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My Biology > lipids > Flashcards

lipids Flashcards

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1
Q

what are the elements present in lipids

- what is the extra element present in phospholipids

A

carbon, hydrogen, oxygen

- phosphorus

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2
Q

what are the 3 categories of lipids

A
  • triglycerides
  • phospholipids
  • sterols
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3
Q

draw a labelled diagram showing how a triglyceride is formed or broken down, and include the basic structure of a triglyceride

A

picture

  • must show glycerol and fatty acids
  • ester bond
  • must show where the water molecule comes from - OH from carboxyl end of fatty acid, H from glycerol
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4
Q

state the components of a triglyceride

A
  • 1 molecule of glycerol

- 3 molecules of fatty acids

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5
Q

what are the properties at each end of a fatty acid

A
  • CH3 methyl group
  • fat soluble
  • water insoluble
  • COOH carboxyl group
  • water soluble
  • fat insoluble
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6
Q

draw a diagram of each

  • monounsaturated fatty acids
  • polyunsaturated fatty acids
  • saturated fatty acids
A
  • mono = one double bond between carbons
  • kink at the double bond
  • poly = more than one double bond between carbons
  • kink at each double bond
  • saturated = no double bonds between carbons
  • straight chain
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7
Q

explain why saturated triglycerides are fats at rtp

explain why unsaturated triglycerides are oils at rtp

A
  • the straight chains can fit together so pack densely. this makes them solid at rtp
  • the kinks in unsaturated chains means they cannot pack tightly together. this makes them liquid at rtp
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8
Q

describe and explain why the melting point correlate with the length of the triglyceride

A
  • the melting point would be higher as the triglyceride length increases
  • more bonds means more energy is needed to break the bonds
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9
Q

what is the difference between triglycerides found in animals compared to in plants

A

plants - unsaturated

animals (but not fish) - saturated

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10
Q

draw the basic structure of a phospholipid

A
  • shows phosphate group
  • phosphoester bond
  • glycerol
  • ester bonds
  • 2 fatty acid tails
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11
Q

what are the properties at each end of the phospholipid

A

phosphate head:

  • hydrophilic
  • polar

fatty acid tails

  • hydrophobic
  • non polar
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12
Q

what is the difference between a triglyceride and a phospholipid

A

triglyceride - 3 fatty acid chains

phospholipid - 2 fatty acid chains

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13
Q

what are the bonds that hold triglycerides together

A

ester

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14
Q

how many molecules of water are formed from making one triglyceride

A

3

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15
Q

what enzyme breaks down ester bonds

A

lipase

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16
Q

describe the structure of sterols / cholesterol

A
  • complex alcohol molecules
  • 4 carbon ring structure
  • hydroxyl group is hydrophilic and the rest is hydrophobic
17
Q

list the functions of triglycerides (5)

- relate each to a property

A
  • thermal insulator
  • buoyancy - less dense than water
  • waterproof - non polar
  • protection for internal organs
  • energy store - insoluble
18
Q

list the functions of phospholipids (2)

- relate each to a property

A
  • form membrane bi layers - dual hydrophobic/philic
    hydrophobic - towards centre of bilayer, hydrophilic - towards outside of bilayer
  • found in surfactants - hydrophobic tails out of water, hydrophilic heads in water
19
Q

list the functions of cholesterol

A
  • role in formation of membranes - sticking to phospholipids

- manufactures vitamin D, steroid hormones and bile

20
Q

Explain how phospholipids form a membrane

A

Hydrophilic phosphate heads face out of the membrane - to the aqueous external environment and aqueous internal conditions.
Hydrophobic fatty acid tails point inwards away from the aqueous environments
- this is known as the phospholipid bilayer

21
Q

Describe how cholesterol affects properties of cell membranes

A
  • the hydroxyl end of cholesterol attaches to the hydrophilic phosphate head of the phospholipid
  • this reduces fluidity
  • adds stability - maintains constant fluidity over a range of temps

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