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BIO 111 Chapter 5 Notes

Terms in this set (26)

Phospholipids are _________ molecules, containing hydrophobic and hydrophilic regions
amphipathic
The plasma membrane exhibits ____________, allowing some substances to cross it more easily than others
selective permeability
The _____________ states that the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
fluid mosaic model
The ___________ is one type of active transport system
sodium-potassium pump
occurs when active transport of a solute indirectly drives transport of other solutes
Cotransport
the cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
endocytosis
"cellular eating"
phagocytosis
"cellular drinking"
pinocytosis
Earl W. Sutherland suggested that cells receiving signals undergo these processes
*Reception
*Transduction
*Response
allows passage of hydrophilic substances across the membrane
Transport proteins
Channel proteins called __________ facilitate the passage of water
aquaporins
the tendency for molecules to spread out evenly into the available space
Diffusion
Substances diffuse down their ___________, from where it is more concentrated to where it is less concentrated
concentration gradient
The diffusion of a substance across a biological membrane is ___________ because no energy is expended by the cell to make it happen
passive transport
the diffusion of free water across a selectively permeable membrane
Osmosis
the ability of a surrounding solution to cause a cell to gain or lose water
Tonicity
Solute concentration is the same as inside the cell; no net water movement across the plasma membrane
Isotonic solution
Solute concentration is greater than that inside the cell; cell loses water
Hypertonic solution
Solute concentration is less than that inside the cell; cell gains water
Hypotonic solution
the control of solute concentrations and water balance, is a necessary adaptation for life in such environments
Osmoregulation
A plant cell in a hypotonic solution swells until the wall opposes uptake; the cell is now __________ (very firm)
turgid
If a plant cell and its surroundings are isotonic, there is no net movement of water into the cell; the cell becomes ___________ (limp) and the plant may wilt
flaccid
In a hypertonic environment, plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal effect called ___________
plasmolysis
transport proteins speed the passive movement of molecules across the plasma membrane
facilitated diffusion
Channel proteins include
*Aquaporins, for facilitated diffusion of water

*Ion channels that open or close in response to a stimulus (gated channels)
moves substances against their concentration gradients
Active transport
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