Lipids topic 2.3

Question 1

Functions of Lipids

Answer 1

Lipids are a class of non-polar organic molecules
* Include triglyceride (adipose tissue), phospholipid (bilayer),
cholesterol (animal cell membrane), steroids (hormones)

Question 2

Lipids may serve a variety of cellular functions, including:

Answer 2

• Storage of energy (triglycerides)
• Hormonal roles (steroids)
• Insulation (thermal)
• Protection of organs
• Structural roles (cholesterol)

Question 3

Triglycerides

Answer 3

Triglycerides are lipids used for long-term energy storage

They are composed of a glycerol molecule covalently linked
to three fatty acid chains (via condensation reactions)

Question 4

Fatty Acids

Answer 4

Fatty acids are long hydrocarbon chains found in certain lipids
* Principally found in triglycerides and phospholipids

Question 5

Saturated Fatty Acids

Answer 5

• Possess no double bonds in the hydrocarbon chain
• Are generally solid at room temperatures (e.g. animal fat)

Question 6

Unsaturated Fatty Acids

Answer 6

• Possess double bonds (mono = one ; poly = many)
• Are generally liquid at room temperature (e.g. plant oils)

Question 7

Lipid Health Risks

Answer 7

Fats and cholesterol cannot dissolve in the blood and so are
packaged with proteins (as lipoproteins) for transport

• Low density lipoproteins (LDLs) transport cholesterol
  from the liver to the rest of the body (bad for health)
• High density lipoproteins (HDLs) scavenge excess
  cholesterol and return it to the liver for disposal (good)