1. lipids and carbs fact test Flashcards

1
Q

what is a monomer

A

the smaller units from which larger molecules are made

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2
Q

what is a polymer

A

molecules made from a large number of monomers joined together

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3
Q

what are some examples of monomers

A

monosaccharides, amino acids and nuceotides

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4
Q

what are some examples of polymers

A

polysaccharides, proteins, polypeptides and DNA

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5
Q

what is a condensation reaction

A

joins 2 molecules together with the formation of a chemical bond and involves the elimination of a water molecule

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6
Q

what is a hydrolysis reaction

A

breaks a chemical bond between 2 molecules and involves the use of a water molecule

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7
Q

what are monosaccharides

A

monomers from which larger carbohydrates are made

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8
Q

what are some common monosaccharides

A

glucose, fructose and galactose

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9
Q

what does a condensation reaction between 2 monosaccharides form

A

a glycosidic bond

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10
Q

what are disaccharides

A

formed by the condensation between 2 monosaccharides

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11
Q

what monosaccharides make the disaccharide maltose

A

2 glucose molecules

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12
Q

what monosaccharides make the disaccharide sucrose

A

glucose and fructose

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13
Q

what monosaccharides make the disaccharide lactose

A

glucose and galactose

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14
Q

what are the 2 isomers of glucose called

A

alpha glucose
beta glucose

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15
Q

what are polysaccharides

A

formed by the condensation of many glucose units

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16
Q

what are the 4 polysaccharides

A

cellulose
starch - amylose
starch - amylopectin
glycogen

17
Q

what is cellulose like

A
  • found in plants
  • unbranched
  • made of beta glucose
  • bond between monomers is 1-4
  • provides strength
  • long, straight unbranched chains of beta glucose
    joined by hydrogen bonding to form microfibrils which provides strength
18
Q

what is starch (amylose) like

A
  • found in plants
  • unbranched
  • made of alpha glucose
  • bond between monomers is 1-4
  • stores energy
19
Q

what is starch (amylopectin) like

A
  • found in plants
  • branched
  • made of alpha glucose
  • bonds between monomers are -4 and 1-6
    stores energy
  • branched therefore more ends for faster hydrolysis
20
Q

what is glycogen like

A
  • found in animals
  • branched
  • made of alpha glucose
  • bonds between monomers is 1-4 and 1-6
  • stores energy
  • branched therefore more ends for faster hydrolysis
21
Q

what do amylose, amylopectin and glycogen have in common

A
  • polymer of alpha glucose so easily hydrolysed to provide glucose for respiration
  • has coils therefore compact
  • made of glucose so provides respiratory substrate for energy release
  • insoluble so doesn’t affect water potential/osmosis
  • large molecule so can’t cross the cell membrane
22
Q

what is the test for starch

A
  • grind/crush food sample
  • add iodine in potassium iodide solution
  • positive result is colour change from orange/brown to blue/black
23
Q

what are reducing sugars

A

a reducing sugar is a sugar that can donate electrons (i.e. reduce) another chemical e.g benedict’s reagent

24
Q

what are some examples of reducing sugars

A

all monosaccharides and some disaccharides e.g maltose

25
how do you test for reducing sugars
- add benedict's solution and heat in a hot water bath - positive result is colour change from blue to brick red
26
what are non-reducing sugars
don't change colour when heated with benedict's solution
27
how do you detect non-reducing sugars
sample must first be hydrolysed into it's constituent monosaccharides
28
what are some examples of non-reducing sugars
some disaccharides e.g sucrose
29
what is the test for non-reducing sugars
- first confirm no reducing sugars are present - get a fresh sample boil in acid (e.g hydrochloric) which will hydrolyse any dissacharide present into its constituent monosaccharides - neutralise (e.g sodium hydrogen carbonate) as benedict's reagent will not work in acidic conditions - add benedict's reagent and heat in a hot water bath - observe colour change
30
what are lipids
- not polymers as they aren't made up of repeating units - made up of carbon, hydrogen and oxygen - insoluble in water, soluble in alcohols
31
what are the roles of lipids
- cell membranes - energy source - water proofing - insulation - protection
32
how do you carry out the emulsion test (test for lipids)
- add ethanol to substance - add water - positive result is milky white emulsion - negative result is colourless
33
what are triglycerides
1 glycerol molecule bonded to 3 fatty acid chains 3 water molecules are eliminated to make a triglyceride
34
what is an ester bond
covalent bond between glycerol and fatty acid formed by condensation reaction and broken by hydrolysis reaction
35
where is the ester bond always formed
the side with the COOH group
36
what are saturated fatty acids
all C-C single bonds carbons are fully saturated with hydrogen atoms tend to form fats solid at room temperature
37
what are unsaturated fatty acids
can be monounsaturated - only one C=C double bond can be polyunsaturated - many C=C double bonds tend to form oils and are liquid at room temperature
38
what are phospholipids
1 glycerol bonded to 2 fatty acids and one phosphate group
39
what does amphiphilic mean
a molecule having both hydrophobic (non-polar) and hydrophilic (polar) regions e.g. phospholipids