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Biology 3.1 Biological molecules > lipids > Flashcards

lipids Flashcards

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1
Q

what is a lipid?

A

a triglyceride; it is made up of one glyercol bonded to three fatty acid chains via ester bonds

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2
Q

why are lipids not polymers?

A

they are made up of chemical units not monomers (no repeated units)

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3
Q

what is a monoglyceride?

A

a glycerol attached to one fatty acid chain via an ester bond

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4
Q

what is the structural formula for glycerol?

A

H
I
H – C – OH
I
H – C – O H
I
H – C – OH
I
H

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5
Q

what is the hydroxyl functional group in glycerol?

A

-OH

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6
Q

what are fatty acids made of?

A

a carboxyl group (-COOH) and a hydrocarbon

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7
Q

what is a hydrocarbon?

A

a compound only made of hydrogen and carbon

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8
Q

what does R represent in the fatty acid structural formula?

A

hydrocarbon

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9
Q

what can vary about the R group of fatty acids?

A

they can be saturated or unsaturated

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10
Q

what is teh difference between saturated and unsaturated hydrocarbons?

A

saturated means single bonds and unsaturated are double bonds

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11
Q

what does polyunsaturated mean?

A

more than one double bond in the chain

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12
Q

why can’t triglycerides dissolve in water?

A

they are non-polar

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13
Q

what can lipids be dissolved in?

A

ethanol

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14
Q

write a description of a condensation reaction to form a monoglyceride from a glycerol and fatty fatty acid?

A

the hydroxyl group of glycerol reacts with the carboxyl group of the fatty acid

water is removed to form an ester bond between the glycerol and fatty acid

a monoglyceride has been produced and one molecule of water

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15
Q

what is the test for lipds?

A

emulsion test

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16
Q

how does the emulsion test work?

A

add ethanol, shake , add water , shake

reagents are ethanol and water

17
Q

what is the positive result in the lipids test?

A

milky white emulsion

18
Q

what is a phospholipid?

A

glycerol bonded to two fatty acid chains and a phosphate ion (negative charge)

19
Q

why can phospholipids be dissolved in water?

A

a phosphate ion has a negatice charge (polar)

20
Q

how are phospholipids structured?

A

head and two tails

21
Q

what is the head of a phospholipid made up of and what are its properties?

A

a phosphate ion and glycerol
negative charge

HYDROPHILIC (love water) face outward towards the intracellular and extracellular fluid

22
Q

what are the tails of phospholipids made of and what are the properties?

A

fatty acid chains
no charge
not water soluble

HYDROPHOBIC (don’t dissolve in water)

23
Q

what are cell membranes and organelle membranes made from?

A

phospholipid bilayer

24
Q

what is the phospholipid bilayer?

A

two layers of phospholipids that make up the cell or plasma membrane.

25
Q

what is a significant point about the phospholipid bilayer?

A

no charge- so charged ions cannot pass through

26
Q

what can/ can’t get across a phospholipid bilayer?

A

small non-polar molecules that are lipid soluble

not polar molecules that can dissolve in water

27
Q

what are the roles of lipids?

A

-cell membranes
-source of energy (when oxidised they provide more than twice the energy as the same mass of carbohydrate and release valuable water)
-waterproofing (since they are insoluble)
-insulation (slow conductors of heat and help retain body heat)
-protection

28
Q

why are triglycerides such a good source of energy?

A

high ratio of energy- storing carbon-hydrogen bonds to carbon atoms

29
Q

why are triglycerides good storage molecules?

A

have low mass to energy ratio, making them good storage molecules because much energy can be stored in a small volume- beneficial to animals as it reduces the mass they have to carry as they move around

30
Q

what is the benefit of triglycerides being insoluble in water?

A

being large, non-polar molecules makes them insoluble in water
so their storage does not affect osmosis in cells or the water potential of them

31
Q

how are triglycerides an important source of water?

A

as they have high ratio of hydrogen to oxygen atoms, triglycerides release water when oxidised

Biology 3.1 Biological molecules (9 decks)

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