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Biological Molecules Flashcards

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1
Q

What is a condensation reaction

A

Reactions that occur when two molecules are joined together with the removal of water

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2
Q

What is a hydrolysis reaction

A

Reactions that occur when a molecule is split into two smaller sections / molecules with the addition of water

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3
Q

Joining molecules =

Breaking molecules =

A

condensation

hydrolysis

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4
Q

What is a monomer

A

A small molecule which binds to many other identical molecules to form a polymer

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5
Q

What is a polymer

A

A large molecule made from many smaller molecules called monomers

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6
Q

The carbohydrates are made up of

A

Monosaccharides
Disaccharides
Polysaccharides

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7
Q

What are the properties of monosaccharides

A
  • sugars , which taste sweet
  • soluble in water
  • insoluble in non polar solvents
  • large number of carbon hydrogen bonds
  • have a backbone of a single bonded carbon atoms
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8
Q

What is an isomer

A

Molecules with the same formula but whose atoms are arranged differently

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9
Q

Describe alpha glucose

A

6 carbon sugar
Hexose
-Has H on top of the carbon 1 and OH below
Covalent bonds

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10
Q

Describe beta glucose

A
  • 6 carbon sugar
  • hexose
  • HO group ontop of the carbon 1
  • covalent bonds
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11
Q

Describe ribose

A

5 carbon sugar

Pentose

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12
Q

What are the properties of disaccharides

A

Sweet

Soluble

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13
Q

How do disaccharides form

A

When condensation reactions occur

Two monosaccharides join together , form a glycosidic bond

Two hydroxyl groups line up next to each other , from which a water molecule is released

Leaves oxygen atom acting as a link between the two monosaccharides

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14
Q

How disaccharides are broken

A

Broken into two monosaccharides by hydrolysis reactions , which requires addition of water . The water provides a hydroxyl group and a hydrogen group

Breaks glycosidic bond to break

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15
Q

What are the different disaccharides and what are they made off

A

Alpha glucose + Alpha glucose = maltose

Alpha glucose +fructose = sucrose

Beta glucose + alpha glucose = lactose

Beta glucose + beta glucose = cellobiose

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16
Q

How do polysaccharides form

A

In a series of condensation reactions . Each time a glycosidic bond forms water will be given off

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17
Q

Name to two types of starch

A

Amylose

Amylopectin

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18
Q

Describe amylose structure

A

Made from a long chain of alpha glucose molecules , it has glycosidic binds between carbon 1 and 4

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19
Q

Amylose coils into a spiral shape with

A

Hydrogen bonds holding the spiral in place . Hydroxyl groups on a carbon 2 are situated on the inside of the coil making the molecule less soluble and allowing the hydrogen bound to form to maintain the coils structure

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20
Q

Describe amylopectin structure

A

Made of chains of alpha glucose

Has glycosidic bonds between carbon 1 and 4 but in addition it has branches formed by glycosidic bonds between 1 and 4

It also coils into a spiral shape held together with hydrogen bonds but with branches emerging from the spiral

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21
Q

What are the functions of starch

A

Used as an energy store, for when glucose is needed for respiration

It’s less soluble in water so doesn’t affect osmosis

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22
Q

How is the structure of polysaccharides important for its fiction

A

Glycogen and starch are compact , which means they do not occupy a large amount of space , so they can have more glycogen and starch molecules

Polysaccharides hold glucose molecules in chains so they can be easily shipped off from the end of the chain by hydrolysis when required for respiration , it doesn’t interfere with osmosis

Branches even more compact , easier to snip off

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23
Q

Amylose is responsible for hydrolysisng ?

Glucosidase is responsible for hydrolysisng ?

A

1-4 glycosidic linkages

1-6 glycosidic linkages

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24
Q

Where is glycogen found

A

Animal cells

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25
Q

Describe glycogen structure

A

Glycosidic bonds between carbon 1 and 4 and branches formed by glycosidic bonds between carbon 1 and 6- with Alpha glucose

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26
Q

What’s the function of glycogen

A

It’s an energy store do when glucose needs it for respiration

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27
Q

How is the structure of glycogen important for its function

A

It’s more compact with more branches so it allowed more molecules to be snipped off . This is because it needs more access to these molecules as animals are more metabolically active

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28
Q

Properties of cellulose

A

Tough
Insoluble
Fibrous substances

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29
Q

What’s the structure of cellulose

A

Are straight and lie side by side , made of beta glucose
Hydroxyl groups on carbon 1 are inverted , this means every other beta glucose molecule in the chain is rotate 180 degrees

