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BIOLOGY EXAM 2 CHAPTER 7
CHAPTER 7 NOTES
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Biology
10/01/2012

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Term

1) plasma membrane

2) plasma membrane

3) plasma membrane

4) selective permeability

 

Definition
The _____ _______ is the edge of life, the boundary that seperates the living cell from its surrounding. A remarkable film only about 8 nm thick, it would take over 8,000 plasma membranes to equal the thickness of this page--the _____ ________ controls traffic into and out of the cell it surrounds. Like  all biological membranes, the _____ _______ exhibits __________ _________ that is, it allows some substances to cross it more easily than others.
Term

1) phospholipids

2) phospholipids

Definition
The most abundant lipids in most membranes are ___________. The ability of _______ to form membranes is inherent in their molecular structure.
Term

1)amphipathic

2)amphipatic

Definition
A phospholipid is an _______ molecule, meaning it has both a hydrophilic region and a hydrophobic region. Other types of membranes are also ________. Futhermore, most of the proteins within membranes have both hydrophobic and hydrophilic regions
Term
Fluid Mosaic Model 
Definition
How are phospholipids and proteins arranged in the membranes of cells? In the ___ ____ ____, the membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a double layer (bilayer) of phosphlipids.
Term
hydrophobic
Definition
A membrane is held together primarily by ________ interactions, which are much weaker than covalent bonds.
Term

1)Fluid

2)Fluid

3)Fluid

Definition
Membranes must be ____ to work properly; they are usually about as ___ as salad oil. When a membrane solidifies, its permeability changes, and enzymatic proteins in the membrane may become inactive if their activity requires them to be able to move within the membrane. However, membranes that are too ___ cannot support protein function either. 
Term
Peripheral Proteins
Definition
Not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to expose parts of intergral proteins. 
Term

1) Integral Proteins

2)Integral

3)amino acids 

Definition
Penetrate the hydrophobic interior of the lipid bilayer. The majority are transmembrane proteins, which span the membrane, other ____ proteins extend only partway into the hydrophobic interior. The hydrophobic regions of an ______ protein consist of one or more stretches of nonpolar _____ ____ usually coiled into helices.
Term

1) cytoskeleton

2) extracellular matrix

Definition
On the cytoplasmic side of the plasma membrane, some membrane proteins are held in place by attachment to the ____________. And on the extracellular side, certain membrane proteins are attached to fibers of the ___________ ____.
Term

Transport 

1) channel

2) transport

3)ATP

 

Definition
A protein that spans the membrane may provide hydrophilic ____ across the membrane that is seletive for a particular solute. Other ____ proteins shuttle a substance from one side to the other by changing shape. Some of these proteins hydrolyze __ as an energy source to actively pump substances across the membrane 
Term

1) enzyme

2) enzyme

Definition
A protein built into the membrane may be an _____ with its active site exposed to substances in the adjacent solution. In some cases, several ____ in a membrane are organized as a team that carries out sequential steps of a metabolic pathway
Term

1)hormone

2)cell

3)cytoplasmic

Definition
A membrane protein may have a binding site with a specific shape that fits the shape of a chemical messenger such as a ______. The external messenger may cause the protein to change shape, allowing it to relay the message to the inside of the __, usually by binding to a _________ protein. 
Term

1)cytoskeleton

2)shape

3)ECM

4)extracellular

5)intracellular

Definition
Microfilaments or other elements of the ________ may be noncovalently bound to membrane proteins, a function that helps maintain cell ____ and stabilized the location of certain membrane proteins. Proteins can that bind to ___ molecules can coordinate ________ and _______ changes.
Term

1)cell-cell recognition (whole definiton)

2)foreign

3)recognize

4)carbohydrates

Definition
A cell's ability to distinguish one type of neighboring cell from another, is crucial to the functioning of an organism. It is also the basis for the rejection of _____ cells by the immune sustem, an important line of defense in vertebrate animals. Cells _____ other cells by binding to molecules, often containing _________, on the extracellular surface of the plasma membrame 
Term

