Biology Chapter 7

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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


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