Lipids Flashcards

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1
Q

What are lipids NOT?

A

Polymers

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2
Q

What are the characteristics of lipids?

A

-contain hydrogen, carbon and oxygen
-insoluble in water
-soluble in organic solvents

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3
Q

What are the main groups of lipids called?

A

triglycerides and phospholipids

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4
Q

What are the roles of lipids?

A

-source of energy
-waterproofing
-insulation
-protection
-cell membranes

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5
Q

How are lipids a source of energy?

A

when oxidised, lipids provides x2 the energy as the same mass of carbohydrate and release valuable water

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6
Q

How do lipids provide waterproofing?

A

Insoluble in water

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7
Q

How do plants and insects use lipids as waterproofing?

A

waxy, lipid cuticles that conserve water

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8
Q

How do mammals use lipids as waterproofing?

A

produce oily secretion from sebaceous glands in skin

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9
Q

How do lipids act as insulation?

A

fats are slow conductors of heat and when stored below body surface, they help retain body heat

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10
Q

How are lipids used in nerve cells?

A

In the myelin sheath as an electrical insulation

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11
Q

How do lipids act as production?

A

fat often stored around delicate organs, e.g kidneys

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12
Q

What state are fats at room temperature?

A

Solid

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13
Q

What state are oils at room temperature?

A

Liquid

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14
Q

How do lipids function in the cell membrane?

A

phospholipids contribute to flexibility and transfer of lipid-soluble substances

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15
Q

What forms a triglyceride?

A

Three fatty acids and one glycerol molecule

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16
Q

Where do bonds form in a condensation reaction for a triglyceride?

A

each fatty acid forms an ester bond with glycerol

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17
Q

What bond is involved in triglycerides?

A

Ester

18
Q

What group do ALL fatty acids have?

A

-COOH

19
Q

What is a saturated fatty acid?

A

Fatty acid with no carbon-carbon double bond

20
Q

What makes a molecule saturated?

A

All carbon atoms linked to maximum possible number of hydrogen atoms
No double carbon-carbon bond

21
Q

What is an unsaturated fatty acid?

A

Fatty acid with a carbon-carbon double bond

22
Q

What happens to the fatty acid chain when it is unsaturated?

A

Kinks/Bends

23
Q

What are the properties of a triglyceride?

A

-high ratio of energy storing carbon hydrogen bonds to carbon atoms
-low mass to energy ratio
-large, non polar molecules: insoluble
-high ratio of hydrogen to oxygen atoms

24
Q

What is the importance of a high ratio of energy storing carbon hydrogen bonds to carbon atoms in a triglyceride?

A

good source of energy

25
Q

What is the importance of a low mass to energy ratio in triglycerides?

A

good storage molecule- more energy stored in small volume

26
Q

What is the importance of triglycerides being insoluble?

A

storage doesn’t affect water potential or draw in water by osmosis

27
Q

What is the importance of high ratio of oxygen to hydrogen atoms in triglycerides?

A

release water when oxidised: important source of water

28
Q

What is a phospholipid composed of?

A

two fatty acids
glycerol molecule
phosphate molecule

29
Q

What two parts are phospholipids divided into?

A

Hydrophilic head
Hydrophobic tail

30
Q

What section of the phospholipid is hydrophilic?

A

phosphate molecules attract water

31
Q

What section of the phospholipid is hydrophobic?

A

fatty acid molecules repel water

32
Q

What does hydrophilic mean?

A

is attracted to water

33
Q

What does hydrophobic mean?

A

orients away from water

34
Q

How do polar phospholipid molecules position themselves in water?

A

hydrophilic heads are as close to water as possible and hydrophobic tail are as far away water as possible

35
Q

What are the properties of phospholipids?

A

-polar molecules
-hydrophilic head
-hydrophobic tail
-can form glycolipids

36
Q

What is the importance of phospholipids being polar?

A

in aqueous environment phospholipid molecules form bilayer in cell surface membrane-hydrophobic barrier formed between inside and outside of cell

37
Q

What is the importance of glycolipids?

A

cell recognition

38
Q

How do we test for lipids?

A

-dry/grease free test tube
-add 5cm ethanol to 2cm3 food sample
-shake tube thoroughly
-add 5cm3 water shake gently

39
Q

What indicates the presence of a lipid?

A

milky-white emulsion

40
Q

What do reagents are used to test for lipids?

A

Ethanol and water