Questions and Answers
The presence of many C-C and C-H bonds causes fats to be...
The highlighted part of this molecule is derived from...
In fat synthesis, ________ and fatty acids combine to make fats plus ________.
In the reaction that builds a fat, ________ groups react with ________ groups.
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Triglycerides vary with respect to the number of...
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A food company hydrogenated a barrel of fat. The treatment...
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The most unsaturated fats have...
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What do DNA, proteins, and fats have in common?
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Which statement most accurately explains why cholesterol and phospholipids are amphipathic but fats are not?
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A phospholipid is a _____
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What region of a steroid is hydrophilic?
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Phospholipids and triglycerides both _____
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Lipids _____
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Steroids are considered to be lipids because they _____
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Molecules that are amphipathic must contain _____
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Lipids are insoluble in water because _____
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Which of the following is true of membrane lipids?
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In an experiment involving planar bilayers, what can you conclude if the right side tests negative for ions?
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Which aspect of phospholipids is most important to the formation of bilayers?
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Which of the following increases the strength of hydrophobic interactions in lipid bilayers?
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Which of the following crosses lipid bilayers the fastest?
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Which of the following crosses lipid bilayers the slowest?
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Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
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Decreasing the saturation of the fatty acid chains on a particular type of phospholipid would result in the formation of _____
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Which term best describes the type of membrane protein in the figure?
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For the study shown in the figure, what is the most appropriate control?
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Where would you most likely find an integral membrane protein?
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When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer. The best explanation for this is that _____
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When a membrane is freeze-fractured, the bumps seen on the fractured surface of the membrane are _____
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Study Notes
Lipids Overview
- Fats are rich in energy due to numerous C-C and C-H bonds and are insoluble in water.
- Phospholipids feature a hydrophilic head and a hydrophobic tail, making them amphipathic.
Fatty Acids and Glycerol
- Glycerol is derived from fatty acids, which are key components in fat synthesis where glycerol and fatty acids yield fats and water.
- Fats are formed through the reaction of hydroxyl and carboxyl groups.
Triglycerides
- Triglycerides differ in the number of carbon atoms and the presence of double bonds in their hydrocarbon tails.
Hydrogenation
- Hydrogenation of fats results in decreased fluidity and higher saturation levels, affecting the structure of fatty acid tails.
Unsaturated Fats
- The most unsaturated fats possess the highest number of double bonds, impacting their properties.
Common Features of Macromolecules
- DNA, proteins, and fats contain carbonyl groups, representing a shared molecular feature.
Amphipathic Molecules
- Cholesterol and phospholipids are amphipathic due to their dual hydrophilic and hydrophobic regions, unlike fats which are primarily hydrophobic.
- Molecules must contain both hydrophilic and hydrophobic regions to be classified as amphipathic.
Solubility and Permeability
- Lipids, including steroids, are characterized by their insolubility in water due to their nonpolar bonds.
- Membrane lipids are amphipathic, allowing for the formation of bilayers that regulate permeability to substances.
Membrane Structure
- Short, saturated hydrocarbon tails in phospholipids lead to less permeable membranes, counteracting the effects of tail length on permeability.
- When phospholipids and water are mixed, tiny vesicles filled with water may form upon mechanical shaking.
- Ions cannot cross planar bilayers, confirming the selective permeability of membranes.
Membrane Proteins
- Integral membrane proteins span across the bilayer, with portions exposed inside and outside the cell, contributing to membrane stability and function.
- Freeze-fracture studies reveal structural aspects of membranes, with bumps indicating the presence of integral proteins.
Molecular Movement
- Small nonpolar molecules, like oxygen (O2), pass through lipid bilayers rapidly, while ions such as sodium move across the bilayer slowly.
- The permeability of bilayers can be influenced by the saturation of fatty acid chains, with more fluid bilayers resulting from decreased saturation.
Experimental Controls
- In studies involving membrane properties, using a pure phospholipid artificial membrane can help isolate effects from experimental artifacts, confirming observed phenomena are attributable to lipid behavior.
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Description
Test your knowledge on lipids with these flashcards from Chapter 6 of Mastering Biology. Each card presents key concepts related to fats, glycerol, and their properties. Perfect for quick review and better retention of important biological terms.