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42 Cards in this Set
- Front
- Back
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What is the structure of a fatty acid? |
Carboxyl group head O-C=O (single bonded O is negative)
Hydrocarbon tail |
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Amphipathic |
Has both hydrophilic and hydrophoic properties |
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How are triglycerides formed? |
Glycerol binds to three fatty acids via esterfication.
There OH groups bind, and 3 water molecules are released in the process |
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What is a phospholipid? |
A triglyceride where one of the fatty acids is replaced with a
O II O -P- OH I OH |
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What is the basis of a cholesterol? |
3 hex-rigns and a pent ring directly attatched |
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What is the function of vitamin D? |
Contributes greatly to membrane fluidity
Precursor of steroid hormones
Precursor of vitamin D
Precursor of bile acids |
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What is a micelle? |
A sphirical collection of fatty acids, with the hydrophyilic heads pointing out and the hydrophobic tails hidden in the middle. |
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What is a liposome? |
A fatty acid bilayer; the tails of two layers touch. The inner carboxyl heads trap water with in the liposome, while the outer heads keep it out. |
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What are integral membrane protiens? |
transmembrane proteins that strongly interact with the phospholipid tails |
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What are peripheral membrane proteins? |
Do not span the membrane, but are bound to it by many means |
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What fatty acid is coded 18:2 (delta 9,12)? |
Linoleic acid |
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What fatty acid is coded 18:1 (delta 9)? |
Oleic acid |
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List three substances derived from fatty acids? |
Wax, Leukotrienes, Sphingolipids, Triglycerides |
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What dose the esterficaton of glycerol with three fatty acids produce. |
Triglycerol |
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What is the precursor to prostaglandins? |
Fatty acids |
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Why are trans-fats found in food? |
Both cis and trans isomers are made during the chemical reduction (hydorgenation) of fats in food production. |
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Is cholesterol found in bacteria? |
Yes, but only rarely |
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What is the most uncommon way for things to mover around a lipid bilayer without enzymes? |
Flipping from one side to the other |
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How is faciliated diffusion through a membrane accomplished? |
With special protien ports, but the movement is driven by concentration |
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What are the common properties of membrane proteins? |
May have covalently attatched proteins and carbs
can diffuse latteraly in the membranes
made of the same 20 ammino acids |
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What is delta notation? |
Designates the postion of the first carbon involved in a double bond.
The carboxyl group is always carbon 1 |
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What is a polyunsaturated fatty acid? |
a fatty acid with multiple double bonds. |
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In a fatty acid double bond what are the two ways the hydrogens attateched to the double bond can be arranged? |
Cis: on the same side, forms a kinked carbon chain.
Trans: on opposite sides, forms a straight carbon chain |
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What is the effect of being Cis or Trans on melting point? |
Cis: do to the kinks fatty acids cannot pack tightly, and so have lower melting points, tending to be fluid at room temprature.
Trans (and saturated): Have straight chains that pack tightly, resulting in high melting points, they tend to be solid at room temperature. |
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What is the difference between Isolated and conjugated double bonds? |
Isolated double bonds have are single bonded to an atom which is single bonded to another double bond (C=C-C-C=C) There electron clouds have no over lap with each other making them more reactive.
Conjugate double bonds are bound directly together with a single bond (C=C-C=C) do to the over lap of their electron clouds, there is little room for other molecules to get in react, making them less reactive.
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Why are oils yellow? |
This is due to a reaction of the isolated double bonds with oxygen and light.
Cells have antioxidents to keep this from happening to their membranes. |
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What is the pKa of the fatty acid carboxyl group, and how dose this impact it's role in membranes? |
It's a weak acid with a pKa of 4.8, meaning that at the physiological pH of 7 it is always dissociated into -coo. This makes it very hydrophilic, which is the primary factor in forming the lipid bilayer. |
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How are triglycerides formed? |
3 fatty acids esterfied to a glycerol (looks like the letter E)
Fatty acids bound to glycerol via an oxygen single bound between them.
3 water molecules are realeas when this molecule is formed. |
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How dose triglyceride react with water? |
It is very hydrophobic, as the ester bonds do no H-bond with water.
This is good, because it helps keep the weight of stored fat down. |
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Why are the carbohydrates used for energy storage in plants heavier than lipids in mammals? |
Carbohydrates have more oxygen atoms. |
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Where in the body are more or less saturated stored fats found? |
More saturated, denser visceral fat is found with in the body cavity closer to the organs.
Less saturated, squishier fat is found under the skin and is called subcutaneous fat. |
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What makes phosopholipids so polar? |
The phosphatidic acid esterfied to the third position in a triglyceride. |
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What are the pKa values of phosphatidic acid and why are they important? |
It actually has three; one at pH 2, another at pH 12 and the biologically important one at pH 6.6.
This gives it amazing buffering ability and helps cells stay at a pH of 7.1 |
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What functional group is phosphatidic acid most reactive with? |
Very reactive with alchols and binds with them via ester bonds. |
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What molecules are derivied from cholesterol? |
Steroids; testosterone and estradiol ect. |
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What is the critical micelle concentration? |
The point at which fatty acids reach their solubility limit in water and begin forming a new micelle.
As new micelles form, the concentration of loose fatty acids is constant.
A higher CMC indicates greater water soluability.
Not a constant value, varries with salt concentration, ect. |
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What causes fatty acids to form either a micelle or a liposome? |
The greater the diffrence in head and tail volume the more likely it is for them to form micelles
The closer the head and tail volume are the more likely they will form liposomes. |
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What is a physiologicly imprortant Micelle? |
Cholesterol dirivetives found in bile salts, which form micelles with ingested fat. |
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What are aquaporins? |
Trans membrane proteins that let water move in and out of the cell more easily. |
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What is osmotic pressure? |
Using a u-tube, Pure water and a solution are allowed to diffuse across a semipermiable membrane. They start of even, but water moves to the solution side, causing it to rise above the pure water side.
By applying pressure to the side with greater volume they can be forced to equalize, the amount of pressure required to do this is the osmotic pressure. |
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What is facilitated diffusion? |
Proteins in the membrane selectively allow certian molecules through the membrane. This requires no energy! |
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How dose cholesterol effect membrane fluidity? |
Decreases it at high temps, and raises it in low temps. |
