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CH112 > natural products 1 > Flashcards

natural products 1 Flashcards

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1
Q

what is a lipid ?

A

this is the term given to a water insoluble natural product isolated from plants and animal cells

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2
Q

what can lipids be divided up into and how ?

A

into polyketides and polyisoprenens , they are divided due to the way they are biosynthesised

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3
Q

how are polyketides synthesised ?

A

these are assembled of multiple units of 2 carbons

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4
Q

what are polyketides the basis for ?

A

the formation of fats , oils , waxes , prostaglandins , membrane lipids and a variety of bioactive cyclic compounds.

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5
Q

how are isporenes synthesised ?

A

they are assembled from multiple units of 5 carbons

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6
Q

what to isoprenes give rise to ?

A

fragrant plant perfumes , flavourings and steroid hormones

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7
Q

how are fats and oils formed ?

A

they are formed when long chain aliphatic carboxylic acids are esterified with glycerol

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8
Q

what is glycerol also known as ?

A

1-2-3-trihydroxylpropane

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9
Q

what are fats and oils also known as ?

A

triglycerides

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10
Q

what occurs when a triglyceride is hydrolysed with a acid or alkali ?

A

you get a glycerol molecule and 3 fatty acid molecules

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11
Q

are the R groups of the fatty acid the same ?

A

no they can be the same or different

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12
Q

Fatty acids can be saturated or unsaturated , whats the difference ?

A

saturated contains no double bond and only has single bonds , while unsaturated has double bonds and sometimes triple bonds.

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13
Q

why are the carboxylic acids in fats and oils called fatty acids ?

A

due to them being originally obtained from fats

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14
Q

what will the number of carbon atoms in a fatty acid usually be and why ?

A

normally be even as they will have been biosynthesised from several 2 units of carbons

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15
Q

what is the MP and BP of saturated chains and why ?

A

they have high MP and BP as they can pack together well as a result of numerous van der Waals so they form a stable crystal like lattice.

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16
Q

whats the MP and BP of unsaturated chains and why ?

A

they have a low MP and BP as they cannot pack together so tightly and neatly due to the cis double bonds.

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17
Q

if the chains had trans double bonds what would occur ?

A

there would be far less distribution

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18
Q

why do short chains have low MP and BP ?

A

due to the irregular gaps forming when the chain is packing

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19
Q

whats the composition of animal fats and why ?

A

they will have a mixture of triglycerides that contain a high proportion of saturated chains due derived from stearic acid and plamitic acid. having a high MP and BP they will be solid at room temp

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20
Q

whats the several biological functions of fats ?

A

they provide long term energy storage

provide thermal insulation

provide mechanical insulation to prevent injury

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21
Q

whats the composition of vegetable oils ?

A

they contain more unsaturated chains and as a result have a lower MP and are liquid at room temp

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22
Q

why is margarine more easier to spread than butter ?

A

butter contains more saturated fats compared to margarine. Therefore margarine has more double bonds and hence has a lower MP

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23
Q

if fats are hydrolysed in an alkali then what is obtained and how are they useful ?

A

you obtain a salt of the fatty acid that can be used as soaps

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24
Q

what occurs when these soaps are dispersed in water?

A

the hydrocarbon chains cluster together to form a sphere like structure called a micelle

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25
what is the arrangment within the micelle
the hydrohpobic chains cluster together away from the solvent in the centre while the hydrophyllic heads are on the surface.
26
why do micelles repel each other ?
due to the like charges they carry on the surface
27
how come they are good cleaning agents ?
because any dirt insoluble in water is soluble in the hydrocarbon phase that makes up the centre . therefore a stable emulsion is created of the water insoluble dirt partciles
28
what salts mainly make up domestic soaps ?
sodium salts
29
what salts mainly used in shaving creams and liquid soaps ?
potassium salts
30
what occurs if calcium and magnesium is present in the water ?
these ions exchange with the potassium and sodium ions and the resulting soaps are insoluble in water and therefore the new salts precipitate out as a grey scum
31
why is the calcium sterate insoluble ?
because it has a greater hydrophobic character so that a stable micelle cannot form
32
what is a detergent ?
this is a synthetic molecule that is similar to soaps but they don't form insoluble salts.
33
what are waxes ?
they are isolated from plants and animal material and are simple monoesters of long chain fatty acids and alcohols
34
what is the natural function of a wax ?
to form a waterproof coating for plants and insects
35
although waxes are solid why can they not form a crystalline ?
becuase the waxes are a mixture of different chain lengths.
36
whats the MP of waxes and what occurs as the chain length increases ?
they have a high MP , they become more brittle
37
what are membrane lipids very similar too and how do they differ?
triglycerides but one of the fatty acids is replaced with a different group , usually a phosphoric group.
38
what is the most common type of membrane lipid and where is it found ?
lecithin ( PC) , found in egg yolks
39
what is R1 typically ?
stearic acid , this is saturated ( single bond)
40
what is R2 typically ?
oleic acid , unsaturated ( double bonds)
41
what is lecithin also called ?
phosphatidylcholine ( PC)
42
what are cephalins or phosphatidylethanolamines ( PE) very similar too?
lecithins or PC
43
how are membrane lipids similar to fatty acid derived soaps and how is this useful?
they have a non polar tail and polar head which gives them excellent emulsifying properties
44
what is the major biological function of membrane lipids ?
to form a membrane bilayer
45
whats the function of the selectively permeable bilayer membrane?
It compartmentalises various materials it supports and provides a suitable environment for the action of enzymes etc provide sited for attachment of the cytoskeleton elements
46
how is the bilayer formed?
due to the packing of the non polar chains away from the aqueous phase
47
do cytoskeleton proteins attach to the inside or outside of the cell ?
inside
48
describe structure of glycerophospolipids and where found ?
the head has N present , whether its a N or NH3+ found in plasma memnbrane of many animal cells
49
where are glyceroclycolipids found ?
chloroplasts ,bacteria and blue green bacteria
50
describe structure of glyceroglycolipids ?
they have a ring as their polar head and phosphate ion
51
where are phosphingolipids found and describe structure?
found in plasma membrane of animal cells , has phosphate ion and N polar head
52
describe structure and where glycosphingolipids are found ?
it has ring structure as head and dominant in myelin , carry blood in erthyrocytes
53
describe the structure of cholestrol ?
it is a sterol , with 4 fused hydrocarbon rings and it has a hydrocarbon tail linked to one end and a hydroxyl group on the other end.
54
is cholesterol a fatty acid derivative?
nope it is a terpene
55
if cholesterol is present what occurs to the rigidity of the membrane ?
it becomes more rigid
56
whats the common features of all these molecules ?
their overall dimensions and twin hydrocarbon tails
57
is it just 2 lipid tails that can occur ?
nope you can get 4 tails
58
what allows the bilayer hydrophobic phase to be fluid rather than gelled ?
due to the hydrocarbon chain distortion that occurs due to cis double bonds , rings , branched etc
59
what occurs to the MP of lipids if 4 tails rather than 2 ?
the MP increases as more packing occurs
60
is the outside head and inside head of the bilayer need to be the same charge ?
no one can be positive and the other can be negative

CH112 (14 decks)

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