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Biology A Level > Biological Molecules :). > Flashcards

Biological Molecules :). Flashcards

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1
Q

Name some important functions of water?

A 
Reactant 
Solvent
Transports substances 
Helps with temperature control
Habitat
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2
Q

How is water being a reactant useful?

A

It’s in lots of important chemical reactants including hydrolysis reactions

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3
Q

What’s a solvent?

A

Something with substances dissolved in it

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4
Q

Where do mort biological reactions take place?

A

In solution (e.g. Cytoplasm of eukaryotes and prokaryotic cells) so water essential

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5
Q

What causes water be able to transport substances?

A

It’s liquid and a solvent so materials like glucose and oxygen can be be dissolved and carried around plants and animals

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6
Q

Why does water help with temperate control?

A

It has a specific heat capacity and a high latent heat of evaporation

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7
Q

How come water can be a habitat?

A

Helps with temperature control
Solvent
Becomes less dense when freezes so many many organisms can survive and reproduce in it

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8
Q

Molecule of water?

A

One oxygen (O) joined to two atoms of hydrogen (H2) shared by electrons

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9
Q

Why is the other side of each hydrogen atom left with a slight positive charge?

A

Shared negative hydrogen electrons pulled towards oxygen atom so other side of hydrogen left slightly positive

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10
Q

What does the unpaired negative electrons in oxygen give it?

A

A slightly negative charge

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11
Q

Why is water polar?

A

Has partial negative charge on one side and a partial positive charge on the other.

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12
Q

What do slightly-negatively charged oxygen do to the slightly positively-charged hydrogen atoms of the other water molecules?

A

Attract them

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13
Q

What’s the attraction called?

A

Hydrogen bonding and gives water some of its useful properties

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14
Q

What’s specific heat capacity?

A

The energy needed to raise the temperature of 1g of a substance by 1oC

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15
Q

Why does water have a high heat capacity?

A

Hydrogen bonds between water molecules absorb a lot of energy so water has a high specific heat capacity so takes s lot of energy to heat up

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16
Q

Why is water a good habitat?

A

Doesn’t experience rapid temperature changes

Temperate under water likely to be more stable than on land

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17
Q

How much energy to break a hydrogen bond between water molecules?

A

Lots

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18
Q

Lot of energy used up when water evaporates water property?

A

High latent heat of evaporation

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19
Q

Why do mammals sweat when hot ?

A

Waters great at cooling things

Cools surface of the skin

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20
Q

What is cohesion?

A

Attraction between molecules of same type

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21
Q

Why are water molecules very cohesive?

A

Polar

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22
Q

What’s does the cohesive of water help?

A

Water to flow making great for transporting substances. Helps water transported up plant stems in transpiration stream

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23
Q

What are a lot of important substances in biological reactions?

A

Ionic

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24
Q

What’s ionic?

A

Made from positively charged atoms or molecules and one negatively-charged atom or molecule

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25
Q

Salt is made from?

A

A positive sodium ion and a negative chloride ion

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26
Q

What happens because water is polar?

A

Slightly positive end of water molecule will be attracted to the negative ion and the slightly negative end of water molecule will be attracted to the positive ion they will dissolve

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27
Q

What makes water useful as a solvent in living organisms?

A

It’s polarity

E.g. Humans important ions can dissolve in water in blood and be transported around the body

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28
Q

What happens to water at low temperature?

A

Freezes turns from liquid to solid

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29
Q

How far are water molecules held in ice compared to liquid water?

A

Further

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30
Q

Why does ice float?

A

water molecules form four hydrogen bonds up other water molecules making a lattice shape making ice less dense than liquid water

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31
Q

Why is water less dense than solid useful to living organisms?

A

In cold temperatures ice forms insulating layer on top of water- the water doesn’t freeze so organism that live in water don’t freeze and can still move around

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32
Q

What are most carbohydrates?

A

Polymers

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33
Q

Polymers are?

A

Molecule made up of monomers bonded together

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34
Q

Monomers make up what?

A

Carbohydrates called monosaccharides

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35
Q

What is glucose?

A

A six carbon monosaccharides meaning hexose monosaccharide

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36
Q

Two type of glucose are?

A

Alpha and beta

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37
Q

What is glucose structure related to?

A

It’s function as the main energy source in animals and plants

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38
Q

What’s does glucose structure make it?

A

Soluble
Easily transported
Chemical bonds contain lots of energy

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39
Q

What is ribose?

A

A monosaccharide with five carbon atoms

Pentose monosaccharide

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40
Q

What are carbohydrates made of?

