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The container is the _________ _____- a protein-studded, fatty film so thing that it cannot be seen directly in the light microscope.
_____ ______ enclose intracellular membranes.
The lipid bilayer serves as a _____ ______ to most water-soluble molecules.
The _____ carry out functions of the membrane.
- Plasma membrane
- Internal membranes
- Permeability barrier.
How is the structure of cell membranes determined by?
Membrane lipids form________ in water.
The most abundant lipids in cell membrane are t he _________, which have a phosphate-ciontaining, hydrophilic head linked to a pair of hydrophobic tails.
_____________ has the small molecule choline attached to a phosphate group as its hydrophilic head.
The way membrane lipids behave in a watery (aqueous) environment.
Where is cholesterol found?
Fat is found in what creatures cells?
What are animal fats?
Oils are found in what?
The formation of a lipid bilayer satisfies what two forces?
- Animal cell membranes
- Plant seeds.
- Hydrophilic of phosphate group and hydrophobic of lipid group.
What happens if the tear in a lipid bilayer is large?
The only way to avoid having free edges is to what?
The lipid bilayer will fold onto itself and break up into separate closed vesicles.
Bend and seal, forming a boundary around a closed space which is why amphipathic molecules assemble into self-sealing containers.
What two behaviors are crucial to lipid bilaryers?
Pure phospholipids will form closed vesicles, called _______.
- 1. Flexibility allowing ability to bend.
- 2. Two-dimensional fluidity.
Lipid molecules continuously exchange places with their ______ in the same monolayer.
What diffusion type is it?
Lipid molecules not only flex their hydrocarbon tails, they also do what?
- Lateral diffusion.
Rotate rapidly about their long axis.
The fluidity of a lipid bailer depends on its what?
What happens when the tails are closer and more regularly packed?
What are two major properties of hydrocarbon tails that affect how tightly they pack in the bilayer?
- 1. Composition
- 2. Phospholifpid composition or nature of hydrocarbon tails.
- The more viscous and less fluid the bilayer will be.
Length of tail and number of double bonds.
In animals membrane fluidity is modulated by the inclusion of the sterol ___________.
Four important reason of why membrane layers are important.
- 1. Enables membrane proteins to diffuse rapidly in the plane of the bilayer and to interact with one another, cell signaling.
- 2. Permits entry of lipids and proteins in to the cell.
- 3. Fusion.
- 4. Distribute evenly during division.
Where does membrane assembly begin?
New phospholipids are manufactured by what?
Most cell membranes are asymmetrical: how?
Process of membrane making.
- In the ER.
- Enzymes bound to the cytosolic surface of the endoplasmic reticulum.
Two halves of the bilayer often include different sets of phospholipids.