Lipids and triglycerides

Question 1

What are uses of lipids?

Answer 1

Respiration, energy storage, membranes, thermal insulation, electrical insulation and protection

Question 2

How are lipids used in respiration?

Answer 2

They release ATP

Question 3

How are lipids used for energy storage?

Answer 3

They form adipose tissue in animals and lipid droplets in plants

Question 4

How are lipids used in membranes?

Answer 4

There are phospholipids

Question 5

How are lipids used as thermal insulation?

Answer 5

They form a layer under the skin in mammals

Question 6

How are lipids used as electrical insulation?

Answer 6

They exist on some nerve cells (myelin sheath)

Question 7

How are lipids used as protection?

Answer 7

They protect organs, plant leaves and stems (waxy cuticle)

Question 8

What are lipids?

Answer 8

Large, complex macromolecules categorised into triglycerides (dietary fats and oils used to make other things), phospholipids (cell membranes) and sterols (hormones and waxes, including cholesterol)

Question 9

What elements are lipids made of?

Answer 9

Carbon, hydrogen and oxygen

Question 10

Are lipids soluble?

Answer 10

They don’t dissolve in water as they are non-polar but will dissolve in organic solvents, such as alcohols

Question 11

What are triglycerides?

Answer 11

An energy storage that makes membrane lipids (phospholipids) and are made of 1 glycerol and 3 fatty acids

Question 12

What is glycerol?

Answer 12

An 3 carbon alcohol that fatty acids join onto in a triglyceride and always remains the same 3C group

Question 13

What are fatty acids?

Answer 13

Carboxylic acids (consists of -COOH groups) with a hydrocarbon chain attached to

Question 14

What do both fatty acids and glycerol contain?

Answer 14

-OH groups

Question 15

What is a hydrocarbon chain?

Answer 15

A chain of carbon atoms bonded together with a variable number of hydrogen atoms bonded to either side of the carbons

Question 16

What is an ester bond?

Answer 16

A bond formed when an organic acid joins to an alcohol by a condensing reaction and the -OH groups interact

Question 17

Where does an ester bond form in a triglyceride?

Answer 17

Between the -OH group in the carboxyl group of the fatty acids and the -OH group on the glycerol, forming 3 water molecules which are removed

Question 18

How can an ester bond be broken?

Answer 18

By lipase by hydrolysis

Question 19

What is the difference between saturated and unsaturated hydrocarbons?

Answer 19

Saturated hydrocarbons have no carbon-to-carbon double bond whereas unsaturated hydrocarbons contain at least 1 carbon-to-carbon double bond

Question 20

What are variations within fatty acids?

Answer 20

They can be essential or non-essential, saturated or unsaturated, the number of carbon atoms, the number of double bonds and some are kinkier than others as each double bond forms a kink in the fatty acid tail

Question 21

What are similarities in fatty acids?

Answer 21

They all have -COOH at one end which is what attaches to the glycerol via the -OH, they all have -CH₃ (methyl groups) at the other end and they all have chains of carbons attached to each other with hydrogen atoms attached to each carbon

Question 22

What are oils?

Answer 22

Triglycerides containing unsaturated fatty acids as they cannot pack together tightly so they are liquid at room temperature

Question 23

Where are oils found?

Answer 23

In plants and are generally healthier to eat

Question 24

Why are triglycerides insoluble in water?

Answer 24

There is a methyl group at one end of the fatty acid tail which makes it hydrophobic

Question 25

Why are triglycerides non-polar?

Answer 25

Charges are distributed evenly around a triglycerides so hydrogen bonds cannot readily form its water

Question 26

What is a benefit of triglycerides being insoluble?

Answer 26

They can be stored in a a compact way and don’t effect the cell’s water potential

Question 27

How do triglycerides work in respiration?

Answer 27

They are also an energy store molecule and are respired to form carbon dioxide and release energy in the form of ATP which produces twice the amount of energy than a carbohydrate. Much more water is also produced

Question 28

What is metabolic water?

Answer 28

Triglyceride hydrolysis produces water which is essential for the survival of desert animals

Question 29

What are functions of triglycerides?

Answer 29

Provide protection around internal organs, provide a layer of insulation under the skin known as blubber and be stored as adipose tissue in fat cells where energy input in greater than energy output but is bad for the heart