MMT: Lipids I and II

Question 1

Define the term lipid in terms of their basic properties

Answer 1

molecules that are insoluble in aqueous solutions and soluble in nonpolar solvents

Question 2

State the major roles of biological lipids

Answer 2

storage form of energy (triacylglycerols), structural component of membranes, serve as vitamins and hormones, serve as cofactors

Question 3

List the five common types of lipids

Answer 3

1. fatty acids
2. acylglycerols
3. phosphoacylglycerols
4. shingolipids
5. steroids

Question 4

Describe the common features of fatty acids

Answer 4

1. hydrocarbon chains with a carboxylic acid group at one end (negative charge at physiological pH).
2. in animals, the carbon chains are unbranched.
3. double bonds are in cis configuration
4. double bonds are unconjugated, aka separated by methylene groups

Question 5

Explain the difference between saturated and unsaturated fatty acids

Answer 5

saturated: fully saturated with hydrogens; no double bonds. short chains (8C) are liquid at room temperature, while longer chains are solid at room temperature. most of the saturated chains are longer, so they’re usually solid at room temperature and increase rigidity.

unsaturated: not saturated with hydrogens, so double bonds are seen. the double bonds lower the melting point and allow for more fluidity

Question 6

describe the nomenclature sytems for unsaturated fatty acids

Answer 6

1. systematic nomenclature system: carbon #1 at the carboxyl. number of carbons: number of sites of unsaturation. anoic acid means no double bonds, enoic acid means one double bond, dienoic acid means two double bonds. ex: octadecadienoic acid (C18:2) means 18 carbons and 2 double bonds
2. deltaX system: systematic nomenclature with the addition of the location of the double bond. starting from c1 at the carboxyl, count until reaching the bond. formate is Cy:z deltaX, with y being number of carbons, z being number of double bonds, and x being the carbon number where the double bond begins. name all double bonds in the structure.
3. omega nomenclature: deltaX system with the addition of omega counting. counting from the terminal methyl group (omega carbon) to the first carbon in the double bond. format is Cy:z omegaW deltaX, with y being number of carbons, z being number of double bonds, x being the carbon number where the double bond begins counting from the carboxyl, and W being the carbon number where the double bond begins counting from the omega carbon. for omega, only count the first encountered bond if there’s more than one.

Question 7

describe the nomenclature system for saturated fatty acids

Answer 7

systematic nomenclature system: carbon #1 at the carboxyl, terminal methyl group is the omega carbon. number of carbons: number of sites of unsaturation. ex: Octanoic acid C8:0 has 8 carbons and no double bonds

Question 8

Distinguish between cis- and trans- double bonds in unsaturated fatty acids

Answer 8

cis bonds tend to occur more in nature. these bonds create a kink, while trans look like a traditional hydrocarbon chain. unsaturated fatty acids with cis configuration tend to be liquid at room temperature.

the trans unsaturated fatty acids are created by partial hydrogenation of cis fatty acids and tend to be used in the restaurant industry to increase shelf life; they’re solid at room temperature.

Question 9

List the four unsaturated fatty acid families and indicate which ones are essential

Answer 9

1. palmitoleic
2. oleic
3. linoleic (essential)
4. alpha-linoleic (essential)

Question 10

why are trans unsaturated fatty acids an issue?

Answer 10

since our bodies are euipped to deal with primarily cis unsaturated fatty acids, trans unsaturated fatty acids in large amounts obtained from food pose an issue as our body does not have a good way to break them down. as such, they accumulate in our system and lead to things like heart disease.

Question 11

State several major benefits of including long-chain omega-3 fatty acids in the diet.

Answer 11

preventing arythmia, atheroscleorisis, alzheimers. help with blood clotting and immune regulation.

Question 12

State the general outcomes of essential fatty acid deficiency

Answer 12

lowered immune system and lowered health in general!

Question 13

Describe the common features of acylglycerols and phosphoacylglycerols

Answer 13

both have a glycerol backbone and fatty acids attached, but acylglycerols have 3 fatty acids attached while phosphoacylglycerols have 2 fatty acids and one phosphate group

Question 14

List different types of phosphoacyglycerols

Answer 14

PS, PE, PC, PI, PA

connection: PC and PS are common outside membrane, PA, PI, PE inside!

