Lipids

Question 1

What are the two main groups of lipids?

Answer 1

Triglycerides and phospholipids

These groups have different structures and properties.

Question 2

How are triglycerides formed?

Answer 2

By the condensation of one molecule of glycerol and three molecules of fatty acid

This process involves the formation of ester bonds.

Question 3

What type of bond is formed between glycerol and a fatty acid?

Answer 3

Ester bond

This bond is a result of a condensation reaction.

Question 4

What distinguishes saturated fatty acids from unsaturated fatty acids?

Answer 4

Saturated fatty acids have no double bonds in their hydrocarbon chain, while unsaturated fatty acids do

This difference affects their physical properties.

Question 5

In phospholipids, what replaces one of the fatty acids from a triglyceride?

Answer 5

A phosphate-containing group

This substitution is key to the structure of cell membranes.

Question 6

What is the emulsion test used for?

Answer 6

To test for the presence of lipids

It is a common laboratory test for lipids.

Question 7

What are the functions of triglycerides?

Answer 7

Storage molecules in food

They serve primarily as energy reserves.

Question 8

What role do phospholipids play in cells?

Answer 8

They help form the cell membrane

This is crucial for maintaining cell integrity.

Question 9

How do lipids conduct heat?

Answer 9

They conduct heat slowly

This property makes them good thermal and electrical insulators.

Question 10

What is a characteristic of fats compared to oils?

Answer 10

Fats are solid and saturated, while oils are liquid and unsaturated

Fats are typically found in animals, oils in plants.

Question 11

Lipids are described as __________ and __________.

Answer 11

Insoluble and hydrophobic

These properties make them resistant to mixing with water.

Question 12

Where are lipids stored around the body for protection?

Answer 12

Around delicate organs, such as the kidneys

This storage provides cushioning and protection.

Question 13

What are triglycerides made of?

Answer 13

One molecule of glycerol and three fatty acids joined by ester bonds

Question 14

Are triglycerides considered polymers?

Answer 14

No, they are not made of the same or similar monomers

Question 15

What is the carbon range typically found in fatty acids?

Answer 15

12-20 carbon atoms

Question 16

What type of reaction forms lipids?

Answer 16

Condensation reactions

Question 17

What are the bonds formed between glycerol and fatty acids called?

Answer 17

Ester bonds

Question 18

What is a point mutation?

Answer 18

A change to a DNA sequence of a gene

Question 19

What can a point mutation result in?

Answer 19

A change in the primary structure of a protein

Question 20

What are the components of a triglyceride molecule?

Answer 20

Glycerol and three fatty acids

Question 21

What is the structural representation of a triglyceride?

Answer 21

Glycerol head and fatty acid tails

Question 22

What characterizes saturated fatty acids?

Answer 22

They do not have double bonds between carbon atoms

Question 23

What characterizes unsaturated fatty acids?

Answer 23

They have double bonds between carbon atoms

Question 24

Fill in the blank: Saturated fatty acids are more likely to be _______ at room temperature.

Answer 24

solid

Question 25

Fill in the blank: Unsaturated fatty acids are more likely to be _______ at room temperature.

Answer 25

liquid

Question 26

What is the effect of double bonds on the structure of unsaturated fatty acids?

Answer 26

They are less ordered and not so closely compacted

Question 27

What is the formula for the formation of a triglyceride?

Answer 27

Glycerol + 3 Fatty Acids → Triglyceride + 3 Water

Question 28

True or False: Saturated fatty acids contain double bonds.

Answer 28

False

Question 29

True or False: Unsaturated fatty acids are typically solid at room temperature.

Answer 29

False

Question 30

What is the mass to energy ratio of triglycerides?

Answer 30

Low mass to energy ratio ## Footnote This makes triglycerides good stores of energy.

Question 31

Why do triglycerides not affect the water potential of a cell?

Answer 31

They are insoluble in water ## Footnote This property allows for energy storage without impacting cellular water balance.

Question 32

What is the hydrogen to oxygen ratio in triglycerides compared to carbohydrates?

Answer 32

High hydrogen to oxygen ratio, not 2:1 ## Footnote This makes triglycerides a good source of water when broken down.

Question 33

What characterizes omega-3 fatty acids?

Answer 33

They are unsaturated ## Footnote Unsaturated fatty acids contain one or more double bonds.

Question 34

What defines an unsaturated fatty acid?

Answer 34

Double bond(s) between carbon atoms within the hydrocarbon chain ## Footnote This structure affects the physical properties of the fatty acid.

Question 35

What is the first step in the emulsion test for lipids?

Answer 35

Place a small amount of the sample into a test tube with ethanol and shake ## Footnote This allows the fat to dissolve in the non-polar solvent.

Question 36

What indicates the presence of fat in the emulsion test?

Answer 36

A cloudy white emulsion of fat droplets ## Footnote This forms when water is added to the mixture after shaking.

Question 37

List the steps to show that a seed contains lipids using the emulsion test.

Answer 37

* Crush/grind the seed * Mix with ethanol/alcohol and shake * Add water and shake * Observe for a cloudy white emulsion ## Footnote These steps demonstrate the presence of lipids.

Question 38

What is the primary component of all membranes?

Answer 38

Phospholipids ## Footnote They play a crucial role in cell membrane structure.

Question 39

How does the structure of phospholipids differ from triglycerides?

Answer 39

One fatty acid is replaced by a phosphate group ## Footnote This results in a molecule with two fatty acids and one phosphate group.

Question 40

What forms when phospholipids are mixed with water?

Answer 40

Micelles ## Footnote Phospholipids form droplets in aqueous environments.

Question 41

What are the characteristics of the phosphate group in phospholipids?

Answer 41

Has a negative charge (polar) ## Footnote This contrasts with the non-polar fatty acid tails.

Question 42

Describe the arrangement of phospholipids in water.

Answer 42

Hydrophobic tails face each other, hydrophilic heads face water ## Footnote This arrangement forms a bilayer structure essential for cell membranes.

Question 43

What is the main function of the phospholipid bilayer?

Answer 43

Forms the basis of the cell membrane ## Footnote This structure regulates the movement of substances in and out of the cell.

Question 44

What is removed and replaced in the formation of phospholipids compared to triglycerides?

Answer 44

Fatty acid is removed and replaced with a phosphate group ## Footnote This alteration creates a distinct functional group.

Question 45

True or False: You can seal the test tube with your thumb before shaking in the emulsion test.

Answer 45

False ## Footnote A bung is used to prevent spillage and ensure accurate mixing.