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Bio A-level > Unit 1 Biological Molecules (Lipids) > Flashcards

Unit 1 Biological Molecules (Lipids) Flashcards

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1
Q

What are triglycerides?

A

Triglycerides are a type of lipid that are mainly used as energy strorage molecules.

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2
Q

How are triglycerides formed?

A

Triglycerides are formed from the condensation of 1 molecule of glycerol and 3 molecules of fatty acids.

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3
Q

What is formed between the glycerol and fatty acids chains?

A

An ester bond is formed between the glycerol and fatty acid chains.

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4
Q

What is released per ester bond made?

A

Per ester bond made,1 molecule of water is released.

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5
Q

How many molecules of water are released, per triglyceride?

A

3 molecules of water are released per triglyceride formed.

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6
Q

Describe the structure of fatty acids?

A

Fatty acids have long ‘tails’.

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7
Q

What are the tails of fatty acids made of?

A

Fatty acids have tails made of a chain of hydrocarbons containing 4-36 carbon atoms.

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8
Q

Describe the Hydrocabon tails of fatty acids?

A

The hydrocarbon tail is variable but most fatty acids have a hydrocarbon tail that contains 12-18 carbon atoms.

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9
Q

Where does Glycerol link to with the fatty acids?

A

Glycerol links to the central carbon atom on fatty acids.

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10
Q

What are the 2 main points about the fatty acids in a triglyceride? step 1

A

1) The fatty acids in a triglyceride can be similar or dissimilar to each other.

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11
Q

What are the 2 main points about the fatty acids in a triglyceride? step 2

A

2) The fatty acids can be saturated or unsaturated.

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12
Q

What is stored in the fatty acid tails?

A

Chemical energy is stored in the fatty acid tails.

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13
Q

What happens as a result of triglycerides breaking down?

A

As triglycerides break down, lots of energy is released.

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14
Q

What is the fact about the amount of energy in lipids compared to carbohydrates?

A

Carbohydrates contain half the amount of energy per gram compared to lipids

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15
Q

What is the relation between triglycerides in comparison to water?

A

Triglycerides are insoluble in water due to the fatty acid tails being hydrophobic.

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16
Q

Since triglycerides are insoluble in water what is this in relation to the water potential?

A

The cell’s water potential is not changed in relation to the fatty acids tails being hydrophobic.

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17
Q

Why is it important that the cell’s water potential in relation to triglycerides?

A

This means that the cell’s water potential is not affected by the triglycerides as a result the water being unable to enter the cell via osmosis.

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18
Q

What would happen if too much water entered the cell?

A

The cell would become swollen and would burst.

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19
Q

Too much water entering the cell is also known as?

A

Osmotic Shock

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20
Q

Why are the insoluble triglycerides formed as droplets?

A

The hydrophobic fatty acid tails face inwards which forms a droplet.

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21
Q

What type of energy do triglycerides store?

A

Chemical energy

22
Q

What is the similarity between Phospholipids and Triglycerides?

A

They are both composed of a one glycerol molecule attached to 3 molecules of fatty acids.

23
Q

What is the difference between Phospholipids and Triglycerides?

A

Phospholipid has 2 molecules of fatty acids with the third molecule of fatty acid being replaced with a hydrophilic phosphate group.

24
Q

What is the term used when the phospholipid has an hydrophobic and hydrophilic part?

A

An amphipathic molecule

25
Q

In phospholipids where do the hydrophobic tails face?

A

In Phospholipids the hydrophobic tails faces inwards in the bilayer within a membrane.

26
Q

What type of substances can’t easily pass through the membrane within the bilayer of the phospholipid?

A

Water-soluble substances can’t pass through the membrane.

27
Q

Which way does the hydrophilic phosphate head face?

A

Outwards

28
Q

What state are saturated fatty acids at room temperature?

A

Solids

29
Q

What negative impact can saturated fats have on humans?

A

There is an increased risk of heart failure as well as cardiovascular disease.

30
Q

Give 3 foods with large proportion of saturated fats?

A

Butter, cheese and creams

31
Q

What feature do saturated fats have in a chain?

A

The fatty acids are joined together in single bonds within a chain.

32
Q

What feature do unsaturated fats have in a chain?

A

The fatty acids are joined together in at least one double bond with other single bonds.

33
Q

Give an example of an unsaturated fats?

A

Cooking Oils

34
Q

What are phospholipids?

A

A type of lipid that forms a bilayer.

35
Q

What are the main component of cell membranes?

A

Phospholipids

36
Q

What is the role of a phospholipid?

A

They are responsible for what goes in and out of a cell

37
Q

What feature is only present within a saturated fatty acid chain?

A

There are only single carbon atoms bonded together to form a chain.

38
Q

What is the test for lipids called?

A

The emulsion test

39
Q

What is an emulsion?

A

Small droplets of a substance are suspended within a solution.

40
Q

What are the steps within the emulsion test?

A

1) Place the sample in a boiling with ethanol.
2) Shake well and leave the test tube upright for 2-3 mins.
3) Pour the solution into a boiling tube containing distilled water.

41
Q

If a lipid is present within the test tube what forms?

A

A distinct white and milky layer forms.

42
Q

Describe how triglycrides are formed? (3 steps)

A

1) Triglyceride is formed from the condensation reaction between the hydroxyl group on the glycerol and the carboxyl group on the fatty acids.

43
Q

Describe how triglycerides are formed (2nd step)?

A

2) An ester bond between the hydroxyl groupa nd the carboxyl bond forms.

44
Q

Describe how triglycerides are formed (3rd step)?

A

3) For each ester bond made there are 3 molecules of water produced.

45
Q

How do phospholipids interact with water? (1st step)

A

1) The phosphate group of the phospholipid is water-soluble so its is hydrophylic.

46
Q

How do phospholipids interact with water? (2nd step)

A

2) Therefore the phospholipids have only the phosphate group as hydrophilic which means the rest of the phospholipid is hydrophobic.

47
Q

How do phospholipids interact with water?

A

3) This means that phospholipids can interact with water as water is a polar molecule which can interact with the negative charged phosphate head.

48
Q

Compare saturated and unsaturated fatty acids in their structure? (1st step)

A

1) Both saturated and unsaturated fatty acid chains are made up of hydocarbon chains.

49
Q

Compare saturated and unsaturated fatty acids in their structure? (2nd step)

A

2) The saturated fatty acid chains are made up of one or more double bonds along with the other single bonds.

50
Q

Compare satturated and unsaturated fatty acids in their structure? (3rd step)

A

3) The unsaturated fatty acid chains are made up of just single bonds.

51
Q

Compare satturated and unsaturatted fatty acids in their structure? (4th step)

A

4) The double bonds in the saturated fatty acids cause the carbon atoms to kink which means unsaturated fatty acids are unable to pack close and tightly together.

52
Q
A

Bio A-level (16 decks)

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