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A-level biology > Biological Molecules: Carbohydrates > Flashcards

Biological Molecules: Carbohydrates Flashcards

1
Q

what are some examples of reducing sugars

A

all monosaccharides and maltose

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2
Q

why are carbohydrates, proteins and lipids all organic compounds

A

they contain the elements Carbon and Hydrogen

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3
Q

why are carbon atoms key to the organic compounds

A
  • each carbon atom can form four covalent bonds which makes the compounds very stable (as covalent bonds are very strong and so require a large amount of energy to break them)
  • they can form covalent bonds with oxygen, nitrogen and sulfur
  • they can bond to form straight chains, branched chains or rings
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4
Q

what are macromolecules

A

very large molecules that contain 1000 or more atoms and therefore having a high molecular mass

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5
Q

difference between macromolecules and polymers

A

polymers can be macromolecules but not all macromolecules are polymers as the subunits of polymers have to be the same repeating units

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6
Q

what is the general formula for carbohydrates

A

Cx(H20)y

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7
Q

what are the three types of carbohydrates

A
  • monosaccharides, disaccharides and polysaccharides
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8
Q

definition of a monosaccharide

A
  • single sugar monomer
    (all are reducing sugars)
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9
Q

definition of a disaccharide

A

a sugar formed from two monosaccharides joined by a glycosidic bond

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10
Q

definition of a polysaccharide

A

a polymer formed by many monosaccharides joined by glycosidic bonds

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11
Q

what is maltose made up of

A

two alpha glucose molecules

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12
Q

what is sucrose made out of

A

an alpha glucose and a fructose molecule

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13
Q

what monomers is cellulose made out of

A

beta glucose

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14
Q

what monomers is starch made out of

A

alpha glucose in the form of amylose and amylopectin

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15
Q

what monomers is glycogen made out of

A

alpha glucose

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16
Q

how many carbons in a glyceraldehyde molecule

A

3

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17
Q

how many carbons in a ribose molecule

A

5

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18
Q

how many carbons in a glucose

A

6

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19
Q

are lipid molecules polymers

A

no because each fatty acid joins to a glycerol molecule rather than to each other

also separate molecules (such as triglycerides) are not held together by covalent bonds so they cannot be classed as polymers

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20
Q

what are the two types of covalent bonds

A

nonpolar - when the electrons are shared equally
or
polar - where the electrons are shared unequally due to an electronegative atom

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21
Q

what is a condensation reaction

A

when monomers combine together by covalent bonds accompanied by the release of a water molecule

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22
Q

how do you reverse a condensation reaction

A

using hydrolysis (add water and break the bonds)

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23
Q

what covalent bonds exist within carbohydrates ????

A

glycosidic bonds

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24
Q

what covalent bonds exist within lipids ?????

A

esters

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25
Q

what covalent bonds exist within nucleic acids ?????

A

phosphodiester

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26
Q

what is a reducing sugar

A

a sugar that can donate electrons (its carbonyl group becomes oxidised) -> the sugar becomes the reducing agent

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27
Q

why can reducing sugars be detected using Benedict’s solution

A

they reduce the soluble copper sulphate to insoluble (brick-red) copper oxide

28
Q

what are some examples of reducing sugars

A

all monosaccharides and maltose

29
Q

how are glucose, fructose and galactose linked

A

they all have the same molecular formula but have a different structural formula

the different arrangements of atoms in them gives them slightly different properties

30
Q

how can we adapt the Benedict’s solution to detect non-reducing sugars

A

they must first be hydrolysed (heat it with acid) to break the disaccharide into its two monosaccharides

31
Q

what is a triose

A

a monosaccharide formed from 3 carbon atoms

32
Q

structure of alpha glucose

A

H H

OH OH

33
Q

structure of beta glucose

A

H OH

OH H

34
Q

why are monosaccharides bonded together to form disaccharides and polysaccharides in cells

A
  • so they are more suitable for transport and storage
  • so they have less influence of a cell’s osmolarity
35
Q

how are di- and poly-saccharides formed

A

when two hydroxyl groups on different saccharides interact to form a strong covalent bonds call a glycosidic bond