Hydrogen bonding between the rotated beta glucose in each chain also give the chain additional strength and stops it spiralling

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30
Q

Beta glucose turns into several hundred chains then turns into

A

Microfibrils

Macrofibils

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31
Q

What the key features help the plant cell to do its job

A

Because plants do not have a rigid skeleton. Each cell needs to have strength to support the whole plant

There is space between macrofibrils for water and minerals ions to pass on their way into and out of the cells. . This makes cells walls permeable

Highly tensile strength which prevents cells from bursting when they are turgid again helping to support the whole plant . Turgid cells also press against each other supporting the structures of the plant as a whole . The wall protects delicate cell membranes

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32
Q

Describe the triglycerides structure

A

Made up of 1 glycerol and 3 fatty acid tails

Condensation reaction , 3 lots of water given off

Ester bonds formed

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33
Q

Describe lipids

A

Contain large amounts of carbon and hydrogen and smaller amounts of oxygen . They are insoluble in water because they are not polar and do not attract water molecules , but dissolve in alcohol

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34
Q

What are the 3 most important lipids

A

Triglyceride
Phospholipids
Steroids

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35
Q

Describe saturated fatty acids

A

If a fatty acid is saturated , this means that there are no c=c bonds in a molecule . They only have single bonds

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36
Q

Describe unsaturated fatty acids

A

There is a double bind between two of the carbon atoms instead which means that fewer hydrogen atoms can be bonded to the molecule

Having one or more c=c bonds change the shape of the hydrocarbon chain , giving a kink

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37
Q

What are the function of triglycerides

A

Energy source - they can be broken in respiration to release energy and generate ATP

Energy store - because they’re insoluble in water they can be stored so they don’t effect water potential

Insulation -adipose tissue is a storage location for lipids in whales , acting as a heat insulated .

Buoyancy - because fat is less dense than water it is used to float

Protection - humans have fat around delicate organs to act as a shock absorber

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38
Q

Describe phospholipid structure

A

Has a phosphate group

1 glycerol

2 fatty acid tails

2?Ester bonds and 1 phosphester bond

3 condensation reactions , 3 lots of water released

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39
Q

Phospholipids behaviour in water

A

The phosphate head Has a negative charge , making it polar

However the fatty acid tails are non polar and so repel water

Head = hydrophilic -on the outside if the cell towards the solution
Tails=hydrophobic

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40
Q

What is cholesterol in plants called

A

Stigmasterol

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41
Q

Describe the structure of cholesterol

A

Type of lipid
Consists of 4 carbon based rings
Small and hydrophobic molecule
Sit in the middle of the hydrophobic part of the bilayer

42
Q

What’s the function of cholesterol

A

It regulates fluidity of the membrane , preventing it from becoming too fluid or stiff

Hormones made from cholesterol can diffuse straight through the bilayer

43
Q

Describe the structure of amino acids

A

Amino group

Central carbon

Carboxyl group

44
Q

What do buffers do

A

Resists changes in PH

45
Q

Describe the charge and electrons of water molecules

A

The oxygen atom has a greater number of positive protons in its nucleus this exerts a stronger attraction for the shared electrons , this means that oxygen atoms become slightly negative , and the hydrogen atoms become slightly positive, when this happens we call the molecule polar

Hydrogen bond

46
Q

Name the properties of water

A 
Liquid 
Density 
Solvent 
Cohesion and surface tension 
High specific heat capacity 
High latent heat of evaporation
47
Q

Describe the properties of water

LIQUID

A

The hydrogen bonds between water molecules make it more difficult for them to escape to become a gas, water has low viscosity which means it flows easily

Provide habitats for living things in rivers lakes and seas

Form major component of the tissue in living organisms

Provide a reaction medium for chemical reactions

Provide an effective transport medium

48
Q

describe liquid as a property of water

A

As in any liquid, water molecules constantly move around. Unlike
other liquids, as they move they continually make and break
hydrogen bonds (see topic 2.2.1, Figure 4).
The hydrogen bonds between water molecules make it more
difficult for them to escape to become a gas. By contrast, other
less polar, but similarly-sized molecules (e.g. H2S) are gases at
room temperature. Even with hydrogen bonds, water has quite a
low viscosity, which means it can flow easily
Because it is a liquid at room temperature, water can:
provide habitats for living things in rivers, lakes and seas
• form a major component of the tissues in living organisms
provide a reaction medium for chemical reactions
provide an effective transport medium; e.g. in blood and
vascular tissue.
-Provide a reaction medium for chemical reactions
- provide an effective transport medium

