Ch. 5 Membranes Flashcards
Where are phospholipids located?
In the bilayer of the membrane
What’s a fluid mosaic model?
a mosaic of proteins that float in/on the fluid lipid bilayer (like boats on a pond); created in 1972 by S. Johnathan Singer and Garth J. Nicholson
What’re the 4 components of a cellular membrane?
1) Phospholipid bilayer
2) Transmembrane proteins
3) interior protein network
4) Cell-surface markers
What is lipidomics?
the # and biological function of lipids
What are the three classes of lipids?
1) glycerol phospholipids
2) Sterols
3) Sphingolipids
Does an Ampipathic structure have hydrophobic, hydrophilic, or both regions?
Both
What’re the 7 functions of membrane proteins?
1) Transport
2) enzymes
3) cell surface receptors
4) cell surface markers
5) cell to cell adhesion
6) attachment to cytoskeleton
7) proteins that affect the membrane structure
What do anchoring molecules do?
Attach membrane proteins to the membrane surface
What’s passive transport?
the net movement of molecules through the membrane; no energy required
What’s diffusion?
net movement of molecules from high concentration to low concentration
What’s the major barrier for molecules that try to cross the biological membrane?
The interior is hydrophobic
What does facilitated diffusion do?
Assists molecules that can’t cross membranes easily by helping them move through proteins
Are channel proteins hydrophilic or hydrophobic?
Hydrophilic
What does an ion channel do?
Allow passage of ions through the non polar interior of the plasma membrane
What makes gated channels open and close?
Stimuli
What’s Osmosis?
net diffusion of water across a membrane
What is a hypertonic solution equal in terms of concentration?
Higher solute concentration; aka hyperosmotic; cells shrink
What does hypotonic solution equal in terms of concentration?
lower solute concentration; hypoosmotic; cells blow up
What does it mean if a solution is isotonic?
Both osmotic concentrations are equal; cells don’t change
What do aquaporins do?
facilitate osmosis
What is osmotic pressure?
the force needed to stop osmotic flow
What happens to water during extrusion?
it get ejected through contractile vacuoles
How much of sodium is moved out and how much potassium moves in during the Sodium-Potassium pump?
3 Na+ out, 2 K+ in
Does phagocytosis take in matter or fluid only?
matter only
Does pinocytosis only take in fluid or matter?
fluid
What’s endocytosis?
movement of substances into a cell
What’s exocytosis?
movement of substances out of a cell
Where are the integral membrane proteins embedded?
in the membrane
Where are peripheral proteins located?
the surface of the membrane
Out of the two, which is self recognized and which is tissue recognized?
Options are: Glycoproteins and glycolipids
1) Glycoproteins are “self”
2) Glycolipids are “tissue”
What’s a transmembrane domain?
when every membrane spans a region and is composed of hydrophobic amino acids arranged in alpha helices
What’s a B barrel?
a common feature of the porin class of proteins found w/in the outer membrane of some bacteria and are open on both ends; allow molecules to pass through the membrane
What’s a reticulon?
a wedge-shaped transmembrane protein that causes the membrane to bend
What’s passive transport?
when substances can freely move in and out of a cell w/o having to expend energy
What’s a concentration gradient?
the difference in concentration inside and outside of something
What’s diffusion?
a net movement go substances from regions of high concentration to low concentration
What are the 3 conditions that determine net movement of ions?
1) relative concentration on both sides of the membrane
2) voltage difference btw channels and membrane
3) state of the gate (open v. closed)
What’s membrane potential?
the voltage difference across the membrane
What’s an aqueous solution?
when cytoplasm in a cell had ions and molecules mixed with water
What’s a solute?
substances what’re dissolve in water (or other substances)
What’s osmotic concentration?
concentration of all solutes in a solution
If a solution has unequal concentrations, which one solute is hypertonic? Which one is hypotonic?
1) Hypertonic is one with higher concentration
2) hypotonic is one with lower concentration
How do you stop an organism from being hypertonic? (3 answers)
1) extrusion
2) isometric regulation
3) turgor
What’s active transport?
when cells use ATP to move substances up the concentration graident
How many types of molecules do uniporters transport?
one
How many types of molecules do symporters transport?
two
Do antiporters transport two molecules in the same direction or opposite directions?
opposite
What’s coupled transport?
the energy related as a molecule moves down the concentration gradient
What’s counter transport?
when substances bind to the same transport protein but on opposite sides
What’s receptor mediated endocytosis?
when molecules bind to specific receptors in plasma membrane and the cells carry them to their destination
How do large molecules and other bulky material enter and exit a cell?
Enter via endocytosis and exit via exocytosis
