NAU BIO 344 Posner Final Exam Questions with Correct Answers In a polarized cell, a barrier is created by a specific type of intercellular junction that maintains the separation of membrane proteins and between the apical and the basal sides of the cell. This barrier
is called a: - Correct Answer tight junction
What secondary structure found in proteins is often used to enable it to cross a membrane? - Correct Answer alpha helices An inhibitory acetylcholine receptor would - Correct Answer be a K+ channel The nonpolar part of a phospholipids consists of - Correct Answer fatty acid chains Which of the following is true concerning passive transport and active transport: - Correct Answer passive transport transfers molecules down an electrochemical gradient while active transport transfers molecules against an electrochemical gradient An example of an amphiphilic phosphoglyceride is: - Correct Answer phosphatidlyserine Reactions that add a phosphate to specific sites on proteins in an ATP dependent manner are important in cell signaling. The type of enzyme that catalyzes this reaction is: - Correct Answer a protein kinase In a depolarized membrane, repolarization of the neural membrane would occur as a result of: - Correct Answer opening of K+ channels How does an action potential travel down an axon? - Correct Answer voltage gated Na+ channels go from closed to open to inactivated in an orchestrated sequential manner In the presynaptic nerve cell, opening of voltage gated Ca+2 channels at the nerve terminal leads to:
- Correct Answer exocytosis of the contents of secretory vesicles into the synaptic cleft
The Na+-K+ pump requires ______ molecule(s) of ATP to transport ______ Na+ ions out of the cell and _______ K+ ions into the cell. - Correct Answer 1, 3, 2 1 / 2
Phospholipase C and Phospholipase A1 differs differ - Correct Answer in the specific site where they cleave phospholipids Which of the following are used to transport K+ ions against their electrochemical gradient? - Correct Answer the sodium potassium pump Why is it that in a resting neuron with K+ leak channels open, there are different concentrations of K+ ions on the two sides of the plasma membrane? - Correct Answer the membrane potential of a cell is negative and thus the equilibrium concentration of positively charged K+ ions is higher inside than outside the cell.Phosphatidylinositol 3-Kinase (also known as PI3K) is a lipid kinase. The 3 is letting you know that: - Correct Answer it catalyzes the addition of a phosphate to the 3 position of the inositol ring.A glycolipid that is part of the plasma membrane will be found: - Correct Answer only on the side of the bilayer that faces away from the cell (towards the extracellular fluid) When transporting a negatively charged ion through a ligand gated ion channel across the plasma membrane, which of the following is True? - Correct Answer the direction of transport is determined by both the concentration gradient and the membrane potential Both lipid and protein molecules can diffuse in the plane of a membrane. This is referred to as: - Correct Answer Lateral diffusion The forces that hold together the lipids in the membranes that surround organelles are: - Correct Answer Non-Covalent interactions A prokaryotic organism is isolated from a hydrothermal vent in Yellowstone national park where despite the fact that the temperature is extremely high, it has been thriving. In the plasma membrane of such an organism, which of the following concerning its phospholipid composition will help it adapt to the high temperature of its environment? - Correct Answer a predominance of long chain saturated fatty acids The reason that an action potentials cannot move backward is: - Correct Answer voltage gated sodium ion channels cannot go directly from the inactive state to open The sodium potassium pump is a - Correct Answer P-type ATPase
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