A

Carbon
Hydrogen
Oxygen

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41
Q

For every carbon atom in carbohydrate usually how many oxygen and hydrogen are there usually?

A

2 Hydrogen

1 Oxygen

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42
Q

How are monosaccharides joined together?

A

By glucosidic bonds

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43
Q

What’s a condensation reaction?

A

During synthesis, hydrogen atom on one monosaccharide binds to a hydroxyl group on the other releasing a molecule of water

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44
Q

What’s hydrolysis?

A

Reverse of condensation

Water molecule reacts with glycosidic bond breaking it apart

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45
Q

What happens when two monosaccharides join together?

A

Disaccharide

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46
Q

Alpha glucose + alpha glucose ->

A

Maltose

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47
Q

Maltose

A

Alpha glucose + alpha glucose ->

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48
Q

How other disaccharides made?

A

In a similar way

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49
Q

Sucrose->

A

Alpha glucose + fructose

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50
Q

Alpha glucose + fructose

A

Sucrose->

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51
Q

Lactose

A

Beta glucose+ galactose->

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52
Q

Beta glucose+ galactose->

A

Lactose

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53
Q

Polysaccharide is?

A

When more than two monosaccharides are joined together

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54
Q

What makes amylose

A

Lots of alpha molecules joined together by glycosidic

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55
Q

Three polysaccharides you need to know about?

A

Starch
Glucogen
Cellulose

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56
Q

Where do cells get their energy from?

A

Glucose

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57
Q

How do plants store excess glucose as?

A

Starch

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58
Q

When a plant needs more glucose for energy?

A

It breaks down starch to release the glucose

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59
Q

What is starch a mix of?

A

Two polysaccharides of alpha-glucose amylose and amylopectin

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60
Q

Describe amylose?

A

Long in branched chain of alpha glucose
Angles of glucosidic bond give it coiled structure like cylinder
Compact
Good for storage

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61
Q

Why is amylose good for storage?

A

You can fit more into a small space

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62
Q

Describe amylopectin

A

Long branched chain of alpha glucose
Side branches allow enzymes to break down molecules to get glucosidic bonds easily meaning glucose gets released quickly

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63
Q

Is starch soluble or insoluble?

A

Insoluble in water so didn’t cause water to enter cells by osmosis which would make then swell
Good for storage

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64
Q

Animals cells get energy from?

A

Glucose

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65
Q

How do animals store excess glucose?

A

As glycogen

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66
Q

Glycogen is?

A

Another polysaccharide of alpha-glucose

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67
Q

Structure of glycogen

A

Similar to amylopectin except lots more side branches coming off it
Loads of side branches mean stored glucose can be released quicker which is important for energy release
Compact

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68
Q

Cellulose is made of?

A

Long, in branched chains of beta glucose

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69
Q

What happens when beta-glucose molecules bond?

A

They form straight cellulose chains

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70
Q

How are cellulose chains linked together?

A

By hydrogen bonds to form strong fibres called microfibrils

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71
Q

What do strong fibres means for cellulose?

A

Provide structural support for cells

E.g. In plant cell walls

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72
Q

How much water in a cell?

A

About 80%

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73
Q

What are triglycerides?

A

Macromolecules

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74
Q

What are macromolecules ?

A

Complex molecules with relatively large molecular mass

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75
Q

What do all lipids contain including triglycerides ?

A

Carbon
Hydrogen
Oxygen

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76
Q

Basic structure of triglyceride?

A

One molecule of glycerol with three fatty acids attached to it

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77
Q

What do fatty acid molecules have?

A

Long tails made of hydrocarbons

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78
Q

What is a hydrocarbon?

A

A compound of atoms containing only carbon and hydrogen atoms

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79
Q

What are these fatty acid tails?

A

Hydrophobic

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80
Q

What do these tails make lipids?

A

Insoluble in water

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81
Q

What do all fatty acids have the same and what varies?

A

Same basic structure

Hydrocarbon tails varies

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82
Q

What are triglycerides synthesised?

A

By formation of water bond between each fatty acid and glycerol molecule

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83
Q

How is each ester bind of triglycerides formed?

A

Condensation reaction

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84
Q

Process in which triglycerides formed?

A

Esterification

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85
Q

When do triglycerides break down?

A

When esters bonds are broken. Each ester bond broken in hydrolysis reaction

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86
Q

Two types of fatty acids?

A

Saturated

Unsaturated

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87
Q

Difference between saturated and unsaturated fatty acids?

