Biology-Lipids

12 September 2022
4.7 (114 reviews)
35 test answers

Unlock all answers in this set

Unlock answers (31)
question
Which of these classes of biological molecules does NOT include polymers?
answer
Lipids; fats are NOT polymers but they are large molecules assembled from small ones- glycerol and fatty acids
question
The characteristic that all lipids have in common is that _____.
answer
none of them dissolves in water
question
Which of these is NOT a lipid?
answer
RNA; Are lipids: wax, steroids, cholesterol, phospholipids
question
What do unsaturated fatty acid tails lack?
answer
Double bonds
question
Which of these is rich in unsaturated fats?
answer
olive oil; one or more bonds with one fewer hydrogen; liquid at room temperature
question
A function of cholesterol that does not harm health is its role _____.
answer
Cholesterol is an important component of animal cell membranes.
question
The presence of many C-C and C-H bonds causes fats to be ...
answer
The many C-C and C-H bonds make fats nonpolar and insoluble in water. They can also be oxidized, releasing much energy.
question
In fat synthesis,________and fatty acids combine to make fats plus________.
answer
glycerol;water
question
In the reaction that builds a fat,________ groups react with ________ groups.
answer
hydroxyl; carboxyl Fatty acids supply the carboxyl groups; the hydroxyls come from glycerol.
question
Fats vary with respect to the number of ...
answer
C atoms in the tails. and double bonds in the tails. Tail lengths of 16 to 22 are common. There may be from 0 to 6 double bonds.
question
A food company hydrogenated a barrel of fat. The treatment ...
answer
Hydrogenation removes double bonds, so the tails can straighten. Do you know why that makes the fats less fluid?
question
The most unsaturated fats have ...
answer
the most double bonds. Every double bond is a place where hydrogen could be added.
question
What do DNA, proteins, and fats have in common?
answer
They contain carbonyl groups.
question
Which of the following statements concerning unsaturated fats is true?
answer
They have double bonds in the carbon chains of their fatty acids.
question
What do fats, steroids, and waxes have in common?
answer
Low solubility in water.
question
Dr. Haxton told one of his students, "To move in the bloodstream, fats need the help of phospholipids." What would a good student say?
answer
Yes. Nonpolar molecules aren't compatible with water. Water rejects nonpolar molecules such as fats, so fats travel inside particles that are coated with polar parts of phospholipids and proteins.
question
Phospholipids are most important for ...
answer
preventing leakage from cells. Every cell depends on phospholipid bilayers to limit leakage of molecules through membranes.
question
To find the best source of phospholipids, look at ...
answer
membranes; The great majority of a cell's phospholipids occur in membranes.
question
What do phosphoglycerides and fats have in common?
answer
Ester linkages; Like fats, phosphoglycerides are made by coupling fatty acids to glycerol by means of ester linkages.
question
Which statement is true of phospholipids?
answer
Their synthesis uses fatty acids, Some of their tails have double bonds and They all ioniz
question
Which fact is most important in causing phospholipids to behave as they do in water?
answer
Water molecules make hydrogen bonds; The hydrogen bonds in water exclude the nonpolar tails of phospholipids, forcing the molecules into a bilayer.
question
In a membrane, the________of the phospholipids in one monolayer face the________of the phospholipids in the other monolayer.
answer
tails; tails Water on both sides of the membrane excludes the tails, forcing them into the interior where they face one another.
question
It is difficult for molecules to pass through the phospholipid bilayer because ...
answer
polar molecules attract one another. Polar molecules have trouble escaping from the water to enter a membrane, and nonpolar molecules have trouble moving from the membrane into water. Thus, neither kind of molecule moves easily through membranes.
question
Which lipid is most amphipathic?
answer
Phospholipid A phospholipid has a strongly polar (charged) head and two nonpolar tails.
question
The molecule shown here probably ... (phospolipid)
answer
is structurally related to a fat, is highly amphipathic and is made partly from fatty acids. Phospholipids are close relatives of fats, but the difference makes them amphipathic and allows them to form the basis of membranes. Important stuff!
question
How do phospholipids interact with water molecules?
answer
The polar heads interact with water; the nonpolar tails do not.
question
Steroids are considered to be lipids because they _____.
answer
are NOT soluble in water
question
What does cholesterol have in common with sex hormones?
answer
Four linked rings
question
For good health, you don't want your body to run the LDL part of this diagram faster than the HDL part because ...
answer
LDL cholesterol is stored; HDL cholesterol is destroyed If LDL exceeds HDL, your body is probably storing excess cholesterol, which may clog the arteries and cause heart disease.
question
What is the function of Structure E? (Cholesterol)
answer
stabilization of the phospholipids
question
Identify Structure A. (glycoprotein) How can you tell?
answer
It is composed of both a carbohydrate and a protein.
question
Which of the following is least likely to be important in holding the components of a biological membrane together?
answer
covalent interactions between the phospholipid and protein components of the membrane This is not an important interaction because there are rarely covalent bonds between the phospholipids and integral membrane proteins.
question
Things important in holding the components of a biological membrane together?
answer
-polar interactions among the phospholipid head groups on the same surface of the membrane -hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane -hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane -hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane
question
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures?
answer
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
question
In what way do the membranes of a eukaryotic cell vary?
answer
Certain proteins are unique to each membrane.