Which of the following general statement(s) about a g protein–coupled receptor is (are) true? a. it contains 12 transmembrane domains. b. it is positioned with the n-terminus on the cytoplasmic face of the membrane. c. it is positioned with the c-terminus on the cytoplasmic face of the membrane. d. all of the above.

c. It is positioned with the C-terminus on the cytoplasmic face of the membrane.

Explanation:

G protein-coupled receptor or GPCR is a protein receptor. It is present only in eukaryotes. It is part of two main signal transduction pathways: phosphatidylinositol signal pathway and cAMP signal pathway. When a ligand binds to it, there is a confirmational change in it which leads to activation of G protein.

GPCR is an integral membrane protein receptor and has seven transmembrane (membrane spanning) domains. N terminus (NH2 part) of the receptor is extracellular and C terminus (COOH part) of the receptor is cytoplasmic. Hence option c is correct.  

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.