________ have many different types of pore- like channel proteins in their membranes.
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Liposomes
________ provide a three- dimensional model that mimics a membrane- bound cell.
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Micelles
________ and phospholipid bilayers form spontaneously in water- no input of energy is required.
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Molecules
________ that contain only carbon and hydrogen are known as hydrocarbons.
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Vesicles
________ are small bubble- like structures consisting of lipid bilayers surrounding a small amount of aqueous solution.
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Gradients
________ are crucial to the function of the cell, in part because they make it possible for cells to engage in secondary active transport- also known as cotransport.
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hydrophobic regions
Substances that contain both hydrophilic and ________ are amphipathic.
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method
The ________ is called freeze- fracture electron microscopy because the steps involve freezing and fracturing the membrane before examining it with a scanning electron microscope (SEM), which produces images of an objects surface.
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Fatty acid
________ is a simple lipid consisting of a hydrocarbon chain bonded to a polar carboxyl functional group.
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Phospholipids
________ consist of a glycerol that is linked to a phosphate group and two hydrocarbon chains of either isoprenoids or fatty acids.
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Osmosis
________ occurs only when solutions are separated by a membrane that permits water to cross, but holds back some or all of the solutes- that is, a selectively permeable membrane.
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outside energy
When substances diffuse across a membrane in the absence of a(n) ________ source, it is known as passive transport.
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Singer
________ and Nicolson suggested that membranes are a dynamic and fluid mosaic of phospholipids and different types of proteins.
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glycerol
The ________ and fatty acid molecules become joined by what is called an ester linkage.
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Fats
________ are nonpolar molecules composed of three fatty acids that are linked to a three- carbon molecule called glycerol.
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Spontaneous movement of molecules
________ and ions is known as diffusion.
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movement of water
The ________ and K+ are examples of facilitated diffusion through channel proteins, but facilitated diffusion can also occur through specialized membrane proteins called carrier proteins.
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particular substance
Gated channels open or close in response to a signal, such as the binding of a(n) ________ or a change in the electrical voltage across the membrane.
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solute concentrations
If ________ are equal on both sides of the membrane, the outside is said to be isotonic.
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ester linkage
A(n) ________ occurs when two atoms (one of them carrying a double- bonded oxygen, often a carbonyl group) are linked together by an oxygen.
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Solutes
________ move randomly in all directions, but when a concentration gradient exists, there is a net movement from regions of high concentration to regions of low concentration.
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Hydrocarbon chains
________ that consist of only single bonds between the carbons are called saturated.
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Steroids a family of lipids
________ distinguished by the bulky, four- ring structure.
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electrical gradients
When considered together, concentration and ________ are called an electrochemical gradient.
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Selective permeability
________ means that some substances cross a membrane more easily than other substances do.
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active transport
Transport against a gradient is called ________.
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membranes permeability
A(n) ________ is closely related to its level of fluidity, which is a measure of molecular mobility.
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Micelles
________ tend to form from free fatty acids or other simple amphipathic lipids with single hydrocarbon chains.
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The movement of water is a special case of diffusion that is given its own name
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