Exam 1 – Lecture 2: Dr. Langston Flashcards
What is biotransport?
Movement of substance through the cell membrane
What does the cell membrane regulate?
The transfer of substances into and out of the cell
What are mechanisms of biotransport?
Passive diffusion
Facilitated diffusion
Active transport
Endocytosis (pinocytosis/phagocytosis)
What is the cell membrane structure?
Fluid mosaic model of the cell membrane
Phospholipid is the basic layer
What do proteins provide to a membrane?
Specificity
What are proteins defined by?
Mode of association with the lipid bilayer
What are some integral proteins?
Channels
Pores
Carriers
Enzymes
What are some peripheral proteins?
Enzymes
Intracellular signal mediators
What do integral proteins do?
Pass all the way through the membrane
What do peripheral proteins do?
They are embedded into one of the 2 sided, but do not go all the way through
What does the “glyco” prefix refer to?
Sugar/carbohydrate
What makes up the majority of integral proteins?
Glycoproteins
What are 2 types of glycoproteins?
Proteoglycans
Glycocalyx
What is a glycocalyx?
A glycoprotein covering that surrounds the cell membranes
What are GAGs (glycosaminoglycan) designed to do?
Supplement the glycoproteins, usually for joint health
What amount of cholesterol is present in the membranes?
Varying amounts
What does cholesterol do?
Decreases membrane fluidity and permeability
Increases membrane flexibility and stability
What is the head of the phospholipid like?
Polar and hydrophilic
What is the tail of the phospholipid like?
Nonpolar and hydrophobic
What is the rate of diffusion governed by?
Fick’s Law of Diffusion
In Fick’s Law of Diffusion, the characteristics of what 2 things are used to determine the rate of diffusion?
Membrane and solute
What are the characteristics of the membrane used for Fick’s Law of Diffusion?
Surface area
Membrane thickness
Diffusion
What are the characteristics of solute used for Fick’s Law of Diffusion?
Oil-water partition
Concentration difference for solute
For a solute to passively diffuse through a membrane, what must it be like?
Lipid soluble
Unionized
Small
What is the membrane a major route of cell entry for?
Many drugs
What can pass easily through the membrane?
Oxygen, CO2, nitrogen
If an ion has a charge, how will it cross the membrane?
Not very well. It must be relatively neutral to cross
Will bound proteins cross the membrane?
No, only unbound
How does water primarily enter the cell?
By pores that are channel proteins
What do facilitated diffusion gated protein channels play a role in?
Ion and neurotransmitter passage
Which is more negative, the inside or outside of the cell?
Inside
What are the 2 types of gated channels?
Voltage-gated
Ligand-gated
What is depolarization?
The electrical impulse coming down the nerve
What is a ligand?
Any substance that binds to a receptor to create a response
How does muscle contract?
Via ligand-gated channels
What is facilitated diffusion?
A type of passive diffusion that utilizes a carrier protein for the solute to cross the membrane
Does facilitated diffusion use energy?
No
What can facilitated diffusion become unlike passive diffusion?
Saturated
What does active transport do?
Uses a carrier protein to move solute against a concentration gradient
Requires energy
What are the 2 types of active transport?
Primary and secondary
What is primary active transport?
Uses a direct expenditure of ATP as the energy source
What is secondary active transport?
Uses the energy derived secondarily from energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane, created originally by primary active transport
What is a very important type of active transport?
Na/K transport
What does the Na/K ATPase pump do?
Maintains the sodium and potassium concentration differences across the cell membrane
Controls cell volume
Establishes a negative electrical voltage in the cell
How much of the cell’s energy requirement is devoted to pumping sodium out an potassium in the cell?
60-70%
What are 2 other primary active transport systems that are important?
Calcium ATPase pump
H+-K+ ATPase
What is the calcium ATPase involved in?
Muscle contraction
What are the 2 types of secondary active transport?
Co-transport (symport) Counter transport (antiport)
What are 2 types of symport systems?
Sodium-glucose co-transport
Sodium-amino acid co-transport
What are 2 types of antiport systems?
Sodium-calcium counter-transport
Sodium-hydrogen counter transport
What does symport mean?
Both molecules move the same way
What does antiport mean?
One ion moves one way and the other moves in the other direction
What is pinocytosis?
Cell drinking
Used to move very large molecules in a solution inside the cell
What is pinocytosis used with?
Very large, charged molecules that have properties that won’t typically let it diffuse
What is phagocytosis?
Cell eating
Used to move large particles instead of molecules
What is the rule of thumb for water and sodium?
Water follows sodium
What does active transport through cellular sheets often involve?
A combination of biotransport processes
How can you combat dehydration?
Sodium and a little bit of glucose cause water absorption
How can you replenish fluids?
Oral electrolyte solutions
