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B 1,2 > Lipids > Flashcards

Lipids Flashcards

1
Q

What are the characteristics of lipids?

A
  • They contain carbon, hydrogen and oxygen.
  • Proportion of oxygen to carbon and hydrogen is smaller than in carbohydrates
  • Insoluble in water
  • They are soluble in organic solvents such as alcohol and acetone.
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2
Q

What are triglycerides?

A

Lips that have one molecule of glycerol with three fatty acids attached to it.

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3
Q

What reaction forms triglycerides?

A

Condensation Reactions.

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4
Q

How are triglycerides formed?

A
  • Fatty acid joins a glycerol molecule, an ester bond is formed and a molecule of water is released.
  • Reaction occurs twice more to form a triglyceride.
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5
Q

What bonds do the fatty acids form?

A

Each fatty acid forms an ester bond with glycerol in a condensation reaction.

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6
Q

What is the role of phospholipids in the cell membrane?

A

Phospholipids in the cell membrane serve the following purposes:
They contribute to
• The Flexibility of the Cell Membrane.
• Transfer of lipid soluble substances across them.

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7
Q

What are some key roles of phospholipids?

A
  • Source Of Energy
  • Waterproofing
  • Protection
  • Insulation
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8
Q

How do phospholipids serve as a source of energy?

A
  • When oxidised, lipids provide twice the energy as the same amount of carbohydrates.
  • Release Water
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9
Q

How do phospholipids serve as protection?

A

Fat is stored around delicate organs, this provides a layer of protection.

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10
Q

How do phospholipids serve as a source of insulation ?

A

• Fats are bad conductors of heat, can be stored under the body surface to retain body heat.

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11
Q

What role do phospholipids serve in nerve cells?

A

• Act as electrical insulators in the myelin sheath around nerve cells.

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12
Q

What reaction breaks down triglycerides?

A

Hydrolysis

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13
Q

What are the products of hydrolysis of triglycerides?

A
  • Three Fatty Acids

* Glycerol

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14
Q

What are phospholipids?

A

Phospholipids are membranes which consist of glycerol, two fatty acids and a phosphate group.

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15
Q

What causes variation in the triglycerides?

A

• Differences in the triglycerides come from variations in the fatty acids, as all glycerol molecules in triglycerides are the same.

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16
Q

What are the two types of fatty acids?

A
  • Saturated

* Unsaturated

17
Q

How do saturated fatty acids differ to unsaturated fatty acids?

A
  • Saturated fatty acids don’t have any double bonds between their carbon atoms.
  • Unsaturated fatty acids have at least one double bond between carbon atoms
18
Q

What are triglycerides used for?

A

Energy Storage

19
Q

How are triglycerides suited to carrying out their function?

A
  • Triglycerides a high ratio of carbon hydrogen atoms to carbon atoms, making them a good energy source ( Carbon hydrogen stores energy ).
  • Triglycerides have a low mass to energy ratio, making them very good at storage, because much can be stored in a small space.
  • Insoluble, so they do not affect water potential, and cause water to enter the cells by osmosis.
  • Long hydrocarbon tails contain lots of chemical energy, when broken down they release a lot of energy.
  • High ratio of hydrogen to oxygen atoms, they release water when oxidised, and therefore are an excellent source of water.
20
Q

What are the two parts that make up a phospholipid?

A
  • Hydrophillic Head

* Hydrophobic Tail

21
Q

What are polar molecules?

A

Molecules that have two ends that behave differently.

22
Q

What function do phospholipids serve in the cell membrane?

A

They make up the bi-layer of cell membranes.

23
Q

How are phospholipids adapted to their purpose?

A
  • Heads are hydrophilic, and tails are hydrophobic, so they form a double layer, with their heads facing out towards the water.
  • Centre of bi-layer is hydrophobic, so water soluble substances cannot pass easily through it, membrane therefore acts as a barrier.
  • They can form glycolipids by combining with carbohydrates inside the cell surface membrane.
24
Q

What is the test for lipids?

A

Emulsion Test.

25
Q

What is the process of the emulsion test?

A
  • Shake the test substance with ethanol for a minute so that it dissolves, then pour the water solution into water.
  • Lipids will show up as a milky emulsion.
  • The more lipid there is, the more noticeable the milky colour will be.
26
Q

How do phospholipids differ to triglycerides?

A

One of the fatty acid molecules is replaced by a phosphate group.

27
Q

What parts of the phospholipid are hydrophillic, and hydrophobic?

A
  • Phosphate group is hydrophilic.

* Tails are hydrophobic.

B 1,2 (26 decks)

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