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Biology Paper 1 > Biological Molecules: Lipids > Flashcards

Biological Molecules: Lipids Flashcards

1
Q

Name the group represented by COOH:

A

Carboxyl group

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2
Q

What type of R group has a C=C double bond?

A

Unsaturated

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3
Q

What type of R group has a C-C single bond?

A

Saturated

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4
Q

Describe how you would test for the presence of a lipid in a liquid sample of food: (2 marks)

A
  • Add ethanol
  • Then add water and shake
  • A positive result will be a white/milky emulsion
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5
Q

Describe how a triglyceride molecule is formed: (3 marks)

A
  • Formed from one glycerol and three fatty acids
  • Condensation reaction occurs, removing three water molecules
  • Ester bonds form
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6
Q

What is a fatty acid made up of?

A

Hydrocarbon chain attached to a carboxyl group.

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7
Q

What is the general structure of a fatty acid?

A

RCOOH

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8
Q

What is a triglyceride molecule made up of?

A

3 fatty acids
1 glycerol molecule

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9
Q

What are the two types of lipids?

A

Triglycerides
Phospholipid

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10
Q

What is an ester bond?

A

The bond between a glycerol and fatty acid

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11
Q

Why are triglycerides not polymers?

A

Because they are formed of 3 fatty acids and one glycerol molecule, not repeating units of a single monomer.

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12
Q

Name the type of reaction used to break down phospholipids to release phosphate.

A

Hydrolysis

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13
Q

Adding fatty acids into a solution causes the pH of that solution to decrease. Suggest why:

A
  • Fatty acids are acids.
  • A higher concentration of acid in a solution causes the pH to decrease (become more acidic).
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14
Q

What is a monounsaturated fatty acid?

A

An unsaturated fatty acid that only has one double bond between its carbon atoms.

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15
Q

What is a polyunsaturated fatty acid?

A

An unsaturated fatty acid that has more than one double bond between its carbon atoms.

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16
Q

What is the difference between a monounsaturated fatty acid and a polyunsaturated fatty acid?

A

Monounsaturated = Only one double bond between carbon atoms.
Polyunsaturated = More than one double bond between carbon atoms.

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17
Q

Fats, like butter, are made up of ____________ fatty acids.

A

Saturated

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18
Q

Oils, like vegetable oil, are made up of ___________ fatty acids.

A

Unsaturated

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19
Q

Describe the structure of saturated fatty acids:

A

Straight, parallel hydrocarbon chains

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20
Q

Describe the structure of unsaturated fatty acids:

A

Bends in hydrocarbon chains.

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21
Q

Why do triglycerides with saturated fatty acids, like butter, form a solid block at room temperature?

A
  • They have straight, parallel hydrocarbon chains
  • Meaning they don’t take up a lot of space and can be packed tightly together.
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22
Q

Why can’t triglycerides with unsaturated fatty acids, like vegetable oil, form a solid block at room temperature?

A
  • They have bends in their hydrocarbon chains
  • Meaning they take up a lot of space and can’t be packed tightly together
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23
Q

Saturated fats are _______ at room temperature.

A

Solid

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24
Q

Unsaturated fats are _______ at room temperature.

A

Liquid

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25
Q

Butter is a/an __________ fat.

26
Q

Vegetable oil is a/an _________ fat.

A

Unsaturated

27
Q

A fatty acid with no double bonds between carbon atoms is described as _____________.

28
Q

A fatty acid with at least one double bond between carbon atoms is described as _____________.

A

Unsaturated

29
Q

A fatty acid with one double bond is called a __________ fatty acid.

A

Monounsaturated

30
Q

What are the 3 properties of fatty acids:

A
  • High ratio of hydrogen and carbons to oxygens
  • Large
  • Non-polar
31
Q

Why are triglycerides non-polar?

A

Their non-polar region is much bigger than their polar region

32
Q

What happens when a triglyceride is dropped on water? Why?

A
  • It sits on top of the water
  • Water is polar, triglyceride is non-polar
  • Polar molecules and non-polar molecules do not mix
  • Triglycerides are insoluble in water
33
Q

Why are triglycerides hydrophobic?

