Ch 7-- Diffusion across Plasma Membrane Flashcards
What two things make up the cell boundary?
Lipids (3 kinds) & proteins (2 kinds)
What are the three kinds of lipids?
Cholesterol, phospholipids, and glycolipids
What are the two kinds of proteins?
integral and peripheral
What makes up glycolipids?
carbs and lipids
What is selective permeability?
only certain molecules can come in and go out of the plasma membrane
What is a fluid mosaic model?
a montage of several proteins are embedded in a very fluid (mobile), phospholipid bilayer
Both phospholipid & membrane proteins can do what in the plasma membrane?
move freely within the bilayer
Is this lack of rigidity good or bad for the cell?
good, keeping processes in check such as Phagocytosis & cell signaling.
Phospholipid make up how much much of the plasma membrane
75%
An amphipathic molecule is made up of what?
hydrophilic and phobic structures
It is a hydrophobic…. with a….region.
head…polar
It is a hydrophilic…with a…region
tail…non-polar
Cholesterol makes up…and glycolipids make up…of the plasma membrane.
20%…5%
Cholesterol offers…
stability
Hydrophobic molecules can pass the membrane freely?
yes, (hydrocarbons) dissolve in the lipid bilayer
Hydrophilic molecules can pass through the membrane freely?
no, they need the help of a transport protein to act as a conduit
Where are integral proteins found? What do they function as?
They span the membrane from the inside to the outside. They function as transport proteins, enzymes, or receptors.
Where are Peripheral proteins found? What do they function as?
They are found on the surface of the plasma membrane. They function as enzymes & also play a role in cell-to-cell connections; DO NOT transport
What is concentration gradient?
It is the difference in concentration of a substance from one area to another & is usually studied across plasma membrane of a cell
Diffusion is the movement of a substance from a region of….to a region of….
High concentration…low concentration
Facilitated diffusion is diffusion with the help of a…
transport protein.
What is osmosis and which way does it diffuse?
It is the diffusion of water molecules across a selectively permeable membrane; it diffuses from a higher water concentrate to lower water concentrate.
The ability of a solution to cause a cell to gain or lose water is what?
tonicity
Hypertonic solution has a solute concentration… than that inside the cell=the cell…water.
greater…loses
Hypotonic solution has a solute concentration… than that inside the cell=the cell…water.
less…gains
Isotonic solution has a solute concentration is the…inside & outside of the cell= no net water moves across the membrane.
same
What are the two types of transport proteins?
channel and carrier
This transport protein acts as a gateway for molecules to pass through; ions/water goes down their concentration on gradient ex. aquaporin
channel
This transport protein bind to molecules & change shape to shuttle them across the membrane; polar molecules-sugars & amino acids
carrier
What are the two types of transport?
passive and active
This type of transport moves substances from high to low concentration & does so without any input of energy (does not require ATP); down conc. gradient
Passive
This type of transport moves substances from low to high concentration & with input energy in the form of ATP; goes against conc. gradient and requires ATP; ex: sodium-potassium pump/ proton pump.
Active
ATP pumps that contributes to a membrane potential are?
Electrogenic pumps
What and where is a sodium-potassium pump?
It transports 3 Na+ ions out of the cell & brings 2 K+ ions back into the cell for every cycle it runs. It is located in the plasma membrane (very active in nerve & muscular cells)
Electrical and Concentration gradient equals…. which drives diffusion of ions across the membrane.
Electrochemical gradient
What s co-transport?
depends on the ion gradient that the primary active created. once ions are on the other side of the membrane they fall down their conc. gradient (high to low)
….. is used by a cell for transport of macromolecules, polysaccharides & proteins, in membrane sacs called…..
Bulk Transport….. vesicles
Bulk transport requires ATP and is classified into 3 types:
endocytosis, exocytosis, and transcytosis
Endocytosis transport of substances….the cell.
into
…..transport of substance out of the cell.
exocytosis
Transcytosis transports……..of the cell
into, across & then out
Phagocytosis, Pinocytosis, and Receptor- mediated are the three types of…..
endocytosis
~”cell-eating”
~hydrolytic enzymes which were present in lysosome, start digesting the food after the formation of Phagolysosome
Phagocytosis
~”cell-drinking”
~ in the folds on the plasma membrane forms a vesicle & brings the extracellular fluid & the dissolved solutes into the cell
~the vesicle fuses with an endosome & the cell then absorbs the dissolved solutes present in the fluid
Pinocytosis
Receptor-mediated uses specific receptor proteins on a cell to……found outside the cell
bind molecules (ligand)
