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Flashcards in Exam II Deck (17):
1

What are some characteristics of fatty acids?

-modify proteins via covalent bonding allowing them to target membranes
-can be stored as fuels in the form of triacylglycerols
-derivatives serve as hormones, signal molecules, and intracellular messengers

2

What are the two rules discussed in class about the nomenclature of fatty acids?

1. derived from the parent hydrocarbon
-no double bond, -anoic
-one double bond, -enoic
-two double bonds, -dienoic
-three double bonds, -trienoic
2. 18:0 represents a fatty acid with 18 Cs and no double bonds
18:2 represent a fatty acid with 18 Cs and two double bonds

3

How are carbon bonds numbered? Double bonds?

carbons:
-starting at carboxyl terminus
-carbon 2 (alpha) and 3(beta)
-methyl carbon at distal end is referred to as omega

Double bonds:
-position of double bond is denoted by (delta) followed by superscript
-counting from the distal end requires the omega to be number one and will be denoted as (omega)-3

4

What are some properties of fatty acids?

-contain an even number of carbons, between 14-24
+16 and 18 are most common fatty acids
-most unsaturated fatty acids contain cis double bonds
-fatty acids are ionized at physiological pH so it should be referred to as it's carboxylate form ex. palmitate -> palmitic acid
-unsaturated fatty acids have a lower melting than saturated fatty acids of the same length
-the melting points of saturated fatty acids increase with chain length

5

What are the essential fatty acids and non-essential? Name the number of Cs, double bonds, and common name.

Nonessential:
-palmitate, 16C, and 0 bonds
-stearate, 18Cs, 0 bonds

omega-6 essential:
-linoleate, 18Cs, 2 bonds
-arachidonate, 20Cs, 4 bonds

omega-3 essential:
-linolenate, 18Cs, 3 bonds

6

How is an archaea able to withstand such high temperatures?

-the membrane lipid contains an ether linkage which is more resistant to hydrolysis
-the branched and saturated hydrocarbons are more resistant to oxidation

7

What are the three major membrane lipids?

-phospholipids
-glycolipids
-cholesterol

8

What are the 4 components of a phospholipid?

-fatty acid- hydrophobic barrier
-backbone to which fatty acids are attached: glycerol (3C alcohol; phosphoglycerides) or spingosine (complex alcohol; sphingomyelin)
-phosphate
-alcohol attached to the phosphate

9

What is the key intermediate in the biosynthesis of phosphoglycerides?

phosphatidate -> small amount present in membranes

10

What are the phosphoglycerides derived from phosphatidate and what are their purpose?

-phosphatidylserine: memory and cognition
-phosphotidylcholine: major constituent of cell membrane and pulmonary surfactant
-phosphatidylethanolamine: 25% of phospholipids, found in nervous tissue such as white matter of the brain
-phosphatidylinositol: important signaling and other functional activities in eukaryotic cells
-diphosphatidylglycerol: important component of inner mitochondrial membrane

11

What is a sphingosine?

an amino alcohol that contains a long, unsaturated hydrocarbon chain

12

What is sphingomyelin?

-the phospholipid with the sphingosine as the backbone
-amino group of the spingosine backbone linked to a fatty acid via an amide bond
-found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons

13

What are glycolipids?

-sugar-containing lipids
-derived from sphnigosine
-differ from spingomyelin is the identity of the unit that is linked to the primary hydroxyl group of the sphingosine backbone
-oriented with the sugar residues always on the extracellular side of the membrane

14

What is the simplest glycolipid and what are some of it's characteristics?

-cerebroside!
-contains a single sugar residue (glucose or galactose)
-cerebroside is the common name for the group of glycosphingolipids called monoglylceramides which is an important component in animal muscle and nerve cell membranes

15

What are some characteristics of cholesterol?

-a steroid (most common), present in eukaryotes but not most prokaryotes
-built from 4 fused hydrocarbon rings
-classified as a sterol
-major component of eukaryotic plasma membrane
+absent from the intracellular membranes
+absent in prokaryotes
+oriented parallel to the fatty acid chains of the phospholipids, and the hydroxyl group interacts with the phospholipid head
-metabolic precursor of steroid hormones

16

What is a lipid?

-water insoluble biomolecules that are highly soluble in organic solvents
-make up the cell membrane
-composed of fatty acids, causing the lipid to be hydrophobic

17

A researcher mutated a critical domain of the Na+/K+ ATPase gene. When expressed in cells, the mutated protein was unable to form the E-P intermediate in the reaction cycle of the enzyme. Which of the following aa was most likely

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