A

Hydrocarbon tails

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88
Q

Saturated fatty acids bonds?

A

Don’t have double bonds between carbon atoms. Fatty acid saturated with hydrogen

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89
Q

Unsaturated fatty acids bonds?

A

At least one double bond between carbon atoms causing chain to kink

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90
Q

General formula for fatty acid is?

A

CnH(2n+1)COOH

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91
Q

What are phospholipids?

A

Macromolecules

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92
Q

What are phospholipids like?

A

Similar to triglycerides except one of fatty acid molecules replaced by phosphate group

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93
Q

Phosphate group and fatty acid tail (phospholipids)?

A

Phosphate group is hydrophilic

Fatty acid hydrophobic

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94
Q

What are triglycerides used for plant and animals?

A

Mainly Energy store molecule

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95
Q

What do some bacteria use triglycerides for?

A

To store both both energy and carbon (mycobacterium tuberculosis does it)

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96
Q

Two reasons why triglycerides are good for storage?

A

Insoluble

Long hydrocarbon tails of fatty acid contain lots of chemical energy

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97
Q

Long hydrocarbon tails of fatty acid contain lots of chemical energy explain?

A

Load of energy released when broken down because of tails lipids contain twice as much energy per gram as carbohydrate

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98
Q

Explain insoluble for good storage triglyceride?

A

Don’t cause water to enter cells by osmosis which would make them swell.

99
Q

Triglycerides bundle together as insoluble droplets in cells because?

A

Fatty acid tails are hydrophobic

Tails face onwards shielding themselves from water with glycerol heads

100
Q

Where are phospholipids found?

A

Cell membrane of all eukaryotes and prokaryotes

101
Q

Phospholipids make up?

A

Phospholipid bilayer

102
Q

Cell membrane control what?

A

Enters and leaves a cell

103
Q

Phospholipids heads are?

A

Hydrophilic

104
Q

Phospholipid tails are?

A

Hydrophobic

105
Q

Phospholipid bilayer?

A

Form double layer with heads facing outwards towards water on either side

106
Q

Centre of bilayer is hydrophobic so?

A

Water-soluble substances can’t easily pass through

Membranes act as barrier to those substances

107
Q

Cholesterol is?

A

Another type of lipid

108
Q

Cholesterol structure

A

Hydrocarbon ring structure attached to hydrocarbon tail. Ring structure has polar hydroxyl group attached to fit in between phospholipid molecules in membrane

109
Q

Cholesterol size and shape?

A

Small
Flattened shape
Allows cholesterol to fit between phospholipid molecules in membrane

110
Q

What to cholesterol bind to?

A

Hydrophobic tails of phospholipids causing them to pack closer together helping membrane less fluid and more rigid

111
Q

Proteins are?

A

Polymers

112
Q

Amino acids are?

A

Monomers

113
Q

Dipeptide is?

A

Two amino acids joining together

114
Q

Polypeptide is?

A

More than 2 amino acids join together

115
Q

Proteins made of?

A

One of more polypeptides

116
Q

Amino acids have the same?

A

General structure

117
Q

General structure amino acid

A

Carboxyl group and amino group attached to carbon atom

118
Q

Difference between amino acids is?

A

Variable group they contain

119
Q

All amino acids contain?

A

Carbon
Hydrogen
Nitrogen

120
Q

What do some amino acids contain?

A

Sulphur

121
Q

How are amino acids linked together?

A

By peptide bonds to form dipeptides and polypeptides in condensation reaction

122
Q

Reverse reaction does what?

A

Adds molecules of water to break peptide bond hydrolysis reaction

123
Q

Proteins levels?

A

Primary
Secondary
Tertiary
Quaternary

124
Q

Primary structure

A

Sequence of amino acids in polypeptide chain
Different proteins have different sequences of amino acids in primary structure. Change in one amino acid may change whole protein structure.

125
Q

Secondary structure

A

Polypeptide chain doesn’t stay flat or straight

Hydrogen bonds form nearby amino acids in chain makes alpha helix or beta pleated sheet

126
Q

Tertiary structure

A

Coiled or folded chain of Amino acids coiled and foiled further
More bonds between different parts of polypeptide chain.

127
Q

Tertiary structure is last for what proteins?

A

Ones made from single polypeptide chain

128
Q

Quaternary structure

A

Several different polypeptide chains held by bond. Way in which there are held together

129
Q

Haemoglobin quaternary structure?

A

Made of four polypeptide chains bonded together

130
Q

Proteins made from what is quaternary the final 3D structure?

