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SCS 2159 Lecture 2 Flash Cards Study Guide
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SCS 2159 Lecture 2 Flash Cards StudyGuide
What does permeable mean? - Answer Fluid or particles can pass through
What type of molecules readily pass directly through the cell membrane? - Answer
-small, neutral and non-polar molecules
i.e. CO2, O2, fats,
What type of molecules do NOT readily pass directly through the cell membrane? -
Answer ions and polar molecules
i.e. Glucose, proteins, Na+
Type general types of Transport and compare them? - Answer Passive Transport is
spontaneous and does not require energy, goes down concentration gradient
Active Transport is not spontaneous and requires energy, goes up concentration
gradient
Define Concentration Gradient and what is the equation? - Answer -difference in particle
concentration from ECF and ICF
Delta C = Co - Ci
- negative delta C, means there is more solute inside the cell and thus will flow outwards
- positive delta C, means there is more solute outside the cell and will flow inwards
What is Flux? - Answer -the net number of molecules that cross the membrane in a given
length of time
True of False: the chemical driving force that is acting on a given substance depends
only on the concentration of that particular substance - Answer TRUE
What is membrane potential Vm? - Answer -a voltage or electrical charge across the
plasma membrane caused by unequal distribution of cations and anions
-this charge difference is a source of energy
-usually is is referred to the inside relative to the outside (i.e. Vm is -ve means the inside
of the cell is -ve and outside of cell is +ve
What are the two driving forces for transport? - Answer Electrical and Chemical
The direction fo the electrical driving force is determined by what? - Answer i) charge of
particle
, ii) charge/polarity of the ICF
If the membrane potential is negative, what type of ion dominates the ICF? - Answer
anions (negative ions)
Magnitude of electrical driving force depends on what? - Answer i) strength of
membrane potential
ii) amount of charge on a particle (1+, 2+, etc)
What is the electrochemical driving force? - Answer -sum of chemical and electrical
forces
-essentially it is the net force
True or False: When equilibrium potential (Ek) and membrane potential (Vm) are equal,
the net force is zero - Answer TRUE
Types of passive transport? - Answer i) simple diffusion
ii) facilitated diffusion
iii) diffusion through channels / ions channels
What is simple diffusion? - Answer -movement of a solute from an area of high
concentration to an area of low concentration
-passes membrane without any assistance
i.e. small lipid soluble molecules and gas
Factors which effect rate of simple diffusion? - Answer -magnitude of driving force /
concentration gradient
-membrane permeability
-membrane surface area
With respect to simple diffusion, what factors effect membrane permeability? - Answer
-lipophilicity of solute
-size and shape of solute
-temperature (not relevant for humans)
-membrane thickness
What is facilitated diffusion? - Answer -a type of passive transport which occurs through
a transmembrane carrier protein
-has specific binding sites for solutes
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