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:

Quantity Supplied

Quantity Supplied refers to the amount of goods or services that sellers are willing and able to sell at a given price over a specified period of time.

Price Increase

When the cost of goods or services rises over a period.

Long Run

A period in economics where all factors of production can be adjusted, allowing firms to change their output levels based on market demands.

Marginal Revenue Curve

A graphical representation showing how marginal revenue varies with changes in quantity sold, highlighting the additional revenue from selling one more unit.