A

Proteins made from more than one polypeptide chain

131
Q

Computer modelling can create?

A

:3D interactive images of proteins

Handy for investigating different levels of structure in protein molecules

132
Q

Primary structure bonds?

A

Peptide bonds

133
Q

Secondary structure bonds?

A

Hydrogen bonds

134
Q

Tertiary structure bonds?

A

Ionic
Disulfide bonds
Hydrophobic and hydrophilic interactions
Hydrogen atoms

135
Q

Ionic bonds in tertiary?

A

Attraction between negatively-charged R groups and positively-charged R groups on different parts of the molecule

136
Q

Disulfide bonds tertiary?

A

Whenever two molecules of amino acids cysteine come close together, the sulfur atom in one cysteine bond to sulfur in other cysteine forming disulfate bond

137
Q

Hydrophobic and hydrophilic interactions tertiary?

A

When hydrophobic R groups are close in protein tend to clump together.
Means hydrophilic R group more likely to be pushed to outside affects how protein folds up in final structure

138
Q

Hydrogen bond tertiary structure?

A

Weak bonds form slightly positively-charged hydrogen atoms in some R groups and slightly negatively-charged atoms in other R group on polypeptide chain

139
Q

Quaternary structure bonds?

A

Determined by tertiary structure of individual polypeptide chains being bonded together. Can be influenced by all tertiary bonds

140
Q

Gobular shape?

A

Round and compact

141
Q

Hydrophilic R groups on amino acids tend to be pushed outside of the molecule on gobular protein why?

A

Hydrophobic and hydrophilic interactions in proteins tertiary structure

142
Q

Gobular proteins insoluble or soluble?

A

Soluble so easily transported in fluids

143
Q

Name three functions of gobular proteins in living organisms?

A

Haemoglobin
Insulin
Amylase

144
Q

Haemoglobin function

A

Carries blood around body in red blood cell

145
Q

Haemoglobin cool stuff

A

Known as conjugated protein as protein with prosthetic group
Each of four polypeptide chains in haemoglobin has prosthetic group (haem). Haem group contains iron which oxygen binds to.

146
Q

Insulin is?

A

Hormone secreted by pancreas

147
Q

Insulin function

A

Helps regulate blood glucose level

148
Q

Why is insulin’s solubility important?

A

Can be transported in blood to tissues where insulin molecule consists of 2 polypeptide chains held together by disulfide bonds

149
Q

Amylase is?

A

Enzyme that catalyses breakdown of starch in digestive system

150
Q

Amylase structure?

A

Made of single chain of amino acids

Secondary structure both alpha-helix and beta-pleated sheets section.

151
Q

What are most enzymes?

A

Gobular

152
Q

Fibrous proteins are?

A

Insoluble and strong
Structural protein
Unreactive

153
Q

Name 3 fibrous proteins?

A

Collagen
Keratin
Elastin

154
Q

Collagen found where?

A

Found in animal connective tissues like bones, skin and muscle

155
Q

Collagen describe

A

Strong molecule

Minerals can bind to protein to increase rigidity in bone

156
Q

Keratin found

A

External structures of animals

Skin, hair, nails, feathers and horns

157
Q

Keratin describe

A

Either flexible or hard and tough

158
Q

Elastin found

A

Elastic connective tissue

Skin, large mood vessels and some ligaments

159
Q

Elastin describe

A

Elastic so allows tissue to return to original shape after stretched

160
Q

Ion is

A

Atom that has electric charge

161
Q

Cation

A

Positive charge ion

162
Q

Anion

A

Negative charge ion

163
Q

Inorganic ion doesn’t contain

A

Carbon

164
Q

Inorganic ions really important in

A

Biological processes

165
Q

Calcium symbol

A

Ca2+

166
Q

Calcium function 4

A

Transmission of nerve impulses
Release of insulin from pancreas
Cofactor for many enzymes
Bone formation

167
Q

Sodium symbol

A

Na+

168
Q

Sodium function

A

Generate nerve impulses for muscle contraction and regulating fluid balance in body

169
Q

Potassium symbol

A

K+

170
Q

Potassium function

A

Generate nerve impulse for muscle contractions and regulating fluid balance in body
Activated essential enzymes needed for photosynthesis in plant cells

