenes and tumor suppressor genes?
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12. Biosignaling
Signaling Defects & Cancer
Multiple Choice
In the context of signaling defects and cancer, which nucleotide-bound state represents the active form of the Ras protein that can propagate downstream signaling?
A
Ras covalently phosphorylated on serine
B
Ras with no nucleotide bound (apo-Ras)
C
Ras bound to GDP
D
Ras bound to GTP
Verified step by step guidance1
Understand that Ras is a small GTPase protein involved in cell signaling pathways that regulate cell growth and differentiation.
Recognize that Ras cycles between an active and inactive state depending on the nucleotide it is bound to: GDP or GTP.
Recall that when Ras is bound to GDP, it is in its inactive form and cannot propagate downstream signaling.
Know that when Ras is bound to GTP, it undergoes a conformational change that allows it to interact with downstream effectors, thus representing the active form.
Note that modifications like covalent phosphorylation on serine or the absence of nucleotide (apo-Ras) do not represent the active signaling state of Ras.
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