Biology Chapter 7
increases or decreases membrane fluidity depending on temperature
cholesterol
provide corridors that allow a specific molecule or ion to cross the membrane
channel protein
the ion's concentration gradient
chemical force
the 2 combined forces that drive the diffusion of ions across a membrane
chemical force and electrical force
integral proteins that span the membrane
transmembrane proteins
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly
embedded in a lipid bilayer
water will move to an area of ...
greater solute concentration
movement of water across a membrane
osmosis
phospholipids flip flop...
1 time per month
how facilitated diffusion differs from simple diffuison
1. require protein to act as carrier 2. protein only allows transport of specific molecule/ion 3. rate of transport can be saturated
phospholipids move laterally...
10^7 times per second
requires an energy investment for molecule movement
active transport
requires energy; movement of molecules against concentration gradient; moves molecules in only 1 direction; requires membrane protein called a pump
active transport
containing both hydrophilic and hydrophobic regions
amphipathic
channel proteins in the plasma membrane which permit the passage of water
aquaporins
undergo a subtle change in shape that translocates the solute binding site across the membrane
carrier protein
help maintain water balance in plants
cell wall
active transport of a specific solute indirectly drives the active transport of another solute; active transport driven by a concentration gradient
cotransport
using active transport to pump a solute against its concentration gradient only to have it diffuse back along with a solute that is moving against its own concentration gradient
cotransport
at a high temperature, cholesterol...
deceases membrane fluidity
the tendency for molecules of any substance to spread out evenly into the available space
diffusion
the effect of the membrane potential on the ion's movement
electrical force
movement of materials into a cell by forming new vesicles from the plasma membrane
endocytosis
as temperatures cool, membranes switch from _____ state to _____ state
fluid; solid
phospholipids in the plasma membrane...
exhibit constant lateral movement
transport vesicles migrate to the plasma membrane, fuse with it, and release their contents
exocytosis
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most likely functioning in the intestinal cells?
facilitated diffusion
channels will allow the movement of a specific molecule or ion
facilitated diffusion
transport proteins speed the movement of molecules across the plasma membrane; movement of ions and polar molecules; net movement from area of high concentration to low concentration
facilitated diffusion
cellular membranes are ______ of lipids and proteins
fluid mosaics
the type of _______ in phospholipids affects fluidity of the plasma membrane
hydrocarbon tails
molecules that are lipid soluble and can pass through the membrane rapidly
hydrophobic molecules
the concentration of solutes is greater; cell will lose water
hypertonic
the concentration of solutes is less; cell will gain water
hypotonic
at a low temperature, cholesterol...
increases membrane fluidity
proteins that penetrate the hydrophobic core of the membrane
integral proteins
the sodium-potassium pump...
is phosphorylated to cause a structure change
the concentration of solutes is the same; no net movement of water
isotonic
in hypotonic environments, animal cell is
lysed
in isotonic environments, animal cell is
normal
the control of water balance; is a necessary adaptation for life
osmoregulation
transport of water molecules across a membrane
osmosis
diffusion across a membrane with no input of energy
passive transport
proteins bound to the surface of a membrane
peripheral protein
cell eating
phagocytosis
most abundant lipid in plasma membrane
phospholipid
cell drinking
pinocytosis
the process whereby a plasma membrane brings fluid and solute molecules from the extra cellular environment into the cell by pulling the plasma membrane in and forming a vesicle
pinocytosis
molecules that do not cross the membrane rapidly
polar molecules
protein docking sites
receptor-mediated endocytosis
in hypertonic environments, animal cell is
shriveled
movement of small non-polar molecules such as CO2
simple diffusion
passive transport, small lipid-soluble molecules pass, net movement is down the concentration gradient
simple diffusion
movement of solute molecules from an area of high concentration to an area of low concentration
simple diffusion and facilitated diffusion
cholesterol is considered a...
temperature buffer
when a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?
the cell will become turgid
ability of a solution to cause a cell to gain or lose water
tonicity
allows for the passage of hydrophilic substances across a membrane
transport proteins
(T/F) cholesterol is embedded in the plasma membrane; it can make the membrane less fluid in higher temperatures and more fluid in lower temperatures
true
(T/F) phospholipids can move within the bilayer
true
