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Biology Exam 2 Chap 7
N/A
35
Biology
Undergraduate 2
10/03/2011

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Term
What do we mean when we describe the plasma membrane as a fluid mosaic?
Definition
it is fluid lipid component - flexible and dynamic phospholipid bilayer. separates cell from external environment
mosaic of proteins which allow cell to interact with environment - only certain substances can cross
Term
What types of lipids are in plasma membrane?
Definition
phospholipids with cholesteral
Term
Integral Proteins
Definition
penetrate hydrophobic core of lipid bilayer
transmembrane - proteins cross entire membrane
Term
Peripheral Proteins
Definition
are not embedded in bilayer but loosely bound to surface
Term
The bilayer is a double layer of what type of molecule?
Definition
???
Term
Transport Proteins
Definition
specific for the substance
some passive/some active
can be hydrophilic
carriers change shape and shunt molecules across
ex. cystic fibrosis
Term
Enzymatic Proteins
Definition
speed up chemical reactions
active site on one side of the membrane
sometimes in groups
ex. ATP synthase
Term
Signal Transduction Proteins
Definition
receptor proteins with binding site for specific signal molecule - leads to some cellular change
ex. growth hormone receptor
Term
Recognition Proteins
Definition
glycoproteins that identify cells as being certain type of cell or from individual
cell to cell recognition
ex. MHC proteins
Term
Intercellular Joining Proteins
Definition
membrane proteins of adjacent cells join together forming junctions
ex. intestinal cells
Term
Proteins for Attachment to cytoskeleton & extra cellular matrix
Definition
bind to cytoskeletal proteins within cell and anchor them in place
or adhere to extra cell. matrix outside cell connecting them to tissues
Term
What is the role of carbohydrates in cell recognition?
Definition
cell to cell recognition
varies by species, ind of a species, tissues in the ind, cells in the ind.
Term
Selective Permeability
Definition
cells regulation of what substances cross the plasma membrane - depends on the type and distribution of membrane lipids and proteins, the polarity, the size
Term
How do active and passive membrane transports differ?
Definition
passive does not require energy
active requires energy input from atp
Term
Concentration Gradient
Definition
when two areas exist with different concentrations of a substance
Term
How does a concentration gradient “go down”?
Definition
when molecules move from high concentration to low concentration
Term
How does a solution go against the concentration gradient?
Definition
requires energy
molecules move from low con. to high con.
Term
Diffusion
Definition
movement of molecules from area of high con. to low con. due to random molecular motion (spontaneous) - eventually reaches equilibrium where molecules are evenly distributed
passive transport
Term
Osmosis
Definition
diffusion of water across semi permeable membrane through tiny aquaporins
passive, down the gradient
Term
Hypertonic Solutions
Definition
greater concentration of solute than the otherHy solution
when cell is in hyper. solution water will exit cell - cell will shrink
Term
Hypotonic Solution
Definition
lower concentration of solute than the other solution
when cell in in hypo. solution water will enter cell - cell will swell
Term
Isotonic Solutions
Definition
solutions have the same concentration of solute as another solution
when cell is in isot. solution there is no net movement of water - cell will maintain its shape
Term
How do animal cells react in hypertonic and hypotonic solutions?
Definition
hypertonic - cells will shrivel
hypotonic- cells will burst
Term
How do plant cells react in hypertonic and hypotonic solutions?
Definition
Hypertonic - cells will become plasmolyzed - pm and cell contents pull away from cell wall
Hypotonic - cells will become turgid
Term
Facilitated Diffusion
Definition
type of diffusion facilitated by transport proteins
ions are transported across membrane by channels or carrier proteins
does not require energy, passive, molecules go down in concentration gradient
Term
How does water cross the plasma membrane?
Definition
osmosis (diffusion of water) through aquaporins
Term
Bulk Passage
Definition
VESICLES used to move large molecules or particles in or out of cell
active process - requires ATP to move vesicles
endocytosis - vesicles taken into cell
exocytosis - vesicles taken out of cell
Term
Endocytosis
Definition
vesicles taken into cell
Term
Exocytosis
Definition
vesicles taken out of cell
Term
How do phagocytosis and pinocytosis differ?
Definition
phagocytosis - engulfing of SOLID particles
pinocytosis - engulfing of LIQUID substances
Term
What is the difference between facilitated and active transport?
Definition
facilitated uses proteins
active uses ATP
Term
How does receptor mediated Endocytosis differ from regular endocytosis?
Definition
allows cell to engulf LARGE quantities of SPECIFIC substances
coated pits on the plasma membrane of cell which are lined with receptors for specific substance
Term
Passive Membrane Transport
Definition
does not require energy transport
2 areas exist with different concentrations of a substance (concentration gradient)
molecules move from high concentration to low concentration (going down on concentration gradient) due to random molecular motion
ex. diffusion
Term
Active Membrane Transport
Definition
requires energy from ATP
carriers move molecules across membrane
molecules moved against the gradient
Term
Sodium Potassium Pump
Definition
pumps Na+ outside of cell and K+ inside of cell - - produces chemical gradient
produces internal environment very different from external environment
active transport, against gradient
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