Chp 10 - Lipids

Question 1

What are the 5 categories lipids can be divided into?

Answer 1

A) Energy-storage lipids(triacylglycerols)
B) Membrane lipids (phospholipids, sphingoglycolipids, & cholesterol)
C) Emulsification lipids (bile acids)
D) Chemical messenger lipids (steroid hormones and eicosanoids)
E) Protective-coating lipids (biological waxes

Question 2

Describe the two general types of fatty acids.

Answer 2

Saturated fatty acids only have single bonds.
Unsaturated fatty acids have one or more double bond. Monosaturated fatty acid - Only 1 double bond between 2 carbons. Polysaturated - more than one double bond

Question 3

Describe the structure’s impact on water solubility and melting points of fatty acids.

Answer 3

The longer the carbon chain the lower its solubility in water.
Fatty acid melting points depend on both the length of the carbon chain and the number of cis C=C present. Each cis C=C creates a “kink” that prevents tight packing and decreases melting point.

Question 4

Is the hydrocarbon chain and carboxylic acids hydrophobic or hydrophilic? Why?

Answer 4

Hydrocarbon chains are hydrophobic.
Carboxylic acids are hydrophilic.
All fatty acids have only one carboxylic acid, the size of the hydrocarbon portion dictates solubility. Unsaturated fatty acids (C=C) have minimal impact on water solubility.

Question 5

Give one example of energy-storage lipids.

Answer 5

Triacylglycerols

Question 6

Give one example of membrane lipids.

Answer 6

Sphingoglycolipids

Question 7

Give one example of Emulsification lipids.

Answer 7

Cholic acid

Question 8

Give one example of Chemical messenger lipids.

Answer 8

Testosterone

Question 9

Give one example of Protective-coating lipids.

Answer 9

A biological wax

Question 10

What are simple and mixed triacylglycerols?

Answer 10

Simple triacylglycerols contain three identical fatty acyl groups on a glycerol (R = R’ = R’’).
Mixed triacylglycerols contain 2-3 different types of fatty acyl groups on a glycerol.

Question 11

What are oils and fats?

Answer 11

A fat is a triacylglycerol mixture that is a solid or semi-solid at room temperature, while an oil is a triacylglycerol mixture that is a liquid at rt.

Question 12

Give two examples of good fats and bad fats.

Answer 12

Good Fats: Monounsaturated fats (ex. olive oil) and omega-3 fatty acids
Bad Fats: Saturated fats (ex. butter) and trans-unsaturated fats

Question 13

What are of the two most important essential fatty acids and summarize their two important functions?

Answer 13

Linoleic acid (18:2) - essential for proper membrane structure and is a precursor for omega-6 fatty acids like arachidonic acid.
Linolenic acid (18:3) - crucial for synthesizing omega-3 fatty acids, such as EPA and DHA. It also supports cardiovascular and brain health.

Question 14

What is Saponification?
When is saponification possible?

Answer 14

The hydrolysis of a lipid, triacylglycerol, in a basic solution, producing glycerol and fatty acid salts (soaps).
Possible in molecules that contain the ester, amide, and glycosidic linkages (bonds).

Question 15

Give a reaction example of a saponification.

Answer 15

Triacylglycerol + NaOH → Glycerol + Soap (sodium salt of fatty acid).

Question 16

What is hydrogenation?

Answer 16

Converting unsaturated fatty acyl groups to saturated fatty acyl groups. Involves the addition of hydrogen to unsaturated fatty acids, converting double bonds to single bonds, which can turn oils into semi-solids.

Question 17

Give a reaction example of hydrogenation.

Answer 17

Vegetable oil (unsaturated) + H₂ → Margarine (saturated fat).

Question 18

What is Oxidation?

Answer 18

When the double bonds of unsaturated lipids are broken down into smaller compounds when exposed to air; usually compounds like aldehydes and carboxylic acids.

Question 19

Give an example of an oxidation reaction.

Answer 19

Oxidation of linoleic acid (18:2) leading to shorter aldehydes or carboxylic acids.

Question 20

State a triacylglycerol and a glycerophospholipid function.

Answer 20

Triacylglycerols serve as energy storage molecules while glycerophospholipid function as components of cell membranes.

Question 21

Give two different types of hormonal lipids and where they are derived from.

Answer 21

Steroid Hormones (derived from cholesterol) and Eicosanoids (derived from arachidonic acid).

Question 22

Give the functions of Eicosanoids.

Answer 22

Prostaglandins: Involved in inflammatory responses, regulation of blood flow, and induction of fever
Leukotrienes: Play a role in inflammatory and allergic responses, like asthma

Question 23

Give the functions of Steroid Hormones.

Answer 23

Sex Hormones - Regulate reproductive functions and the development of secondary sex characteristics
Adrenocorticoid Hormones - Produced in the adrenal glands, these control glucose metabolism, reduce inflammation, and help balance electrolytes

Question 24

Give 2 examples of sex hormones. And an example of Adrenocorticoid Hormones.

Answer 24

Testosterone and estrogen; cortisol

Question 25

The chemical structure of waxes are generally very _____.

Answer 25

long

Question 26

Are all polyunsaturated fats good fats or bad fats?

Answer 26

Neither. Certain polyunsaturated fats and “bad” fats and some are “good” fats

Question 27

A glycerophospholipid chain replaced by phosphate makes it more ________.

Answer 27

polar

Question 28

True or false? Triacylglycerols only serve as energy storage molecules.

Answer 28

False. Triacylglycerols serve as energy storage molecules. Not only.

Question 29

What makes a glycerophospholipid chain more polar?

Answer 29

When it is replaced by phosphate.

Question 30

Which is polar and which is non polar between triacylglycerols and glycerophospholipids?

Answer 30

Triacylglycerols: non-polar
Glycerophospholipids: polar

Question 31

What is a glycerophospholipid?

Answer 31

A lipid that contains two fatty acids & a phosphate group esterified (linked) to a glycerol molecule & an alcohol esterified (linked) to the phosphate group

Question 32

How many ester linkages does glycerophospholipids and triacylglycerols have?

Answer 32

4; 2

Question 33

Which 3 AAs are usually the alcohol attached to the phosphate group in a glycophospholipid?

Answer 33

1. Choline (phosphatidylcholines)
2. Ethanolamine (phosphatidylethanolamines)
3. Serine (phosphatidylserines)

Question 34

List all the saturated FAs and their structural notations.

Answer 34

Lauric acid (12:0), myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), arachidic acid (20:0)

Question 35

List all the monounsaturated FAs and their structural notations.

Answer 35

Palmitoleic acid (16:1) w-7, oleic acid (18:1) w-9

Question 36

List all the polyunsaturated FAs and their structural notations.

Answer 36

Linoleic acid (18:2) w-6, linoleic acid (18:3) w-3, arachidonic acid (20:4) w-6, EPA/epicosapentaenoic acid (20:5) w-3, DHA/docosahexanenoic acid (22:6) w-6