A
  • Triglycerides are non-polar, water is polar
  • Non polar and polar molecules do not mix
  • Triglycerides are insoluble in water
34
Q

Why are triglycerides a good energy source?

A

They have a high: carbon and hydrogen: oxygen

35
Q

Explain how storage of fat in the hump of a camel can help it survive in the desert:

A
  • Fat in the hump is stored as triglycerides.
  • During respiration triglycerides are used to produce ATP, also releasing water.
  • The high C&H:O means many water molecules can be produced.
  • Large amounts of energy released will provide energy for camel when food is scarce.
  • Low mass:energy means lots of energy is stored in a small space.
36
Q

Describe the structure of a phospholipid:

A
  • 3 glycerol molecules
  • 2 fatty acid tails
  • 1 phosphate group
37
Q

The fatty acid tails in a phospholipid are attached to the glycerol molecule with _______ bonds.

38
Q

State 4 similarities between triglycerides and phospholipids:

A
  • Both contain ester bonds
  • Both contain glycerol
  • Both have fatty acid tails
  • Both have hydrogen, oxygen and carbon
39
Q

State 2 differences between triglycerides and phospholipids:

A
  • Phospholipids contain a phosphate group, triglycerides do not.
  • Phospholipids have two fatty acid tails, triglycerides have three fatty acid tails.
40
Q

Why are triglycerides insoluble in water?

A

They have a non-polar region (hydrophobic).

41
Q

What are the two functions of phospholipids:

A
  • Make cell surface membranes flexible
  • Enable cell recognition
42
Q

Explain how phospholipids make cell-surface membranes flexible:

A
  • Phospholipids contain a mix of saturated and unsaturated fatty acids.
  • Unsaturated fatty acids cant be packed tightly together, so they form gaps in the cell surface membrane.
  • Allows phospholipids to tilt side-side
43
Q

Explain how phospholipids allow cell recognition:

A
  • Can combine with a carbohydrate to produce glycolipids.
  • Glycolipids prove to our immune system that it is a self-cell.
44
Q

Name the three structures that phospholipids can form in water:

A
  • Micelle
  • Monolayer
  • Bilayer
45
Q

Why are phospholipids insoluble in water?

A

Hydrophobic tails

46
Q

Why can small molecules like O and CO2 pass through the lipid bilayer without using a transport protein?

A

Unsaturated fatty acids create gaps in the bilayer which makes the cell surface membrane flexible so small molecules can pass through.

47
Q

Why are triglycerides and phospholipids soluble in alcohol?

A
  • Ethanol has a polar and a non-polar region
  • So ethanol is able to mix with polar and non-polar substances
48
Q

What are fatty acid tails made up of?

A

Hydrocarbons

49
Q

What property of triglycerides makes them insoluble in water?

A

Hydrophobic fatty acid tails

50
Q

What are the two types of fatty acids?

A

Saturated
Unsaturated

51
Q

Saturated fatty acids have a _____ CC bond.

52
Q

Unsaturated fatty acids have a _____ CC bond.

53
Q

What causes unsaturated fatty acids to kink?

A

Double CC bond.

54
Q

Where are ester bonds formed?

A

Glycerol molecule
Fatty acid

55
Q

Triglycerides are formed through a ______ reaction.

A

Condensation

56
Q

Where are phospholipids found?

A

Cell membranes

57
Q

What is the difference in the structure of triglycerides and phospholipids?

A

Triglycerides : 1 glycerol, 3 fatty acids
Phospholipids : 1 glycerol, 2 fatty acids, 1 phosphate group

58
Q

The phosphate group in phospholipids is hydro_____.

A

Hydrophilic

59
Q

Why are triglycerides good storage molecules?

A

1) Long hydrocarbon fatty acid tails contain lots of chemical energy = Lots of energy is released when they are broken down
2) Insoluble in water = Wont affect cells water potential

60
Q

The phospholipid heads are hydro____ and their tails are hydro____.

A

Hydrophilic
Hydrophobic

61
Q

The centre of the phospholipid bilayer is ______.

A

Hydrophobic

Biology Paper 1 (32 decks)

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