BRS CELL PHYSIOLOGY EXAM QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
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BRS PHYSIOLOGY
BRS CELL PHYSIOLOGY EXAM QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
What are cell membranes primarily composed of?
Phospholipids and proteins.
What is the structure of phospholipids in the lipid bilayer?
Glycerol backbone as the hydrophilic head and two fatty acid tails as hydropho...
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BRS CELL PHYSIOLOGY EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS VERIFIED
What are cell membranes primarily composed of?
Phospholipids and proteins.
What is the structure of phospholipids in the lipid bilayer?
Glycerol backbone as the hydrophilic head and two fatty acid tails as hydrophobic tails.
How do lipid-soluble substances cross cell membranes?
They can dissolve in the hydrophobic lipid bilayer.
How do water-soluble substances cross cell membranes?
They may cross through water-filled channels, pores, or be transported by carriers.
What are integral proteins anchored to in the cell membrane?
Anchored to and embedded in the cell membrane through hydrophobic interactions.
What are examples of integral proteins?
Ion channels, transport proteins, receptors, and G proteins.
How are peripheral proteins attached to the cell membrane?
Loosely attached by electrostatic interactions and not covalently bound to membrane
components.
What are tight junctions also known as?
Tight junctions are also known as zonula occludens.
What type of cells are often connected by tight junctions?
Epithelial cells.
,What determines whether tight junctions may be an intercellular pathway for
solutes?
The size, charge, and characteristics of the tight junction.
How are gap junctions different from tight junctions?
Gap junctions permit intercellular communication.
Give an example of the function of gap junctions.
They permit current flow and electrical coupling between myocardial cells.
What is the only form of transport that is not carrier mediated?
Simple diffusion.
What is diffusion?
The movement of particles down an electrochemical gradient ('downhill').
What is the equation to measure diffusion?
J = − PA(C1 − C2)
How is the direction of flux indicated in the diffusion equation?
The minus sign indicates that the direction of flux is from high to low concentration.
What is permeability?
The ease with which a solute diffuses through a membrane.
What factors increase permeability?
An increase in the oil/water partition coefficient of the solute increases solubility in the
lipid of the membrane.
How does the radius (size) of the solute affect the diffusion coefficient and speed
of diffusion?
Increases the diffusion coefficient and speed of diffusion.
, What effect does membrane thickness have on diffusion distance?
Decreases the diffusion distance.
Which type of solutes have the highest permeabilities in lipid membranes?
Small hydrophobic solutes (e.g., O2, CO2).
How do hydrophilic solutes (e.g., Na+, K+) cross cell membranes?
Through water-filled channels, pores, or via transporters.
What does the flux of an ion depend on when crossing the membrane?
Both the concentration difference and the potential difference across the membrane.
What is stereospecificity in carrier-mediated transport?
It distinguishes between isomers, e.g., D-glucose is transported but L-isomer is not.
What happens to the transport rate as the concentration of the solute increases in
carrier-mediated transport?
It increases until the carriers are saturated.
What is the transport maximum (Tm) analogous to in carrier-mediated transport?
The maximum velocity (Vmax) in enzyme kinetics.
What is the competition in carrier-mediated transport?
Structurally related solutes compete for transport sites on carrier molecules.
What are the characteristics of facilitated diffusion?
Occurs down an electrochemical gradient, does not require metabolic energy, is carrier
mediated, and exhibits stereospecificity, saturation, and competition.
What is the role of insulin in glucose uptake by muscle and adipose cells?
Insulin is required for the carriers for facilitated diffusion of glucose.
What are the characteristics of primary active transport?
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