49
Q

Describe density as a property of water

A

The density of water provides an ideal habitat for living things. If
water was less dense, aquatic organisms would find it very difficult
to float.
When most liquids get colder, they become more dense. If this
were the case with water, then water at the top of a pond would
freeze and sink. The water replacing it at the top would do the
same, until the pond would be full of ice. But water behaves
differently It becomes more dense as it gets colder until about
4 oc. As it goes from 4 oc to freezing point, because of its polar
nature, the water molecules align themselves in a structure which
is less dense than liquid water
Because ice is less dense than water
• aquatic organisms have a stable environment in which to live
through the winter
• ponds and other bodies of water are insulated against extreme
cold. The layer of Ice reduces the rate of heat loss from the rest
of the pond.

50
Q

Describe solvent as a property as water

A

Water IS a good solvent for many substances found in living
things. This includes ionic solutes such as sodium chloride and
covalent solutes such as glucose. Because water is polar, the
positive and negative parts of the water molecules are attractedt(
the negative and positive parts of the solute. The water moleculet
cluster around these charged parts of the solute molecules or
and will help to separate them and keep them apart. At this point
they dissolve and a solution is formed.
Because water is such a good solvent:
• molecules and ions can move around and react together in
water Many such reactions happen in the cytoplasm of cells,
which is over 70% water.

molecules and Ions can be transported around living things whilst dissolved in water

51
Q

Describe cohesion and surface tension as a property of water

A

A drop of water on a flat surface does not spread out, but can look almost spherical , this is because hydrogen bonging between the molecules pulls them together , the water molecules demonstrate cohesion
can look almost spherical. This is because hydrogen bonding
between the molecules pulls them together. The water molecule
demonstrate cohesion.

This happens at the surface of water as well. The water molect
at the surface are all hydrogen-bonded to the molecules beneat
them, and hence more attracted to the water molecules beneav
than to the air molecules above. This means the surface of

52
Q

Describe water and the hydrogen bonds in water

A

Hydrogen bonds
Water consists of two hydrogen atoms, each covalently bonded to
one oxygen atom. However, because the oxygen atom has a greater
number of positive protons in its nucleus, this exerts a stronger
attraction for the shared electrons. This means the oxygen atom
becomes slightly negative, and the hydrogen atoms become slightly
positive: When this happens, we say the molecule is polar

53
Q

Describe high specific heat capacity as a property of water

A

Water temperature;is a measure of the kinetic energy of the water
molecules. Water molecules are held together quite t.ightly by
hydrogen bondi. Therefore, you have to put in a lot of heat energy
to increase their kinetic energy and temperature. The amount of
heat energy required is known as the specific heat capacity (4.2 kJ
of energy to raise the temperature of 1 kg of water by 1 OCY. This
means that water does not heat up or cool down easily Because
the main component of many living things is water, and many
organisms live in water, its high specific heat capacity is important:
• Living things, including prokaryotes and eukaryotes, need a
stable temperaturs for enzyme-controlled reactions to happen
properly.
Aquatic organisms need a stable environment in which to live

54
Q

Describe high latent heat of vaporisation as a property of water

A

High’ latent heat of vaporisation
When water evaporates, heat energy, known as the latent heat
of vaporisation, helps the molecules to break away from each
other to become a gas.\Because the molecules are held together
by hydrogen bonds, a relatively large amount of energy is needed
for water molecules to evaporate. Therefore, water can help to
cool livipg things and keep their temperature stabled For example,
mammals are cooled when sweat evaporates, and plants are
cooled when water evaporates from mesophyll cells.

55
Q

Describe being a reactant as a property of water

A

Reactant
Water is also a reactant in reactions such as photosynthesis,
and in hydrolysis reactions such as digestion of starch, proteins
and lipidsllts properties as a reactant do not directly draw on
its polarity, but its role as a reactant is extremely important for
digestion and synthesisof large biological molecules,

56
Q

Amino acids are joined together by covalent bonds called ? And involves a ? Reaction

A

Peptide

Condensation

57
Q

Two amino avid joined together are known as ?

A

Dipeptide

58
Q

Joining a longer chain of amino acids together forms a ?

