Lipids

Question 1

What are lipids?

Answer 1

Lipids are a diverse group of carbon compounds that share the property of being insoluble in water

Question 2

What are the three main types of lipids?

Answer 2

1. Triglycerides
2. Phospholipids
3. Steroids

Question 3

What are triglycerides made up of?

Answer 3

Triglycerides are made from three fatty acids and one glycerol by condensation reactions.

Question 4

What are the 2 main functions of triglycerides?

Answer 4

1. Long-term energy stores (as fats in animals and oils in plants)
2. Used as heat insulators (blubber of Arctic animals)

Question 5

What are fatty acids?

Answer 5

Fatty acids are long hydrocarbon chains that are found in certain types of lipids

Question 6

What are the two types of fatty acids?

Answer 6

1. Saturated fatty acids
   
   • All of the carbon atoms in the chain are connected
     by single covalent bonds so the number of
     hydrogen atoms are maximized
   • Linear in structure & originate from animal sources
2. Unsaturated fatty acids
   
   • Unsaturated fatty acids contain one or more double
     bonds between carbon atoms in the chain, so the
     number of hydrogen atoms are not maximized
   • Bent in structure & originate from plant sources

Question 7

What are the two types of unsaturated fatty acids

Answer 7

1. Cis unsaturated fatty acids
   
   • Hydrogen atoms are bonded to carbon atoms on
     the same side of a double bond
   • Loosely packed and have low melting points
2. Trans unsaturated fatty acids
   
   • Hydrogen atoms are bonded to carbon atoms on
     opposite sides of a double bond
   • Closely packed and have high melting points
   • Generally do not occur in nature and are typically
     produced by an industrial process called
     hydrogenation

Question 8

What are the health risks of fats?

Answer 8

• Saturated fats and transfats have negative health effects, while unsaturated (cis) fats have positive health effects
• There is a positive correlation between amounts of transfats consumed and rates of coronary heart disease; higher amounts of transfats have been recorded in patients’ arteries
• There is a positive correlation between saturated fatty acid intake and rates of CHD in many research programs, but not all populations fit this correlation

Question 9

Carbohydrates vs Lipids

Answer 9

Advantages of lipids:

• Stores twice as much ATP per gram as carbohydrates
• Does not associate with water, making it even lighter in the body compared to carbohydrates (more efficient)
• Better heat insulators
• Can act as a shock absorber

Disadvantages of lipids:

• carbohydrates are easier to transport
• carbohydrates are easier to digest and utilize

Question 10

What is body mass index (BMI)?

Answer 10

BMI = mass in kilograms / (height in metres)^2

• below 18.5: underweight
• 18.5 - 24.9: normal weight
• 25.0 - 29.9: overweight
• 30.0 or more: obese