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Biological Molecules - Biology - A Level > 4. Lipids > Flashcards

4. Lipids Flashcards

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1
Q

Give an example of a lipid?

A

Triglyceride.

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2
Q

What is the structure of a triglyceride?

A

One molecule of glycerol with 3 fatty acids attached to it.

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3
Q

What is the structure of a fatty acid molecule?

A

Long tails made of hydrocarbons.
The tails are hydrophobic (repel water) makes them insoluble in water.
All have the same basic structure but hydrocarbon tail varies.

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4
Q

What is the basic structure of a fatty acid? diagram

A

Carbon atoms links fatty acid to glycerol.

Variable R group hydrocarbon tail.

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5
Q

How is a triglyceride formed?

A

When a fatty acid joins to glycerol molecule.
Ester bond is formed, a molecule of water is releases - its a condensation reaction.
Process happens twice more to from triglycerides.

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6
Q

Name the 2 kinds of fatty acid?

A

Saturated.
Unsaturated.
Difference is in their hydrocarbon tails - r group.

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7
Q

What are saturated fatty acids?

A

Don’t have any double bonds between their carbon atoms.
Fatty acid is saturated with hydrogen - maximum saturation.

Form straight chains

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8
Q

What are unsaturated fatty acids?

A

Have atleast one double bond between carbon atoms, causing chain to kink.

More double bonds the more it’s bent

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9
Q

What are the lipids found in cell membranes called?

A

Phospholipids.

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10
Q

What are phospholipids?

A

Similar to triglycerides except one of the fatty acid molecules is replaced by phosphate group.

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11
Q

What is a phosphate group?

A 
Its hydrophilic (attracts water).
The fatty acid tails are hydrophobic (repel water).
This is important in the cell.
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12
Q

What are triglycerides mainly used for?

A

Energy storage.

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13
Q

Why are triglycerides good for energy storage?

A

Long hydrocarbon tails of the fatty acids contain lots of chemical energy - lots of energy released when broken down.
They’re insoluble so don’t affect water potential of the cell and cause water to enter cells by osmosis.

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14
Q

How much energy do lipids contain?

A

Twice as much energy per gram as carbohydrates.

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15
Q

What do the triglycerides clump into?

A

A insoluble droplets in cells because the fatty acid tails are hydrophobic - tails face inwards, shielding them from the water with their glycerol heads.

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16
Q

What do phospholipids make up?

A

The bilayer of cell membranes.

Cell membranes controls what enters and leaves the cell.

17
Q

Structure of phospholipids?

A

Heads are hydrophilic and tails ate hydrophobic so they form double later with heads facing out towards water.
Centre of bilayer is hydrophobic so water-soluble substances can’t pass through it easily.

18
Q

What is the emulsion test for lipids?

A

To find fat in a food use the emulsion test.
Shake the test substance with ethanol for 1 minute so it dissolves, then pour solution into water.
Lipid will show up as milky emulsion.
More lipid=more noticeable milky colour is.

19
Q

What are phospholipids made up of ?

A

1 glycerol

2 fatty acids

1 inorganic phosphate

20
Q

What TYPE of properties do phospholipids have ?

A

Amphiphillic

21
Q

What are the phospholipids droplets which exclude water, called ?

A

Micelle

And

Bilayers

22
Q

What elements do lipids contain ?

A

Carbon

Hydrogen

Oxygen

23
Q

Example of triglycerides

A

Fats - solid at room temp

Oils - liquid at room temp

24
Q

How many ester bonds form in triglycerides

A

3

After water is removed

25
Q

Hydrolysis of triglycerides

A

Add 3 molecules of water to break ester bond

This produces 3 fatty acid molecules and 1 glycerol molecule

26
Q

What does saturation refer to ?

A

Hydrogen

More “full of hydrogen” the hydrocarbon chain is the more saturated fatty acid is

Not fully saturated then doubly bonds form between carbon atoms

27
Q

What will a triglycerides with all saturated fatty acids forms ?

A

Fat

Solid

28
Q

Mono saturated fatty acid

A

1 carbon double bond

29
Q

What will triglycerides be with all unsaturated fatty acids?

A

Oil

Can’t compact as tight together

Biological Molecules - Biology - A Level (20 decks)

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