Chapter 7 - Membrane & Structure Function Flashcards
what are amphipathic molecules (ex:phospholipids)
contains hydrophobic and hydrophilic regions
the fluid mosaic model
the membrane structure depicted as a pmosaic of protein molecules, bobbing in a fluid bilayer of phospholipids.
are proteins randomly distributed in the membrane?
no, they form groups
membranes are held together by _ interactions
weak hydrophobic interactions
unsaturated tails are fluid ->
they prevent packing
saturated tails are viscous->
the tails pack together
at lower temperatures, cholesterol ->
disrupts packing, hindering solidification
peripheral proteins
proteins that are bound to the surface of the membrane
integral proteins
proteins that penetrate the hydrophobic core
a biological membrane is…
two layers of phospholipids with proteins either spanning the layers or on the surface of the layers (think of the fluid mosaic model)
transmembrane proteins are…
integral proteins that span the membrane
selective permeability
membranes may be selective, some substances cross more easily than others
the movement of particles of any substance so that they spread out evenly into the available space
diffusion
the diffusion of a substance across a biological membrane (no additional energy is required)
passive transport (does not need energy to cross membrane)
what is osmosis ?
the diffusion of free water, across a selectively permeable membrane
water molecules will diffuse in order to…
water molecules regulate the solute concentration on both sides (in the tube case, moves from lower concentration to higher concentration to balance)
a hypotonic cell is
more water in the cell, appears bigger
a isotonic cell is
normal balance of water going in and out, cell is normal
a hypertonic cell is
lacks water, appears shriveled
facilitated diffusion is…
passive transport aided by proteins
channel proteins
type of protein that has a hydrophilic channel that can be used as a tunnel
carrier proteins
a protein that BINDS to the molecules + changes shape to shuttle them across the membrane
transport proteins are…
a type of protein that moves only specific substances (selective permeability depends on the specific type of transport protein)
what is active transport?
using energy to move substances against their gradients
all proteins in active transport are…
they are carrier proteins (they have to bind and change shape)
facilitated diffusion is different from active transport because of…
F.D. goes along with the gradient (not require energy), active goes against (uses energy
bulk transport
large molecules being transported by exocytosis and endocytosis
in exocytosis
bulk transport, transport vesicles migrate to the membrane + fuse and export contents outside cell
in endocytosis
macromolecules are taken into the cell, makes a pocket around it
the three types of endocytosis
phagocytosis (eats + pocket), pinocytosis (drinks + coats, and receptor mediated (coated vesicle + binding to receptors)
