Test on Hormone Receptor Pathways and Signaling

Question 1: Steroid hormones are lipid soluble, allowing them to pass directly through the cell membrane to bind with intracellular receptors.

A. Ano

B. Ne

Explanation: Steroid hormones are lipid soluble because they are derived from cholesterol. This lipid solubility enables them to pass right through the lipid bilayer of the cell membrane and bind onto receptors located inside the cell.

Question 2: Based on the study materials, which characteristic of peptide hormones prevents them from directly passing through the cell membrane?

A. They are too small to interact with the lipid bilayer.

B. They are water soluble and cannot dissolve in the lipid bilayer.

C. They are lipid soluble and repelled by the water inside the cell.

D. They possess an electric charge that neutralizes the membrane's permeability.

Explanation: The study materials state that peptide hormones are water soluble and, because the cell membrane is a phospholipid bilayer, these water-soluble hormones cannot penetrate through it as they are not soluble within the lipids. The text also mentions they are 'pretty big' and 'can have charges,' but the primary reason given for not passing through the lipid bilayer is their water solubility.

Question 3: When IP3 binds to its receptor on the smooth endoplasmic reticulum, a channel opens allowing sodium to flood into the cytoplasm.

A. Ano

B. Ne

Explanation: When IP3 binds to its specific receptor on the smooth endoplasmic reticulum, it opens a channel that causes calcium to start flooding out into the cytoplasm, not sodium.

Question 4: Calcium directly phosphorylates proteins after binding to calmodulin.

A. Ano

B. Ne

Explanation: Calcium binds to calmodulin, which then activates specific types of kinases. These kinases are responsible for phosphorylating various different types of proteins, not calcium directly.

Question 5: What happens immediately after IP3 binds to its specific receptor on the smooth endoplasmic reticulum or sarcoplasmic reticulum?

A. A specific channel opens, allowing calcium to flood out into the cytoplasm.

B. The receptor changes shape and activates the GQ protein.

C. Protein Kinase C is activated, leading to phosphorylation.

D. GDP binds to the G protein, turning it off.

Explanation: According to the study materials, when IP3 binds to its receptor on the smooth endoplasmic reticulum or sarcoplasmic reticulum, it opens up a specific channel, causing calcium to start getting pushed out into the cytoplasm.