14which of the following is true regarding G proteins 15exoc

QUESTION 14 Which of the following is true regarding G proteins? They require GTP binding BThey are activated by G-protein coupled receptors C. They are extracellular signals D. A & B E. A, B, & C QUESTION 15 sis is the opposite of A osis o B. Lactosis. C. Halitosis D. Chemocytosis E. Stenosis QUESTION 16 concentration of solutes outside the cell compared to the inside. An isotonic solution has the same greater lower faster

Solution

1. Among the given options A and B are true regarding G-proteins

G-proteins are also known as guanine nucleotide-binding proteins. These are proteins that are involved in transmitting molecular signals from outside the cell to interior.

They bind and hydrolyse guanosine triphosphate (GTP) to guanosine diphosphate (GDP). When they are bound to GTP it means they are on and when they are bound to GDP they are off.

G-proteins are activated by G-coupled receptor which is a transmembrane receptor. G-Proteins exchange their GTP to GDP present on receptor and gets activated.

The question says that g-proteins are extracellular signals which is not true. These are proteins are present inside the cell and transmit extracellular signals.

2. Opposite of exocytosis is endocytosis

Exocytosis: it is a form of active transport in which molecules are expelled out using energy.

Endocytosis: is a form of active transport in which molecules are transported into the cell by using energy.

3. An isotonic solution has same concentration of solute in both outside and inside of the cell. There will be no exchange of matter through the cell in such situation. Cell is said to be in equilibrium.