8.4 Specialized Membranes

Question 1

What is the resting membrane potential for most cells?

Answer 1

• between −40 and −80 mV, although the potential can rise as high as +35 mV during depolarization of the cell

Question 2

Nernst Equation

Answer 2

• can be used to determine the membrane potential from the intra- and extracellular concentrations of the various ions
• E = 61.5/z * log * [ion]outside/[ion]inside

Question 3

Na+/K+ ATPase

Answer 3

• One of the main functions of the Na+/K+ ATPase is to maintain a low concentration of sodium ions and high concentration of potassium ions intracellularly by pumping three sodium ions out for every two potassium ions pumped in
• This movement of ions removes one positive charge from the intracellular space of the cell, which maintains the negative resting potential of the cell

Question 4

Why’re mitochondria called the “powerhouse” of the cell?

Answer 4

• because of their ability to produce ATP by oxidative respiration

Question 5

Outer Mitochondrial Membrane

Answer 5

• completely surrounds the inner mitochondrial membrane, with the presence of a small intermembrane space in between the two layers.
• highly permeable due to many large pores that allow the passage of ions and small proteins

Question 6

Inner Mitochondrial Membrane

Answer 6

• contains numerous infoldings, known as cristae, which increase the available surface area for the integral proteins associated with the membrane
• has a much more restricted permeability compared to the outer mitochondrial membrane
• encloses the mitochondrial matrix, where the citric acid cycle produces high energy electron carriers used in the electron transport chain