A

Polypeptide

59
Q

What are the types of protein structures

A

Primary
Secondary
Tertiary
Quaternary

60
Q

Describe the primary structure

A

The sequence of amino vids found in a molecule

The order of amino acids in the primary structure will determine the shape of the protein molecule

Condensation reaction , peptide bonds

61
Q

Describe the secondary structure

A

The chain of amino acids is not straight. but twists into a shape called the secondary structure.
Some chains coil into an A-helix, with 36 amino acids per 10 turns of the helix. The helix is held
together by hydrogen bonds between the —NH group of one amino acid and the —CO group of
another four places ahead of it in the chain.
Other chains fold very slightly in a zig-zag structure. When one such chain folds over on itself, this
produces a “pleated sheet. •Hydrogen bonds between the —NH group of one amino acid and the
-CO group of another further down the strand hold the sheet together

62
Q

Describe the tertiary structure

A

Tertiary structure
When these coils and pleats themselves start to fold, along with areas of straight chains of
amino acids, this forms the tertiary structure. The tertiary structure is a very precise shape
which is held firmly in place by bonds between amino acidS which lie close to each other. The
tertiary structure may adopt a supercoiled shape (e.g in fibrous proteins) or a more spherical
shape (in globular proteins), as you will learn in topic 2.2.10.

63
Q

Describe quaternary structure

A

quaternary structure
- many proteins are made up of more than 1 polypeptide chain
-descfibes how multiple polypeptide chains are arranged to make the complete protein moleculf
This may also be held together with the same types of bond that hold the tertiary structure
together. See the quaternary structure of haemoglobin shown in topic 2.2.10.

64
Q

Describe protein bonding

A

Protein bonding
The primary structure of proteins, the chain of amino acids, is held together by peptide bond:
which are covalent bonds, and hence very strong. Other types of bond form between amino
acids in different parts of the polypeptide chain. These hold together the secondary, tertiary
quaternary structures. The secondary structure is primarily held together by hydrogen bonds
the tertiary structure and quaternary structure are held together by hydrogen bonds and many
others.

65
Q

Which bonds are found in tertiary and quaternary structure

A

Hydrogen
Ionic disulfide
Hydrophobic and hydrophilic interactions

66
Q

Describe hydrogen bonds

A

Hydrogen bonds forms between hydrogen atoms with a slight positive charge and other atoms with a slightly negative change - in amino acids these firm hydroxyl , carboxyl and amino groups

67
Q

Describe ionic bonds

A

Can form between those carboxyl and amino groups that are part of R groups . These ionise into NH+3 and COO- groups . Positive and negative groups like this are strongly attracted to each other to form an ionic bond

68
Q

Describe disulfide links

A

The R group of the amino acids cysteine contains sulfur . Disulfide bridges are formed between the R group of two cysteines . These are strong covalent bonds

69
Q

Describe hydrophobic and hydrophilic interactions

A

Hydrophobic parts of the R groups tend to associate together in
the centreof the polypeptide to avoid water. In the same way,
hydrophilic’parts are found at the edge of the polypeptide to be
close to water. iHydrophobic and hydrophilic interactions cause
twisting of the amino acid chain, which changes the shape of the
protein.frhese interactions can be a very important influence,
given that most proteins are to be found surrounded by water
inside a living organism.

70
Q

Describe fibrous proteins

A

Fibrous proteins have regular. repetitive sequences of amino
acids and are usually Insoluble In water These features enable
then to form fibres which tend to have a structural function.

71
Q

Describe globular proteins

A

Tend to roll up into almost spherical shape . Any hydrophobic R groups are turned onwards towaards the centre of the molecule , while hydrophilic groups are on the outside , this makes the protein water soluble , they also have specific shapes , which helps them to take up roles

72
Q

Examples of fibrous proteins

A

Collagen
keratin
Elastin

73
Q

Describe collagen function and where it’s found and why

A

Function is to provide mechanical strength

  • in artery walls a layer of Collagen prevents the artery bursting when withstanding high pressure from blood being pumped by the heart
  • tendons are made form collagen and connect muscles to bones allowing them to pull on bones
74
Q

Describe keratin

A

Keratin
Keratin is rich in cysteine so lots of disulfide bridges form between
its polypeptide chains. Alongside hydrogen bonding, this makes
the molecule very strong.
Keratin is found wherever a body part needs to be hard and strong
It is found in finger nails, hair, claws, hoofs, horns, scales, fur and
feathers. It provides mechanical protection, but also provides
an impermeable barrier to infection and, being waterproof, also
prevents entry of water-borne pollutants.