171
Q

Hydrogen symbol

A

H+

172
Q

Hydrogen function

A

Affects pH of substances

Important for photosynthesis in thylakoid membranes in chloroplasts

173
Q

Ammonium symbol

A

NH+

174
Q

Ammonium functions

A

Absorbed by soil by plants

Important source of nitrogen

175
Q

Nitrate

A

NO3 -

176
Q

Nitrate function

A

Absorbed from soil by plants

Important source of nitrogen

177
Q

Hydrogencarbonate symbol

A

HCO3 -

178
Q

Hydrogencarbonate function

A

Acts as buffer helps maintain pH of blood

179
Q

Chloride symbol

A

Cl-

180
Q

Chloride function

A

Involved in chloride shift helping to maintain pH of blood during gas exchange
Acts as cofactor for amylase
Involved in some nerve impulses

181
Q

Phosphate symbol

A

PO4 3-

182
Q

Phosphate function

A

Involved in photosynthesis and respiration

Needed for synthesis of many biology molecules

183
Q

Hydroxide function

A

Affects pH of substance

184
Q

OH-

A

Hydroxide

185
Q

What is sugar the general term for?

A

Monosaccharides and disaccharides

186
Q

Two categories of sugar?

A

Reducing or non-reducing

187
Q

The Benedict’s test for what?

A

Sugars it differs depending on type of sugar you are testing for

188
Q

What do reducing sugar include?

A

All monosaccharides (glucose…) and some disaccharides (maltose, lactose…)

189
Q

Steps of reducing sugar Benedict’s?

A

Add Benedict’s reagent (blue) to sample and heat in water bath that’s been brought to boil. If tests positive coloured precipitate will form.

190
Q

Reducing sugars concentration Benedict’s?

A

The higher the concentration the further the colour change goes
You can compare amounts of reducing sugar in different solutions. More accurate version is to filter solution and weigh out precipitate

191
Q

If Benedict’s reducing sugars test fails?

A

If reducing sugars test is negative there could still be non-reducing sugars present

192
Q

How to test for non-reducing sugars?

A

Break them down into monosaccharides
Get new sample add dilute HCL, careful heat in water bath, then neutralise with sodium hydrogencarbonate
Do Benedict’s test

193
Q

What happens if tests for reducing or non-reducing test is positive?

A

Form coloured precipitate (brick red)

If stays blue doesn’t contain any sugar

194
Q

Test for glucose

A

Using test strips coated in reagent
Strips dipped in test solution if colour change glucose present
Colour change compared to chart to give indication of concentration of glucose present.

195
Q

Test for glucose use?

A

Testing persons urine for glucose to test for diabetes

196
Q

Starch test

A

Iodine test

Add iodine dissolved in potassium iodide solution to test sample

197
Q

If starch present

A

Sample changes from browny-orange to dark blue-black colour

198
Q

If no starch

A

Stays browny-orange

199
Q

Protein test

A

Biuret test
Test solution needs to alkaline so add few drops of sodium hydroxide solution
Add copper II sulfate solution

200
Q

Protein present

A

Solution turns purple

201
Q

No protein present

A

Stay blue

202
Q

Lipid test

A

Emulsion test

Shake test substance with ethanol for about a minute then pour solution into water

203
Q

Lipid present

A

Turn milky

More noticeable if there is more

204
Q

No lipid

A

Solution stay clear

205
Q

Colorimeter used for?

A

Determine concentration of glucose solution

206
Q

colorimeter 1

A

Use Benedict’s reagent and colorimeter to get quanta tube estimate of how much glucose (other reducing sugar) is in solution

207
Q

Colorimetry is

A

Device that measures strength of coloured solution of how much light passes through it

208
Q

What does colorimetry measure?

A

Absorbance. The more concentrated the colour of the solution the higher the absorbance is.

209
Q

How is it easiest to measure the reducing sugar levels?

A

Measure concentration of blue Benedict’s solution that’s left after test (the paper the solution the more glucose there was) higher glucose concentration the lower the absorbance of the solution

210
Q

Initial step of using colorimetry for glucose solution?

A

Make up several glucose solutions of different known concentration
Can do this using serial dilution technique

211
Q

How do you make 5 serial dilutions with dilution factor of 2 starting with initial glucose concentration of 40mM?
Step 1

A

Line up 5 test tubes in a rack

212
Q

How do you make 5 serial dilutions with dilution factor of 2 starting with initial glucose concentration of 40mM?
Step 2

A

Add 10cm3 of initial 40mM of solution glucose solution to first test tube and 5cm3 of distilled water to other four test tubes

213
Q

How do you make 5 serial dilutions with dilution factor of 2 starting with initial glucose concentration of 40mM?
Step 3

A

Using pipette draw 5cm3 of solution from first test tube add distilled water in second test tube and mix solution throughly. You now have 10cm3 of solution half as concentrated as solution that’s half as concentrated as solution (20mM)

214
Q

How do you make 5 serial dilutions with dilution factor of 2 starting with initial glucose concentration of 40mM?
Step 4

A

Repeat process three more times to create solutions of 10mM, 5mM, 2.5mM

215
Q

What do you need to make the calibration curve?

