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Glucose
Is a carbohydrate (made up of carbon, hydrogen and oxygen only)
Has the chemical formula C6H12O6 Is a monosaccharide (only made of
one molecule) Used as an energy source for respiration to make ATP
2 glucose molecules bonded together make maltose (a disaccharide
found in seeds) Many glucose molecules joined together form starch
The test for glucose is the Benedicts test
1. Place the substance you wish to test in a test tube (it must
be a liquid)2. Add a few drops of Benedicts solution3. Carefully
heat the test tube in a water bath (the water must be greater than
60OC4. If glucose is present there will be a colour change5. If
there is a small amount of glucose present the solution will turn
green6. If there is more glucose present the solution will turn
orange7. If there is a lot of glucose present the solution will
turn brick red
Starch
Is a carbohydrate (made up of carbon, hydrogen and oxygen only)
Polysaccharide made up more than 10 glucose molecules joined
together Is the energy storage molecule in plants (found in
amyloplasts) Is a large and insoluble molecule Is digested in the
body to produce glucose for respiration to produce ATP Foods that
are high in starch include: potatoes, bread & pasta The test
for starch is the Iodine test
1. Place the substance you wish to test into a test tube (it
must be liquid)2. Add a few drops of iodine solution (an
orange/brown colour)3. If starch is present the iodine will turn
blue/black4. The more starch there is the darker the colour change
will be
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Proteins
Used in organisms for growth and repair Contain the elements:
Carbon, Hydrogen, Oxygen, Nitrogen and many have Sulphur A polymer
made of amino acids joined together There are 20 different types of
amino acid What makes proteins different is the sequence of amino
acids they contain Proteins have a unique three dimensional shape
that help them with their function Haemoglobin, enzymes,
antibodies, keratin (found in skin, hair and finger nails) and some
hormones
(such as insulin) are examples of proteins
The test for proteins is the biuret test1. Place the substance
you wish to test into a test tube (it must be liquid)2. Add a few
drops of sodium hydroxide (NaOH)3. Add a few drops of copper (II)
sulphate (CuSO4)4. If protein is present the solution will turn
purple, if there is no protein the solution will stay blue
Lipids
Used as an energy store in the body Contain the elements carbon,
hydrogen and oxygen Fats & Oils are Triglycerides, a molecules
made up of a glycerol (C3H8O3) bonded to three fatty acids. Fat is
solid at room temperature (e.g. butter) Oils are liquid at room
temperature (e.g. olive oil) Saturated fats have no double bonds in
the hydrocarbon chain of the fatty acids (alkanes) Unsaturated fats
have at least one double bond in the hydrocarbon chain of the fatty
acids (alkenes) The test for lipids is the emulsion test
1. Place the substance you wish to test into a test tube (it
must be liquid)2. Add 2cm3 ethanol to the substance and shake the
test tube3. Add 2cm3 water to the test tube and shake again4. If
lipids are present the water will turn cloudy white
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DNA
The genetic material of a cell folded to form chromosomes A
double helix shape DNA is a polymer made up of many thousands of
units called a nucleotide A nucleotide is made up of three
molecules: a phosphate, a sugar and a base The sugar and phosphate
join up to form the backbone of the double helix The bases are held
together in the middle of the helix 4 bases in DNA called: Adenine,
Thymine, Guanine and Cytosine Adenine (A) pairs with Thymine (T)
Cytosine (C) pairs with Guanine (G) DNA makes new copies of itself
by splitting in half and each half becoming a template for a new
strand Small sections of DNA are called genes, each gene codes for
a protein In the first stage of protein synthesis DNA is read to
form mRNA a single stranded polynucleotide which
has the base Uracil (U) instead of Thymine
Enzymes
Enzymes are proteins Enzymes are biological catalysts they speed
up chemical reactions Enzymes can with break down molecules into
smaller ones or build up molecules into larger one. Each enzyme
control one particular chemical reaction; they are specific They
are unchanged after the reaction so can be used again and again
They have a unique 3D structure that form the active site that has
a complimentary shape to the
substrate of the reaction
The substrate fit in the active site to form the
enzyme/substrate complex, the reaction takes place andthe products
are released. This is called the Lock & Key Hypothesis
Enzymes are affected by temperature, at low temperatures there
is little kinetic energy so there areless collisions between the
enzymes and substrate so there is a low rate of reaction.
As the temperature increases so does the kinetic energy
therefore there are more collisions and therate of reaction
increases until it reaches its optimum temperature
At high temperatures the active site changes shape and no longer
fits the substrate, the rate ofreaction drops dramatically. The
enzyme has become denatured
Enzymes in the human body have an optimum temperature of around
37OC but not all enzymes workbest at that temperature
Enzymes are affected by pH. Each enzyme has an optimum pH, if
the enzyme is out of its optimum pHthen it will be become
denatured
Different enzymes have different optimum pHs
