lipids Flashcards

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1
Q

What are the components of triglycerides?

A
  • A glycerol molecule.
  • 3 fatty acid chains.
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2
Q

What are the components of phospholipids?

A
  • A glycerol molecule.
  • A phosphate group.
  • Two fatty acid chains.
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3
Q

How are triglycerides formed? What is produced as a by-product of this reaction?

A
  • Triglycerides are formed via the condensation of one molecule of glycerol and 3 molecules of fatty acid (ie. three different condensation reactions occur.)
  • 3 molecules of water are produced by this condensation reaction.
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4
Q

Atoms involved in ester bond?

A

– COO

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5
Q

Explain what happens to glycerol and fatty acids in a condensation reaction to make a triglyceride + 3 water molecules.

A
  • Ester bond formed by condensation reaction between three OH groups on glycerol and the OH group of each fatty acid chain (releasing 3 molecules of water, leaving 3 ester bonds on triglyceride.)
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6
Q

What are the 2 groups of lipids?

A
  • Phospholipids.
  • Triglycerides.
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7
Q

What is the general formula of a fatty acid?

A
  • (RCOOH)
  • (R means varibale group - the number of carbons and hydrogens can change.)

() - extra for clarification

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8
Q

FInish the sentence.

The R group of a fatty acid can be ……… or ……….

A
  • Saturated
  • Unsaturated.
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9
Q

Definition of: saturated fatty acids.

A
  • The hydrocarbon chain has only single bonds between carbons.
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10
Q

Definition of: unsaturated fatty acids.

A
  • The hydrocarbon chain consists of at least one double bond between carbons.
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11
Q

In phospholipids, what are one of the fatty acids of the triglyceride substituted by.

A
  • Substituted by a phosphate- containing group.
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12
Q

Why do triglyceride’s structure help them store energy well?

A
  • Due to the large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms.
    (those carbon-hydrogen bonds store a lot of energy.)

() - extra info for clarification.

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13
Q

What structure do triglyceride’s have that allow them to be a “metabolic water source?”

A
  • Molecules have a high ratio of hydrogen to oxygen atoms - act as metabolic water source.
  • Triglycerides can release water when oxidised (essential for animals in desert.)
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14
Q

What is meant when we say triglycerides are non-polar molcules, how does this help them?

A
  • Triglycerides non-polar (have no chargee) making them insoluble in water (also because they are large= insoluble.)
  • A large amount can be stored/ won’t affect water potential. No osmosis of water into cell.
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15
Q

Why is it useful that lipids have a relatively low mass?

A
  • Helps with them being energy-storage molecules.
  • A lot of molecules can be stored without increasing the mass/ preventing movement.
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16
Q

True or False

Lipids have a relatively high mass.

A
  • False.
  • Lipids have a relatively low mass.
17
Q

True or False

Triglycerides are polar molecules.

A
  • False.
  • Triglycerides are non-polar molecules (helps them be insoluble in water.)
18
Q

Steps of emulsion test.

A
  • Dissolve sample (oil/ fat) in ethanol and shake.
  • Add distilled water and shake.
  • Positive test: white emulsion/ cloudy-white if a lipid is present.
19
Q

How are phospholipids formed?

A
  • Two fatty acid chains bond to the glycerol via two condensation reactions; resulting in 2 ester bonds formed.
20
Q

What type of head do phospholipids have? What does this mean? Why do phospholipids have this type of head?

A
  • A hydrophillic “head.”
  • The head is attracted to water.
  • Due to the fact the phosphate- (containing) group is charged.
21
Q

What does hydrophillic mean?

A
  • Section of a molecule which is attracted to water.
22
Q

Hydrophobic meaning.

A
  • Section of molecule which is repelled by water (ie. moves away from water.)
23
Q

What is the property of the fatty acid chains/ the tails in phospholipids? What does this mean? Why do phospholipids have this type of tail?

A
  • It is hydrophobic.
  • It is repelled by water.
  • Because the fatty acid chain is NOT charged.
24
Q

What are polar molecules?

A
  • Molcules that have an overall charge (ie. each end of the molecule has its own charge.)
25
Q

Can fatty acids mix with lipids, how about phosphate groups?

A
  • Phosphate groups –> repel lipids (charged.)
  • Fatty acids –> Mix/ interract with lipids.
26
Q

How do phospholipids position themselves in water?

A
  • They form double-layer in water.
  • Heads facing outwards (towards water ie. water of cytoplasm/ water in tissue in membranes.)
  • Tails facing inwards (away from water/ shielded from the aqueous environment.)
27
Q

What is the double-layer that phospholipids form when they are in water called?

A
  • Phospholipid bilayer.
28
Q

What is the property of the centre of the phosphlipid bilayer? How does this help?

A
  • Hydrophobic (repels water) so that soluble substances cannot easily pass through.
  • Creates a barrier between inside and outside of cell and allows for separation of solutions.
29
Q

What does hydrolysis of triglyceride produce?

A
  • 1 molecule of glycerol.
  • 3 fatty acid chains.
30
Q

Why is it useful to have a hydrophillic phosphate head (attracted to water?)

A
  • Helps hold the bilayer at the surface of the cell- surface membrane (because the phosphate head pulls away - attracting to water.)
31
Q

What is the name of this group (—- COOH) that is found in all fatty acids?

A
  • Carboxyl group.
32
Q

What do we call fatty acid chains that contain 1 carbon-carbon double bond only?

A
  • Mono- unsaturated chain.
33
Q

From diagrams, if there are no double bonds, how can you tell if fatty acid chain is saturated vs unsaturated?

A
  • Unsaturated: will have a kink/ bend.
  • Saturated: will be straight