A

Glucose solutions

216
Q

How do you make a calibration curve?

Step 1

A

Do Benedict’s test on each solution plus negative control of pure water. Use same amount of Benedict’s in each case

217
Q

How do you make a calibration curve?

Step 2

A

Remove any precipitate either leave for 24 hours so precipitate settles out or centrifuge them

218
Q

How do you make a calibration curve?

Step 3

A

Use colorimeter (with red filter) to measure absorbance of Benedict’s solution remaining in each tube

219
Q

How do you make a calibration curve?

Step 4

A

Use results to make calibration curve showing absorbance against glucose concentration

220
Q

What can you do with this calibration curve?

A

Test Unknown solution in same way as known concentrations and use calibration curve to find its concentration

221
Q

What’s a biosensor?

A

A device that uses biological molecules such as an enzymes to detect a chemical

222
Q

How does a biosensor work?

A

Biological molecule produced signal which is converted to electrical signal by transducer (part of biosensor). Electrical signal processed and use to work out other information

223
Q

Example of biosensor?

A

Glucose biosensors

224
Q

What is a glucose biosensor used for?

A

To determine the concentration of glucose in a solution

225
Q

How does a glucose biosensor work?

A

By using enzyme glucose oxidase and electrodes. The enzyme catalyses oxidation of glucose at electrodes creating charge which is converted to electrical signal by electrodes (transducer). Electrical signal processed to electrical out initial glucose concentration

226
Q

What is chromatography used for?

A

To separate stuff in mixture once separated can often identify components

227
Q

Give an example of use of chromatography?

A

Used to separate and identify biological molecules e.g. Amino acids, carbohydrates, vitamins and nucleic acids

228
Q

Two types of chromatography you need to know about?

A

Paper and thin-layer chromatography

229
Q

Two phases in basic set up of chromatography?

A

Mobile and stationary

230
Q

Mobile phase

A

Where molecules can move

In paper and thin-later chromatography mobile phase is liquid solvent e.g. Ethanol or water

231
Q

Stationary phase

A

Where molecules can’t move
Paper chromatography stationary phase is chromatography paper
Thin-layer chromatography stationary phase is thin layer of solid e.g. Silica gel on a glass or plastic plate

232
Q

Basic principles of chromatography

A

Mobile phase moves through or over stationary phase
Components in mixture spend different amounts of time in mobile and stationary phase
Components spend longer in mobile phase travel faster or further
Time spend in different phases is what separates components of mixture

233
Q

Paper chromatography step 1

A

Draw pencil line near bottom of chromatography paper and put concentrated spot of mixture of amino acids in it. Best if carefully roll paper into cylinder with spot on outside so stand up.

234
Q

Paper chromatography step 2

A

Add small amount of prepared solvent to beaker and dip the bottom of paper into it not the spot. Should be done in fume cupboard. Cover lid to stop solvent evaporating

235
Q

Prepared solvent paper chromatography will be?

A

Mixture of butan-1-ol, glacial ethanoic acid and water used for amino acids

236
Q

Paper chromatography step 3

A

As solvent spreads up paper, different amino acids move with it at different rates so separate out.

237
Q

Paper chromatography step 4

A

When solvent nearly reached top take paper out and Mark solvent front with pencil. Then leave paper to dry out before you analyse it.

238
Q

Paper chromatography step 5

A

Amino acids aren’t coloured meaning you won’t be able to see them on paper. Before you can analyse them you have to spray paper with ninhydrin solution to turn amino acids purple. Should be done in fume cupboard and gloves should be worn.

239
Q

Paper chromatography step 6

A

Use Rf value to identify separated molecules

240
Q

What is Rf value?

A

Rate of distance travelled by spot to distance travelled by solvent

241
Q

How to calculate Rf value?

A

Rf of amino acid= (distance traveled by spot)/ (distance travelled by solvent).

242
Q

What do measure once you have measured how far the spot has travelled?

A

Measure from point of origin to vertical centre of the spot

243
Q

How do you use the Rf values once calculated?

A

Looking them up in database or table of known values

Biology A Level (26 decks)

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