Deck 5: Lipids

Question 1

Margarine usually is made by a process called _____, in which hydrogen atoms are added to carbon-carbon double bonds in the polyunsaturated fatty acids found in vegetable oils.

A) saturation
B) esterification
C) isomerisation
D) hydrogenation

Answer 1

Margarine is primarily used as a substitute for butter and produced from vegetable oils or fats. Conversion to margarine increases its shelf life and reduces the incidence of rancidity caused by oxidation.
Margarine is produced from vegetable oils which have unsaturated carbon atoms, that is carbon atoms bonded to each other by double bonds. Margarine is saturated compound having carbon-carbon single bonds. Though the process results in a saturated product, it is not referred to as saturation, but by another name that points to the changes that are responsible for bringing about the saturation.
Esterification is the process of conversion of a carboxylic acid and alcohol to an ester. Margarine is produced from vegetable oils or fats and not carboxylic acids, and margarine is not an ester but a type of fat.
Isomerization is the process by which a compound having the same atomic composition is produced with a different orientation or structure. Margarine is produced from vegetable oils or fats that have less hydrogen atoms compared to margarine, which means its atomic composition changes after the process.
Thus, the options a, b, and c would be incorrect.
Unsaturated organic compounds having double bonds are converted to saturated compounds by various means. One of the ways is to add hydrogen atom to one of the carbons forming the double bond. The process is referred to as hydrogenation. Vegetable oils or fats are converted to margarine by passing hydrogen under pressure. Margarine is made by the process of hydrogenation.
Thus, the correct option would be the option
.

Question 2

Describe the chemical structures of saturated and polyunsaturated fatty acids and their different effects in both food and the human body.

Answer 2

Fatty acids are organic molecules comprising of carbon and hydrogen atoms. They have the carboxylic group (-COOH) in their structure which classifies them chemically as carboxylic acids. Fatty acids can broadly be classified, based on their structure, as saturated and unsaturated fatty acids. The unsaturated fatty acids can be further classified into monounsaturated and polyunsaturated fatty acids.
Saturated fatty acids comprise of carbon atoms bound by carbon-carbon single bonds. They have a straight and linear structure, and thus are densely packed. At room temperature therefore there can exist as solids. Triglycerides are an example of saturated fatty acids commonly found in food as well as the body.
The polyunsaturated fatty acids (PUFA) have carbon atoms bound by carbon-carbon double bonds. When the carbon atoms are oriented in opposite directions, the polyunsaturated fatty acids are referred to as trans fatty acids. They exist mostly as liquids at room temperature such as corn, sunflower, safflower, and soybean oils. Omega-3 (linolenic acid), omega-6 (linoleic acid), and omega-9 are some of the important polyunsaturated fatty acids. They have the carbon-carbon double bonds are the third, sixth, and ninth carbon atoms, respectively. While the latter is made in the body, the former two are not and hence referred to as essential fatty acids. Nuts, seeds, fatty fish, and canola oil are important sources of omega-3 fatty acids. beef, poultry safflower oil, and corn oil are rich sources of omega-6 fatty acids.
Fatty acids play the important role of providing energy to the body when glucose is not available. They form the building blocks of hormone-like substances such as prostaglandins and other hormones. When energy from fatty acids is not required, the surplus fatty acids are stored in the form of triglycerides. Triglycerides form the visceral and body fat and help in transportation of the fat-soluble vitamins.
While saturated fatty acids play an important role in the normal physiology of the body, their consumption at higher levels increases the low-density cholesterol in the blood, leading to fat deposition in the vessels, narrowing the channel and reducing the capacity of the blood to deliver oxygen. Saturated fatty acids must be consumed in restricted amounts.
Like the saturated fatty acids, the trans fatty acids too can have a harmful effect on the body due to their tendency to increase the low-density cholesterol levels. Among the unsaturated fatty acids, the essential fatty acids, namely, omega-3 and omega-6 are beneficial to the body. Omega-3 has anticoagulative properties and tend to increase the levels of prostacyclin which discourages clotting of blood. They tend to reduce the blood pressure and inflammatory responses in the body. The omega-6 fatty acids tend to increase the clotting of blood.

Question 3

Essential fatty acids that cause a decrease in blood clotting are

A) omega-3.
B) omega-6.
C) omega-9.
D) prostacyclins.

