Lecture 3 & 4: Cell Membrane Flashcards
What are the 4 functions of cell membranes
1) Physical barrier (Separates ICF from ECF)
2) Gateway for exchange
3) Communication
4) Cell structure
Define the structure of cell membranes
a fluid mosaic model has phospholipid bilayers, proteins embedded on it and presence of sterols.
mostly made up of proteins and lipids
What are the four component molecules of cell membranes
1) Phospholipids
2) cholesterol
3) Sphingolipids
4) Proteins
What does cholesterol do in the cell membrane component molecules
slips between the fatty acid tails and maintains fluidity and slows down diffusion
Sphingolipids typically form what
a lipid raft
Define the two types of proteins
a) Integral = embedded proteins, three types, monotopic, biotypic and polytypic
b) Peripheral = attached to one of the sides by non covalent bonds
Define Diffusion
The movement of molecules from a region of high concentration to low concentration, down the concentration gradient
Diffusion is faster when
1) High temp
2) Short distances
3) Small molecules
Diffusion is slow when `
crossing the plasma membrane
What are the 5 things diffusion across a membrane depends on
1) Type of molecule
2) Concentration Gradient (^)
3) Surface area (^)
4) Temperature (^)
5) Composition of membrane (presence of cholesterol = (down)
Does division require atp?
No
When does Diffusion stop
until equilibrium is reached
What kind of time relationship does diffusion have
Distance squared
What two types of solutes can go through a cell membrane easily
hydrophobic, non polar
Small uncharged polar molecules
What is Ficks Law
A law of diffusion
Rate of division = Surface area X Concentration gradient X Membrane permeability
What is the formula for membrane permeability
Membrane permeability = Lipid solubility /
Molecule size
Define osmosis
The diffusion of water
Movement of water can cause what kind of pressure
osmotic pressure
What is the Normal Physiological concentrations of salts in the Extracellular membrane
K+ = 5mM Na+ = 145mM Cl- = 108 mM Ca2+ = 1mM
What is the normal physiological concentrations of salts in the Intracellular Membrane
K+ = 150mM
Na+ 15mM
Cl- = 5mM
Ca2+ = 0.0001 mM
Define isosmotic
Same
Define hyperosmotic
More osmolarity
Define Hyposomotic
Less osmolarity
Osmolarity can cause cells to ____ or ____
Shrink or Swell
In Hypertonic solution cells ______
Shrink
In Hypotonic solutions cells ____
Swell
Define tonicity
Is a comparative term , describes whether a cell changes volume (has no units)
What does Tonicity specifically tell us
If a cell swells or shrinks
Tonicity depends on both ____ and _____ solutes
penetrating and nonpenetrating solutes
Define protein-mediated transport
The movement of solutes across a membrane by proteins
The ICF has ?/3 of total body comp
2/3
The ECF has ?/3 of total body comp
1/3
What is a channel protein
a water filled pore with a hole in the middle, open to both the ECF and ICF
What are the two types of Channel proteins
Gated channels ( one side is closed until binding) Open channels, always open (typically leakage channels
True or False; Carrier proteins always form an open channel between the two sides of the membrane
False, Never
Define the process of carrier proteins
1) Passage open to one side
2) Molecule goes in
3) Transition state with both gates closed
4) Passage opens to other side
5) Gate to original side is closed
6) Molecule fucks off
what are the three types of carrier proteins
1) Uniport carriers - move 1 thing at a time
2) Symport carriers - moving two things in same direction at one time
3) Antiport carriers - moving 2 things in different directions at one time
What are the three energy requirement needed for carrier proteins
1) Faciliated diffusion
2) Primary active transport
3) Secondary active transport
Define facilitated diffusion
What is another name of it
As moving a molecule across the membrane via a carrier protein
Passive transport
Does facilitated diffusion require ATP?
No
Is Facilitated diffusion up or down the concentration gradient?
down
Does Primary active transport use ATP and what does it do regarding gradients?
Yes establishes
What is primary active transport commonly called
pumps
What is the most widely known example of primary active transport
Na+/K+/ATPase
At rest, the human body produces about how many watts of energy
100 watts
The Na+/K+/ATPase in the CNS accounts for how many watts of produced energy at rest
20 watts
Secondary active transport is known as, does it use ATP?
Active transport, does not directly utilize atp as a source of energy
Secondary active transports use what to move a molecule
Uses the concentration gradient of one molecule to move another against its gradient
What is a good example of a secondary active transporter
SGLT or Na+ glucose secondary
Epithelial transport utilizes what forms of transport
facilitated diffusion
primary and secondary active transport
What are the three types of vesicular transport
Phagocytoses
Endocytosis
Exocytosis
Define Phagocytoses
Cell engulfing a bacterium or other particles into a large membrane bound vesicle called PHAGOSOME
Define Endocytosis
Large molecules move into the cells
Define Exocytosis
Intracellular vesicles move to the cell membrane, fuse with it and then release contents into the ECF