Question 15

Describe the role of dipalmitoyl phosphatidylcholine in respiratory distress syndrome (RDS)

Answer 15

dipalmitoyl phosphatidylcholine is a major component of lung surfactant, which is required to help keep the lungs inflated by decreasing surface tension. premature babies don’t create dipalmitoyl phosphatidylcholine, reducing secretion of lung surfactant and leading to the potential collapse of the lungs

Question 16

name key signs of respiratory distress syndrome

Answer 16

1. retraction of the chest
2. nasal flaring
3. tachypnea (RR>60)
4. tachycardia (HR>160)
5. grunting
6. cyanosis

Question 17

how do we treat RDS

Answer 17

lung surfactant from cow lungs; their protein components are similar to ours so their surfactant works well

Question 18

Describe the common features of sphingolipids

Answer 18

they contain a sphingosine backbone made from palmitoyl CoA and serine, and a reactive hydroxyl and amino group at the polar end

Question 19

ceramide: structural and functional features

Answer 19

sphingosine (palmitoyl CoA and serine) with the addition of a fatty acyl CoA via amide linkage.

Question 20

sphingomyelin: structural and functional features

Answer 20

sphingosine backbone, fatty acid, and phosphocholine. component of myelin sheaths

Question 21

cerebroside: structural and functional features

Answer 21

a glycosphingolipid with sphingosine, fatty acid, and glucose or galactose. primarily found in the brain

Question 22

globoside: structural and functional features

Answer 22

a glycosphingolipid with sphingosine, fatty acid, and more than one sugar unit. important in the nervous system

Question 23

sulfatide: structural and functional features

Answer 23

a glycosphingolipid with sphingosine, fatty acid, and galactose linked to sulfate. important in the nervous system

Question 24

ganglioside: structural and functional features

Answer 24

a glycosphingolipid with sphingosine, fatty acid, and an oligosaccharide chain containing saliac acid (negative charge). important in the nervous system

Question 25

Describe the functional roles of sphingosine, S1P, ceramide and C1P

Answer 25

1. ceramide: makes other sphingolipids; can be activated and lead to signaling processes

Question 26

Distinguish between a ganglioside and a neutral (non-charged) glycosphingolipid

Answer 26

gangliosides have a negative charge due to sialic acid (NANA) residues. as a result, they can interact with hormone receptors and form ionic interactions on the surface of the plasma membrane.

Question 27

Define gangliosidoses

Answer 27

lysosomal storage diseases associated with defective enzymes that process gangliosides. this causes the accumulation of gangliosides and causes cell damage.

Question 28

Tay-Sachs disease: cause/enzyme involved and symptoms

Answer 28

a gangliosidosis condition in which GM2 accumulates due to deficient hexosaminidase. symptoms include mental delays, cherry red spots on retina, and psychomotor dysfunction.

Question 29

Describe the common features of steroid molecules

Answer 29

contain a four-ring structure called the steroid nucleus and are synthesized from acetyl-CoA. they stabilize cell membranes, are a component of bile salts, and are a precurser to steroid hormones

Question 30

Specify the functional roles and derivatives of cholesterol

Question 31

Contrast free and esterified cholesterol

Answer 31

esterified cholesterol occurs when cholesterol reacts with a fatty acyl chain, and the two are connected by an ester linkage. they’re extremely hydrophobic and are found in lipoprotein particles. free cholesterol has a hydrophilic portion, but the hydrophilic region is used to link the cholesterol to the fatty acyl, taking it out of commission.

Question 32

give the structure for palmitic acid

Answer 32

C16:0 hexadeconate

Question 33

give the structure for linoleic aid

Answer 33

C18:2 omega6 (delta 9,12- octadecadienoate)

Question 34

give the structure for a-linoleic acid

Answer 34

C18:3 omega3 (delta 9,12,15- octadecatrienoate)

Question 35

arachidonic acid is derived from ___ via…

Answer 35

linoleic acid by modifying the fatty acid chain closest to the carboxyl group, less than delta 9

Question 36

give the general structure of acylglycerols

Answer 36

glycerol backbone that can link 1-3 fatty acids via ester linkage. theyre water soluble and are a large storage form of energy (triacylglycerols)

Question 37

give the general structure of phosphoacylglycerols

Answer 37

contain a glycerol backbone, two fatty acids linked, and a phosphate group linked. they are a major component of our membranes, as they are amphipathic!