75
Q

Describe elastin

A

Elastin
Cross-linking and coiling make the structure of elastin strong and
extensible. It is found in living things where they need to stretch or
adapt their shape as part of life processes.
Skin can stretch around our bones and muscles because of elastin
Without elastin, skin would not go back to normal after being
pinched.
Elastin in our lungs allows them to inflate and deflate, and in our
bladder helps it to expand to hold urine.
Like collagen, elastin helps our blood vessels to stretch and recoil
as blood is pumped through them, helping maintain the pressure
wave of blood as it passes through.

76
Q

Examples of globular proteins

A

Haemoglobin
Insulin
Pepsin

77
Q

Describe haemoglobin

A

The quaternary structure of haemoglobin is made up of four polypeptides - two alpha globin chains and two beta chains , held together by hydrogen , ionic and disulfide links .

On the outside of each chain there is a space in which a haem group is held (prosthetic groups ) which contains and iron ion . A protein associated with this kind of group is called a conjugated protein

The function of haemoglobin is to carry oxygen from the lungs to the tissues

78
Q

Describe insulin

A

Insulin is made of two polypeptides chains. The A chain begins
with a section of a-helix, and the B chain ends with a section of
3-pleat. Both chains fold into a tertiary structure, and are then
joined together by disulfide links. Amino acids with hydrophilic R
groups are on the outside of the molecule, which makes it soluble
in water. Insulin binds to glycoprotein receptors on the outside of
muscle and fat cells to increase their uptake of glucose from the
blood, and to increase their rate of consumption of glucose.

79
Q

Describe pepsin

A

Pepsin is an enzyme that digests protein in the stomach. The
enzyme is made up of a single polypeptide chain of 327 amino
acids, but it folds into a symmetrical tertiary structure. Pepsin has
very few amino acids with basic R groups (only four), whereas it
has 43 amino acids with acidic R groups. This helps to explain
why it is so stable in the acidic environment of the stomach,
as there are few basic groups to accept H + ions, and therefore
there can be little effect on the enzyme’s structure. The tertiary
structure is also held together by hydrogen bonds and two
disulfide bridges.

80
Q

What is computer modelling of protein structure

A

a
Computer modelling of protein structure
Being able to predict the shape of a protein molecule from its
primary structure can be incredibly useful in biochemistry. For
example, predicting the occurrence of biologically active binding
sites on a protein molecule can help in identifying new medicines.
Scientists can predict protein shapes using computer modelling
techniques. As techniques for prediction of secondary structure
developed, they were based upon the probability of an amino
acid, or a sequence of amino acids, being in a particular
secondary structure. Such probabilities were derived from
‘already-known’ protein molecular structures.

81
Q

What are the two approaches to computer modelling of protein structure

A

Ab initio protein modelling

Comparative protein modelling

82
Q

Describe ab initio protein modelling

A

• Ab initio protein modellingl In this approach, a model is built
based on the physical and electrical properties of the atoms in
each amino acid in the sequence. With this technique, there can
be multiple solutions to the same amino acid sequence, and
other methods sometimes need applying to reduce the number
of solutions.

83
Q

Describe comparative protein modelling

A

One approach is protein
threading, which scans the amino acid sequence against a
database of solved structures and produces a set of possible
models which would match that sequence.

84
Q

Testing for starch

A

Add iodine solution to a sample

If starch is present , will see a colour change from yellow brown to blue / black

85
Q

Testing for reducing sugars

A

Benedicts test

Place a sample of food to be tested in a boiling tube , add Benedicts solution then heat in a water bath at 80 degrees Celsius for 3 mins , orange / red participate indicates a reducing sugar is present
When low levels of sugar are present It may appear yellow / green

86
Q

Testing for non reducing sugars

A

Non-reducing sugars
To test for a non-reducing sugar, we have to hydrolyse the bond
first, to ‘free up’ these ‘reducing groups’, and then test for reducing
• First, test a sample for reducing sugars to check there are none
there in the first place.
• Take a separate sample and boil it with hydrochloric acid to
hydrolyse the sucrose into glucose and fructose.
• Cool the solution and use sodium hydrogencarbonate solution
to neutralise it.
• Test for reducing sugars again.
A positive result (green-yellow-orange-red) indicates that non-
reducing sugar (e.g. sucrose) was present in the original sample.
In some cases, a sample may contain reducing and non-reducing
sugars. If you have a positive test for reducing sugars from your
first sample, you can go on to test for non-reducing sugars in an
equal-sized second sample. If present, the precipitate from this
second sample will have more mass than the precipitate from the
first sample. You can extract the precipitate from the mixture by
filtration.

