Answer to Question 1
All parts of a neuron are covered by a membrane about 8 nanometers (nm) thick (just less than 0.00001 mm), composed of two layers (free to float relative to each other) of phospholipid molecules (containing chains of fatty acids and a phosphate group). Embedded among the phospholipids are cylindrical protein molecules through which various chemicals can pass. The structure of the membrane and its proteins controls the flow of chemicals between the inside and outside of the cell. When at rest, the membrane maintains an electrical gradient, also known as polarizationa difference in electrical charge between the inside and outside of the cell. The neuron inside the membrane has a slightly negative electrical potential with respect to the outside, mainly because of negatively charged proteins inside the cell. This difference in voltage is called the resting potential.
Answer to Question 2
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Models of the α helix, showing different aspects of its structure
Neuronal action potential.
Kinetic versus Potential Energy
PV cells have potential for domestic and commercial use
Describe the functions of fat in the body
The Ames test, which screens compounds for potential mutagenicity