1)glycolipids

2)glycoproteins

Definition
Membrane carbohydrates are usually short, branched chains of fewer than 15 sugar units. Some are covalently bonded to lipids, forming molecules called __________. However, most are covalently bonded to proteins, which are thereby __________.
Term

1)hydrocarbons

2)carbon dioxide

3)oxygen

4)membrane

Definition
Nonpolar molecules, such as ______, ____ ______, and _____, are hydrophobic and can therefore dissolve in the lipid bilayer of the membrane and cross it easily without the aid of _______ proteins. 
Term

1)ions and polar

2)Polar

3)polar

Definition
The hydrophobic interior of the membrane impedes the direct passage of ____ and ___ molecules, which are hydrophilic, through the membrane. ____ molecules such as glucose and other sugars pass only slowly through the lipid bilayer, and even water, an extremely small ____ molecule, does not cross very rapidly. 
Term

1)ATP

2)ATP

3)phosphate

4)shape

5)sodium-potassium pump

6)Na+ for K+

Definition
___ suppiles the energy for most active transport. One way ___ can power active transport is by transferring its terminal ________ group directly to the transport protein. This can induce the protein to change its ___ in a manner that translcates a solute bound to the protein across the membrane. One transport system that works this way is the _____-________ ____, which exchanges ___ for ___ across the plasma membrane of animal cells. 
Term
1)Charged
Definition

A _____ atom or molecule and its surrounding shell of water find the hydrophobic interior of the membrane even more difficult to penetrate. 

Term
1)Transport Proteins 
Definition
Cell membranes are permeable to specfic ions and a variety of ___ molecules. These hydrophilic substances can avoid contact with the lipid bilayer by passing through _____ _____ that span the membrane 
Term
1)Channel Proteins 
Definition
Some transport proteins, called _____ ____, function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane
Term
Aquaporins
Definition
The passage of water molecules through the membrane in certain cells is greatly facilitated by channel proteins knows as 
Term

1) Permeases (whole definiton)

2)Carbon Dioxide

Definition

Membrane bound proteins that facilitate the movement of molecules across the membrane, categorized by energy use. (molecules that are not permeable or that move slowly) large or charged molecules.

_______ ________ will always pass because it is small and non polar 

Term
Membrane Potential 
Definition
The voltage across a membrane is called a _______ _____. It acts like a battery, an energy souce that affects the traffic of all charged substance across the membrane. 
Term

1)negative

2)cations

3)anions

Definition
Because the inside of the cell is _______ compared with the outside, the membrane potential favors the passive transport of ____ into the cell and _____ out of the cell. 
Term

1)size and shape

2)lipids

3)chemical

Definition

Factors involved in the permeability:

____ and ____ of molecules

solubility in ____

net electric charge

______ properties

 

Term
Water 
Definition
The universal solvent in biological systems that moves freely across the membrane
Term
Diffusion
Definition
The movement of molecules of any substance so that they spread out evenly into the available space. Individual molecules move randomly, but the net movement is not random. Does not need protein to move, any that is permeable.
Term

1)Concentration Gradient

2)Spontaneous

3)Concentration Gradient

Definition
Any substance will diffuse down its ___________ _____, the region along which the density of a chemical substance increases or decreases. No work must be done to make this happen; diffusion is a _________ process, needing no input of energy. *Each substance diffuses down its own __________ _____, unaffected by the gradients of other substances 
Term
Molecules move from a place of high concentration to a place of low concentration. From high free energy to low free energy. They release energy to cell. 
Definition
What force causes the net movement?
Term

1)passive transport

2)potential

3)diffusion 

Definition
The diffusion of a substance across a biological membrane is called _____ _____ because the cell does not have to expend energy to make it happen. The concentration gradient itself represent _______ energy and drives diffusion. Remember, however, that membranes are selectively permeable and therefore have different effects on the rates of _____ of various molecules.
Term

1)lower

2)higher

3)higher

4)lower

5)equal

 

Definition
Water diffuses across the membrane from the region of _____ solute concentration (____ free water concentration) to that of a ____ solute concentration (____ free water concentration) until the solute concentrations on both sides of the membrane are _____.
Term
Osmosis
Definition
The diffusion of free water across a selectively permeable membrane, where aritifical or cellular, is called ____. The movement of water across cell membranes and the balance of water between the cell and its environment is crucial to organisms.
Term

