Module 1 - Lipids

Question 1

What are lipids

Answer 1

Lipids are diverse group of compounds that are

insoluble in water but soluble in organic solvents

Question 2

What are 3 things that lipids are used for?

Answer 2

The storage of energy, structural components of hormones and as signalling molecules.

Question 3

What is triglyceride?

Answer 3

A type of lipid that contains one glycerol molecule and 3 fatty acid molecules formed through ester bonds.

Question 4

What do lipids consist of

Answer 4

Lipids contain hydrogen, carbon and oxygen

Question 5

What are 3 types of lipids that are formed?

Answer 5

Saturated = One consists of single covalent bonds
Monounsaturated = One double covalent bond
Polyunsaturated = More than one double covalent bond

Question 6

What property does double bonds give lipids.

Answer 6

More than one double bond allows polyunsaturated lipids to bend which allows them to remain a liquid at room temperature.

Question 7

What property do hydrogen and carbon atoms provide lipids?

Answer 7

Lipids contains lots of hydrogen and carbon meaning that a great deal of energy could be released.

Question 8

What type of reaction occurs between glycerol and the 3 fatty acid molecules? Why?

Answer 8

A condensation reaction because 3 water molecules are produced

Question 9

Give 2 properties of triglycerides.

Answer 9

They are non polar (hydrophobic) meaning that they do not dissolve in water, Large amount of carbon and hydrogen atoms meaning a great deal of energy can be released.

Question 10

Where are lipids stored?

Answer 10

Adipose tissue

Question 11

What are 2 important roles of adipose tissue?

Answer 11

Heat insulation: Within mammals, adipose tissue is under the skin to help prevent heat loss.
Protection: it is also around delicate organs in order to act as a cushion against impacts.

Question 12

What cells are contained within adipose tissue?

Answer 12

Fat cells = adiphocyte.

Question 13

What are phospholipids?

Answer 13

Phospholipids are major components of cell membranes

Question 14

What is the structure of phospholipids?

Answer 14

Phospholipids contain a phosphate molecule and 2 fatty acid molecules.

Question 15

What property does the phosphate group have in the structure of phospholipids?

Answer 15

Phosphate molecule is hydrophilic attracts water because it is the charged end of the molecule.

Question 16

What properties do the fatty acid molecules have in phospholipids?

Answer 16

Non-polar long chain of hydrocarbons and hydrophobic (repels water).

Question 17

What is the name of the test used to test for lipids?

Answer 17

An emulsion test

Question 18

Describe the emulsion test.

Why does the emulsion form?

Answer 18

Get a clean test tube including a sample. Then add a sample of ethanol and mix well. Add some water and mix thoroughly. If a white cloudy emulsion appears then there a lipid is present. This emulsion forms because lipids are hydrophobic meaning they repel water and so the lipid globules will separate from the solution forming an emulsion.

Question 19

How do phospholipids contribute to cell membrane structure?

Answer 19

Phospholipids orient their heads towards the polar molecules and tails in the interior of the cell membrane, thus forming a bilayer.

Question 20

What are three functions that lipids serve in plants and/or animals?

Answer 20

Lipids serve in the storage of energy, as a structural component of hormones and, as a signalling molecule.

Question 21

What is a phospholipids purpose in a cell membrane?

Answer 21

Forms a lipid bilayer. The hydrophobic tails repels water so in faces inwards and the hydrophilic head attracts water so faces outwards.

Question 22

Explain two ways in which fatty acids are important in the formation of new cells

Answer 22

They can be used in respiration to provide energy for the formation of new cells
They can also be used to make phospholipids in membranes.