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As-Level Biology - Biological Molecules - Moss > Lipids > Flashcards

Lipids Flashcards

1
Q

Why are lipids different from proteins and carbohydrates?

A

They’re not polymers formed from long chains of monomers

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2
Q

What are Lipids made from?

A

Hydrocarbons

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3
Q

What are hydrocarbons?

A

Molecules that contain only hydrogen and carbon atoms

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4
Q

What are the 2 types of lipids?

A

Triglycerides

Phospholipids

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5
Q

What is the structure of triglycerides?

A

1 molecule of glycerol with 3 fatty acids attached

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6
Q

What is the structure of fatty acid molecules?

How does it make lipids insoluble in water?

A

Have long ‘tails’ made of hydrocarbons

Tails are ‘hydrophobic’

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7
Q

What does hydrophobic mean?

A

They repel water molecules

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8
Q

What are the 2 types of fatty acid?

A

Saturated

Unsaturated

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9
Q

What is the difference between the 2 types of fatty acid?

A

Saturated don’t have double bonds between carbon atoms

Unsaturated do

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10
Q

What are saturated fatty acids saturated with?

A

Hydrogen

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11
Q

What causes the chain to kink in unsaturated fatty acids?

A

Double bonds between carbon atoms

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12
Q

What reaction forms a triglyceride?

A

Condensation

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13
Q

How is a triglyceride formed?

A

Ester bond forms between a fatty acid and a glycerol molecule

Releasing a molecule of water

Happens twice more

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14
Q

What are the lipids found in cell membranes?

A

Phospholipids

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15
Q

What is the structure of a phospholipid?

A

Glycerol molecule

2 fatty acids

Phosphate group

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16
Q

What does the phosphate group do in the phospholipid?

A

Attracts water

17
Q

What does hydrophilic mean?

A

Attracts water

18
Q

What are triglycerides mainly used as?

A

Energy storage molecules

19
Q

Why are triglycerides good for storage?

A

Long hydrocarbon tails of fatty acids contain lots of chemical energy

20
Q

Why do the triglycerides bundle together as insoluble droplets in cells?

A

Fatty acid tails are hydrophobic

Tails face inwards, shielding themselves from water with their glycerol heads

21
Q

What makes up the bilayer of cell membranes?

A

Phospholipids

22
Q

What do cell membranes control?

A

What enters and leaves the cell

23
Q

Why do phospholipids form a double layer?

Why does the membrane act as a barrier to water?

A

Phospholipid heads are hydrophilic and tails are hydrophobic so heads face out towards water on either side

Centre of bilayer is hydrophobic so water-soluble substances can’t easily pass through it

24
Q

What test is used to test for lipids?

A

Emulsion test

25
Q

How do you carry out the emulsion test?

A

Shake test substance with ethanol for about a minute

Pour solution into water

26
Q

What does a milky emulsion in the emulsion test identify?

A

Lipid is present

As-Level Biology - Biological Molecules - Moss (8 decks)

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