1)Tonicity (whole definiton)

2)water

Definition
the ability of a surrounding solution to cause a cell to gain or lose water. Depends in part on its concentration of solutes that cannnot cross the membrane relative to that inside the cell. If there is a higher concentration of nonpenetrating solutes in the surrounding solution, ____ will tend to leave the cell, and vice versa 
Term

1) isotonic

2)no

3)isotonic

4)equal

Definition
If a cell without a wall, such as an animal cell is immersed in an environment that is _____ to the cell; there will be __ net movement of water across the plasma membrane. Water diffuses across the membrane, but at the same rate in both directions. In a _______ environment, the voulme of an animal cell is stable. (______ concentration)
Term
Hypertonic
Definition
If a cell is transferred to a solution that is _____ (more concentrated) to the cell, the cell will lose water, shrivel, and probably die. (water leaves the cell)
Term
Hypotonic
Definition
If a cell is placed in a solution that is _____ (less concentrated) to the cell, water will enter the cell faster than it leaves and the cell will swell and burst. 
Term
Facilitated Diffusion
Definition
Many polar molecules and ions impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane. This phenomenon is called _________ _______
Term

1) Channel

2)hydrophilic

Definition
______ proteins simply provide corridors that allow specific molecules or ions to cross the membrane. The ________ passageways provided by these proteins can allow water molecules or small ions to diffuse very quickley from one side of the membrane to the other.
Term

1) ion

2) ion

Definition
Channel proteins that transport ions are also called ___ channels. Many ___ channels function as gated channels which open and close in response to a stimulus. 
Term

1)carrier

2)carrier

3)concentration gradient

4)passive transport

Definition
______ proteins, such as the glucose transporter mentioned earlier, seem to undergo a subtle change in ____ that somehow translocates the solute-binding site across the membrane. ______ proteins are involved in facilitated diffusion that result in the net movement of a substance down its _____________ _____; no energy input is required, this is _______ ______
Term
Facilitated diffusion
Definition
_________ ______ speeds transport of a solute by providing efficient passage through the membrane, but it does not alter the direction of transport 
Term

1) Active transport 

2)against

3)carrier 

Definition
To pump a solute across a membrane against its gradient requires work; the cell must expend energy. Therefore, this type of membrane traffic is called _____ ______. The transport proteins that move solutes _____ their concentration gradients are all _____ proteins rather than channel proteins. This makes sense because when channel proteins are open; they merely allow solutes to diffuse down their concentration gradients rather than picking them up and transporting them against their gradients.
Term
Active Transport 
Definition
_____ ______ enables a cell to maintain internal concentrations of small solutes that differ from concentrations in its environment. 
Term

1)Diffusion

2)Chemical

3)Electrical

4)electrochemical gradient

Definition
Two forces drive the _____ of ions across a membrane: a ______ force (ion's concentration gradient) and an _____ force (the effect of the membrane potential on the ion's movement). This combination of forces acting on an ion is called the __________ _______.
Term

1)exocytosis

2) fuse

3) spill

Definition
When a cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane; this process is called ________. A transport vesicle that has budded from the golgi apparatus moves along microtubules of the cytoskeletom to the plasma membrane. When the vesicle membrane and plasma membrane come into contact, specific proteins rearrange the lipid molecules of two bilayers so that the two membranes ____. The contents of the vesicles then ____ outside of the cell.
Term
Endocytosis
Definition
In _______, the cell takes in biological membranes and particulate matter by forming new vesicles from the plasma membrane. The events of _______ look like the reverse of exocytosis. 
Term
Phagocytosis
Definition
(type of endocytosis) A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membranous sac called a food vacuole. The particle will be digested after the food vacuole fuses with a lysosome containging hydrolytic enzymes
Term
Pinocytosis
Definition
(type of endocytosis) the cell "gulps" droplets of extracellular fluid into tiny vesicles. It is not the fluid itself that is needed by the cell, but the molecules dissolved in the droplets. Because any and all included solutes are taken into the cell, ________ is nonspecific in the substances it transports 
Term
Definition