A Number of Mutations Have Been Described in G Proteins

question 99

Multiple Choice

A number of mutations have been described in G proteins, such as Ras, that have profound effects on their activity. For example, some mutations greatly increase the affinity of the G protein for GDP, making it very difficult for GDP to be exchanged for GTP. Other mutations prevent the hydrolysis of GTP to GDP. Which of the following scenarios would still result in a proliferation signal via the kinase cascade in the absence of ligand binding to its receptor kinase?

• A)a continuously active receptor and an inactive Map kinase pathway
• B)a Ras molecule that has no GTPase activity
• C)a continuously inactive MAP kinase pathway and an inactive Ras protein
• D)a continuously active Ras protein and an inactive MAP kinase pathway
• E)a continuously activated receptor in the absence of ligand

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Definitions:

Physiological Ailments

Physical diseases or disorders that affect the body's structures or organs.

Factitious Disorder

A mental disorder in which a person acts as if they have a physical or mental illness when they are not really sick, often done to assume the sick role and gain medical attention.

Munchausen Syndrome

is a psychiatric disorder where an individual deliberately produces or fabricates symptoms of illness in themselves for attention or sympathy.

Somatic Symptom Disorder

A psychological disorder characterized by an excessive focus on physical symptoms that cause significant distress or impairment.