87
Q

Testing for lipids

A

The emulsion test is used to test for the presence of lipids:
• Take a sample and mix it thoroughly with ethanol. Any lipid
will go into solution in the ethanol (remember that lipids are
not soluble in water).
• Filter.
• Pour the solution into water in a clean test tube.
A cloudy white emulsion indicates the presence of lipids. T}
is made up of tiny lipid droplets that come out of solution
when mixed with water

88
Q

Testing for proteins

A

For this you use the biuret test. If protein is present, the colour
changes from light blue to lilac , you may find the reagents are
supplied to you separately as biuret A (sodium hydroxide), which
you add first, and biuret B (copper sulfate), which you add next.
The colour is formed by a complex between the nitrogen atoms in
a peptide chain and Cu2+ ions, which is why this test really detects
the presence of peptide bonds.

place a sample of food
to be tested in a well
on a spotting tile

lilac colour indicates
protein is present

89
Q

Benedicts Reagent detects the presence of reducing sugars , if there is more sugar present :

A

The amount of precipitate will increase

The amount of copper ions remaining in solution will decrease

90
Q

How to use a colorimeter

A

A colorimeter works by shining light through a sample. Using a pipette, we can take the supernatant and place it in a cuvette (a small vial). which is then
placed into the colorimeter. The cuvette is commonly made of glass or plastic. Ensure you do not
leave a greasy fingerprint on the surface of the cuvette, as it could affect transmission of light.
Colour filters are often used for greater accuracy. By using a red filter in this case, we can shine red
light through the solution, and detect how much passes through (percentage transmission). The
solution reflects blue light but absorbs red light:
If there is a lot of unreacted copper sulfate, the supernatant is still quite blue, absorption of red
light is high and percentage transmission is low.
If there is little unreacted copper sulfate, the supernatant is less blue, absorption of red light is low
and percentage transmission is high.
When using a colorimeter, the device is usually zeroed between each ree
appropnate ‘blank’ sample to reset the 100% transmission / absorption

91
Q

How to create a calibration curve

A

1- take a series of known concentrations of reducing sugars
2- using a sample of each , carry out benedicts tests
3- use a colorimeter to record the percentage transmission of light through each supernatant
4- plot a graph to show transmission of light against the concentration of reducing sugars

92
Q

How do biosensors work

A

They take a biological or chemical variable which cannot be easily measured , and convert it into an electrical signal

93
Q

Application of biosensors

A

They can be used to detect contaminants in water , and pathogens and toxins in food. They can even be used to detect airborne bacteria

94
Q

What is the aim of chromatography

A

Is to separate a mixture into its constitutes ( biological molecules )

95
Q

What are the two components of chromatography

A

Stationary phase

Mobile phase

96
Q

Describe the stationary phase in chromatography

A

This is either the chromatography paper or a thin layer of chromatography plate . The paper is made of cellulose , the chromatography plate is often sheets of plastic covered with a thin layer of silica gel or aluminium hydroxide - in each case there are free -OH groups pointing outwards in contact with the mobile phase

97
Q

Describe the mobile phase in chromatography

A

This is the solvent for the biological molecules , we can use water for polar molecules or ethanol for non polar molecules . The mobile phase flows through and across the stationary phase , carrying the biological molecules with it

98
Q

What happened during chromatography and why

A

As the solvent travels up the paper or plate , the components of the solution mixture travels with it , they travel at different speeds so the pigments end up at different positions on the plate .

The speed at which molecules move along the paper or plate depends on their solubility in the Solvent and their polarity. Exposed -OH groups make the surface of the paper or plate very polar and allows it to form hydrogen bonds with the molecules. A highly polar solute will tend to stick to the surface (absorbed ) and hence move more slowly , a non polar solute will travel very quickly up the plate

99
Q

In chromatography how do you work out the relative distance travelled to help identify the pigment ( Rf)

A

Rf= x/y

X = measuring the distance fro the pencil line to the centre of the spot of pigment

Y= distance from pencil line to solvent front

100
Q

In chromatography Sometimes with colourless molecules , you cannot see where they Finish , what are the solutions

A

Ultraviolet light
Iodine
Ninhydrin

101
Q

What is chromatography used for

A

Commonly used to monitor the progress of reactions

Urine tests if athletes for illegal drugs

analysing drugs for purity of components

Analysis Of food to determine the presence of contaminants

Biology (10 decks)

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