Answer 3

When the body is deficient in carbohydrates, fatty acids provide energy by the process of gluconeogenesis. The body, however, cannot produce all the fatty acids required by it. Some of the fatty acids need to be consumed from dietary sources. These fatty acids are referred to as essential fatty acids. The ones that can be produced in the body are referred to as non-essential fatty acids.
Omega 6 is an essential fatty acid that helps in the production of factors that cause clotting.
Omega-9 is a fatty acid that can be produced by the body and is not an essential fatty acid. It helps in increasing the high-density cholesterol and reducing the low-density cholesterol but has not role in the clotting mechanism. Prostacyclin helps in preventing aggregation of platelets and is produced by endothelial and vascular muscle cells. It prevents clotting of blood, but it is a hormone-like substance and not a fatty acid.
Thus, options b, c, and d are incorrect.
Studies conducted in surgical experiments have shown the influence of omega-3 in releasing prostacyclin from the vascular tissues, resulting in less bleeding during surgery. Omega 3 is an essential fatty acid that facilitates the secretion of hormone-like substances such as prostacyclin that tend to reduce blood-clotting by inhibiting platelet activation.
Thus, the correct option would be the option
.

Question 4

Relate the need for omega-3 fatty acids in the diet to the recommendation to consume fatty fish at least twice a week.

Question 5

Cholesterol is

A) a dietary essential; the human body cannot synthesize it.
B) found in foods of plant origin.
C) an important part of human cell membranes and necessary to make some hormones.
D) All of the above.

Question 6

Describe the structures, origins, and roles of the four major blood lipoproteins.

Question 7

Which of the following groups of foods would be important sources of saturated fatty acids

A) olive oil, peanut oil, canola oil
B) palm oil, palm kernel oil, coconut oil
C) safflower oil, corn oil, soybean oil
D) All of the above.

Question 8

What are the recommendations from various health care organizations regarding fat intake What does this mean in terms of food choices

Question 9

Lipoproteins are important for

A) transport of fats in the blood and lymphatic system.
B) synthesis of triglycerides.
C) synthesis of adipose tissue.
D) enzyme production.

Question 10

What are two important attributes of fat in food How are these different from the general functions of lipids in the human body

Question 11

Which of the following foods is the best source of omega-3 fatty acids

A) fatty fish
B) peanut butter and jelly
C) lard and shortenings
D) beef and other red meats

Question 12

Describe the significance of and possible uses for reduced-fat foods.

Question 13

Immediately after a meal, newly digested and absorbed dietary fats appear in the lymph and then the blood as part of which of the following

A) LDL
B) HDL
C) chylomicrons
D) cholesterol

Question 14

Does the total cholesterol concentration in the bloodstream tell the whole story with respect to cardiovascular disease risk

Question 15

High blood concentrations of _____ decrease the risk for cardiovascular disease.

A) low-density lipoproteins
B) chylomicrons
C) high-density lipoproteins
D) cholesterol

Question 16

List the four main risk factors for the development of cardiovascular disease.

Question 17

Phospholipids such as lecithin are used extensively in food preparation because they

A) provide the agreeable feel of fat melting on the tongue.
B) are excellent emulsifiers.
C) provide important textural features.
D) impart delicate flavors.

Question 18

What three lifestyle factors decrease the risk of cardiovascular disease development

Question 19

The main form of lipid found in the food we eat is

A) cholesterol.
B) phospholipids.
C) triglycerides.
D) plant sterols.

Question 20

When are medications most needed in cardiovascular disease therapy, and how in general do the various classes of medications operate to reduce risk

Question 21

What is the common property that all lipid compounds share

Question 22

What are the four possible structural forms of lipid

Question 23

In what ways do fatty acids differ from one another

Question 24

What is the difference between a saturated and an unsaturated fatty acid, and between an omega-3 and an omega-6 fatty acid

Question 25

Which fatty acids are essential

Question 26

How do triglycerides differ from phospholipids

Question 27

What are the main functions of cholesterol in the body

Question 28

Which foods are the most fat-dense ( 60% total calories as fat)

Question 29

Where is cholesterol found in the food supply

Question 30

Which types of fat are used as emulsifiers, and what is their function in food

Question 31

What are some strategies used to produce reduced-fat foods

Question 32

How do fats become rancid, and how can this be prevented

Question 33

What happens to unsaturated fats during the process of hydrogenation

Question 34

What regulations are in place to educate and protect the public from trans fats in foods

Question 35

What enzyme is responsible for digestion of triglycerides

Question 36

What are the end products of fat digestion

Question 37

What are the differences between the absorption of long- versus short-chain fatty acids

Question 38

How do lipids move through the bloodstream

Question 39

How are dietary fats packaged in the small intestine and transported

Question 40

Where are VLDLs made and what do they contain

Question 41

Where do the LDLs originate and what is their destination

Question 42

Why are HDLs considered "good" cholesterol

Question 43

What are the functions of triglycerides in the body

Question 44

Where are phospholipids found in the body

Question 45

What are some compounds that are made from cholesterol in the body

Question 46

How does the percent of calories as fat in the North American diet compare to recommendations

Question 47

What is the limit for cholesterol intake

Question 48

What are the characteristics of the Mediterranean diet