carbohydrates Flashcards

1
Q

name the 3 monosaccharides

A
  • glucose
  • fructose
  • galactose
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2
Q

name the 3 disaccharides and what they are composed of

A
  • maltose = glucose + glucose
  • lactose = glucose + galactose
  • sucrose = glucose + fructose
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3
Q

name the 3 polysaccharides

A
  • starch
  • cellulose
  • glycogen
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4
Q

what are the bonds between amino acids called?

A

peptide bonds

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5
Q

what is a hydrolysis reaction?

A

a reaction that breaks larger molecules into smaller ones using water molecules

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6
Q

what is a condensation reaction?

A

a reaction that joins molecules together with the release of water molecules

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7
Q

all monosaccharides are what type of sugars?

A

reducing sugars

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8
Q

what is the method for testing for reducing sugars?

A

1) Place the sample in a boiling tube (must be a liquid sample).
2) Add an equal volume of benedicts reagent (copper ii sulfate).
3) Heat the mixture in a boiling water bath for 5 minutes.
4) positive result= brick red precipitate is formed

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9
Q

what is the method for testing for non-reducing sugars?

A

1) (from doing the test for reducing sugars) the solution will remain blue, indicating a negative result.
2) add dilute HCl to the solution and boil.
3) add benedicts solution and the mixture should then give a positive result

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10
Q

what ratio do carbohydrates appear in?

A

Cx(H2O)y

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11
Q

what are the 2 pentose monosaccharides?

A
  • ribose = sugar in RNA molecules
  • deoxyribose = sugar in DNA molecules
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12
Q

what are the 2 polysaccharides that make up starch?

A

amylose and amylopectin

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13
Q

what are the structure and properties of amylose?

A
  • Alpha-glucose molecules joined by only 1,4 glycosidic bonds
  • bond angle means the chain twists and forms a helix which is stabilised by hydrogen bonding.
  • this makes amylose compact and not very soluble
  • not a branched structure
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14
Q

what are the structure and properties of amylopectin?

A
  • insoluble, branched, compact
  • alpha-glucose molecules mainly joined by 1,4 glycosidic bonds, but some 1,6 glycosidic bonds
  • this creates a slightly branched structure which forms a helix
  • can release glucose slightly quicker because it has more ends than amylose
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15
Q

what are the structure and properties of glycogen?

A
  • insoluble, branched, compact
  • 1,6 glycosidic bonds every 10 molecules
  • forms many branches and is very compact and ideal for storage
  • the free ends speed up the process of storing and releasing glucose molecules required in the cell (this is better for animals as we need more energy)
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16
Q

what are the structure and properties of cellulose?

A
  • made of beta-glucose molecules
  • they form a polymer by every other glucose molecule rotating 180 degrees
  • this means the OH groups on both the molecules are then close enough to form a 1,4 glycosidic bond
  • this does not coil or form any branches
17
Q

explain how cellulose molecules join together to form cellulose fibres

A
  • chains of beta glucose molecules are parallel and linked together by hydrogen bonds and form microfibrils
  • parallel microfibrils join together to form macrofibrils
  • macrofibrils combine to produce cellulose fibres.
18
Q

what are important properties of cellulose fibres?

A
  • strong and insoluble and used to make cell walls
  • this means it is hard to break down and forms the fibres necessary for a healthy digestive system
  • the wall is fully permeable
19
Q

what is the method for testing for reducing sugars?

A
  • use benedicts reagent (copper II sulfate)
    method
  • place the sample in a boiling tube (liquid form)
  • add an equal volume of benedicts reagent
  • heat the mixture in a water bath for 5 minutes
  • a brick red precipitate should form if a reducing sugar is present
20
Q

what is the method for testing non-reducing sugars?

A
  • (presuming a negative result for the reducing sugar test)
  • boil the solution with dilute HCl
  • add benedicts solution, this should then give a positive result

(in the case of sucrose or other molecules it is usually that they ar hydrolised into their reducing sugar monomers)