lipids

Question 1

What is the origin of the term “aliphatic”?

Answer 1

It comes from the Greek word aleiphar (fat), referring to open-chain hydrocarbons made up

Question 2

What is the origin of the word “lipid”?

Answer 2

It comes from the Greek word lipos, meaning oil or fat, and refers to organic compounds that are insoluble in water.

Question 3

What is the structure of a fatty acid?

Answer 3

Fatty acids are long chains of carbon atoms with hydrogen atoms attached, and they can be classified as short-chain (water-soluble) or long-chain (fatty acids). The longest fatty acid is 28 carbons long.

Question 3

What are lipids and what are their functions?

Answer 3

Lipids are organic compounds that are hydrophobic (insoluble in water). They function as energy-storage molecules, chemical messengers, and components of biological membranes.

Question 4

What is the structure of triacylglycerol (TAG)?

Answer 4

TAG consists of a glycerol backbone attached to three fatty acids via ester bonds. The fatty acids are known as fatty acyl groups.

Question 5

What are the main types of lipids?

Answer 5

Lipids are classified into simple lipids (e.g., oils and fats made up of triacylglycerols), compound lipids (amphiphilic molecules found in membranes), and derived lipids (e.g., fat-soluble vitamins and carotenoids).

Question 6

What is the difference between simple and mixed TAG molecules?

Answer 6

Simple TAG molecules have all three fatty acids identical, while mixed TAG molecules have more than one type of fatty acid.

Question 7

How do fats and oils impact food processing?

Answer 7

Fats and oils allow for high-temperature cooking (e.g., frying), create layers in dough for puffing, and provide shortening effects in baking.

Question 8

What are the nutritional benefits of fats and oils?

Answer 8

Fats and oils provide calories, deliver essential fatty acids, and help with the absorption of lipid-soluble bioactive compounds such as carotenoids.

Question 9

How do fats enhance the bioavailability of carotenoids?

Answer 9

Consuming fats with plant material increases the absorption of lipid-soluble bioactive compounds like carotenoids into the body.

Question 10

What are some examples of fat-soluble pigments in food?

Answer 10

Examples include lycopene (tomatoes), lutein/zeaxanthin (maize), and astaxanthin (prawns).

Question 11

What are fat-soluble vitamins, and what is their role in the body?

Answer 11

Fat-soluble vitamins (e.g., Vitamin A from β-carotene) are obtained from fats and are essential for various physiological functions, such as vision and immune health.

Question 12

What are the main structural components of a fatty acid?

Answer 12

A hydrocarbon chain (alkyl chain or R group), a carboxylic acid group, and a methyl group.

Question 13

How are fatty acids classified based on saturati

Answer 13

Saturated: No double bonds.
Unsaturated: One or more double bonds (mono- or polyunsaturated).

Question 14

What enzymes catalyze the hydrolysis of ester bonds in TAG molecules?

Answer 14

Lipase enzymes.

Question 15

What numbering system do nutritionists use to number the position of double bonds in fatty acids?

Answer 15

The omega numbering system, where carbon atoms are counted from the methyl end.

Question 16

What happens to unsaturated fatty acids after they enter the body?

Answer 16

hey can be converted into fatty acids with more double bonds and longer chains, with alterations occurring on the carboxylic side.

Question 17

What remains intact during the conversion of unsaturated fatty acids in the body?

Answer 17

The omega numbering system remains intact.

Question 18

What are cis and trans isomers in fatty acids, and how do they affect shape?

Answer 18

Cis (Z): Methyl groups on the same side, causing a bend (kink).
Trans (E): Methyl groups on opposite sides, creating a straight configuration.

Question 19

What is the model molecule used to represent a segment of a fatty acid chain in the explanation?

Answer 19

Butane (C4H10).

Question 20

What happens in the eclipsed conformation of a fatty acid chain?

Answer 20

Bulky groups are close together, creating intramolecular tension.

Question 21

What is the most stable conformation for fatty acids, and why?

Answer 21

The anti-conformation is the most stable, as it is the lowest energy conformation where bulky groups are as far apart as possible.

Question 22

How does heating affect the conformation of a fatty acid chain?

Answer 22

Heating allows the molecule to adopt less favorable, non-linear, and buckled conformations.