36
Q

how are two alpha glucose molecules joined to form a disaccharide

A

the OH groups are affected on the ends: the OH of one is removed and the H from the OH of the other is removed

1st picture from 1.1.5 the glycosidic bond

37
Q

how do glycosidic bonds find the energy to form between saccharides

A

they are catalysed by enzymes specific to which OH groups are interacting

38
Q

what type of glycosidic bonds does maltose have

A
  • alpha 1,4
39
Q

what type of glycosidic bonds does sucrose have

A

alpha 1,2

40
Q

what type of glycosidic bonds does cellulose have

A

beta 1,4

41
Q

what type of glycosidic bond does amylose have

A

alpha 1,4

42
Q

what type of glycosidic bond does amylopectin have

A

alpha 1,4 and 1,6

43
Q

what are some examples of hydrolytic (hydrolysis) reactions

A
  • the digestion of food in the alimentary tract
  • the breakdown of stored carbohydrates in muscle and liver cells for use in cellular respiration
44
Q

what type of sugar is sucrose

A

non-reducing

45
Q

how do we prove sucrose is a non-reducing sugar

A
  • benedict’s test
  • negative result
  • heat with (hydrochloric) acid
  • benedict’s test
  • positive result
46
Q

why does a non-reducing sugar give a positive result after it has been heated in acid

A

the heating with acid provides the water that hydrolyses the glycosidic bond resulting in two monosaccharides which are reducing sugars

47
Q

what is a glycosidic bond

A

a strong covalent bond with an oxygen link that results from the interaction between two hydroxyl groups

48
Q

how do we make polysaccharides into monosaccharides

A

through MANY hydrolysis reactions

49
Q

what two phases do all chromatography techniques use

A
  • mobile phase
  • stationary phase
50
Q

1.1.6 chromatography: monosaccharides

A
51
Q

what chemical bond forms between monosaccharides

A

glycosidic bond

52
Q

how to calculate the chemical formula of a disaccharide using the formulas of two monosaccharides

A
  • add all the carbons, hydrogens and oxygens of both monomers then subtract 2H and 1O (the water molecule lost)
53
Q

what are three common disaccharides

A
  • maltose
  • sucrose
  • lactose
54
Q

what monosaccharides is maltose made out of

A

alpha glucose and alpha glucose

55
Q

what monosaccharides is sucrose made out of

A

alpha glucose and fructose

56
Q

what monosaccharides is lactose made out of

A

alpha glucose and galactose

57
Q

what are three common monosaccharides

A
  • glucose
  • galactose
  • fructose
58
Q

why are starch and glycogen good storage molecules

A
  • compact (so large quantities can be stored)
  • insoluble (so will have no osmotic effect)
59
Q

where and how is starch stored in plants

A

stored as granules in plastids

60
Q

what two polysaccharides is starch made out of and what percentage composition are they

A
  • amylose (10-30%)
  • amylopectin (70-90%)
61
Q

what is the structure of amylose

A
  • 1,4 glycosidic bonds between alpha glucose
  • which creates an unbranched molecule
62
Q

between starch and glycogen, which is quicker to be broken down and why

A

glycogen because it is more branched which means more enzymes can work on it simultaneously on the many terminal glucose molecules

62
Q

why does ‘being branched’ help a polymer be broken down quicker

A

it enables more free ends where glucose molecules can be removed [or added] (more enzymes can work simultaneously) allowing for hydrolysis [or condensation] reactions to occur more rapidly

62
Q

what is the structure of amylopectin

A
  • 1,4 and 1,6 glycosidic bonds between alpha glucose molecules
  • which creates a branched molecule
63
Q

what is glycogen the storage molecule for

A

animals and funghi

63
Q

why is it important that glycogen is more branched than starch

A
  • so it is able to be broken down quicker than starch because glycogen is used as a storage molecule in animals which have a higher metabolic rate than plants
    (whereas starch is used as a storage molecule in plants)
  • so it is more compact which helps animals store more
64
Q

where in animals has a high concentration of glycogen

A

in the liver and muscles as the cellular respiration rate is high in these cells

A-level biology (7 decks)

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