Enzymes (the small print) walk-around
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Describe the role of co enzymes
Give an example of a prosthetic group
How do the presence of inorganic ion co-factors affect
an enzyme controlled reaction?
Outline how potassium cyanide causes death
How can enzymes be used to treat cystic fibrosis?
Why is ethanol used to treat anti-freeze ingestion?
Describe how snake venom affects prey
State the meaning of the terms heterotroph and
endotherm
Explain why penicillin treats bacterial infections
Co-Enzymes
• Small non-protein molecules that bind for a short time to the active
site
• Bind either just before, or at the same time as the substrate
• Co-enzymes take part in the reaction and are changed in some
way, however they are recycled back to take part in the reaction
again
• Sometimes they carry chemical groups between enzymes linking
enzyme controlled reactions together
Example: vitamin B3 helps the body break down carbohydrates and fat. The
vitamin is used to make a co-enzyme that helps another enzyme : pyruvate
dehydrogenase, to function. Pyruvate dehydrogenase is involved in
respiration
Prosthetic Groups
• A co-enzyme that is a permanent part of
an enzyme molecule
• Also found in other protein molecules (not
just enzymes)
• They contribute to the final 3D shape and
other properties of proteins (like charge)
Example: the enzyme carbonic anhydrase contains a zinc based prosthetic
group. This enzyme is vital in red blood cells and helps to catalyse the
combining of carbon dioxide and water to make carbonic acid
Inorganic ion Co-factors
• The presence of certain ions can increase
reaction rate
• Ions can combine with an enzyme or substrate
• The binding of the ion makes the enzymesubstrate complex form more easily as it affects
the charge and shape of the enzyme-substrate
complex
Example: the enzyme amylase catalyses the breakdown of starch to
maltose- this enzyme will only function properly if chloride ions are present
Deadly Poisons
• Many poisons
inhibit or over
activate
enzymes
Example: potassium cyanide inhibits cell respiration. It is a non-competititive
inhibitor for a respiratory enzyme called cytochrome oxidase in mitochondria.
Inhibition of the enzyme decreases the use of oxygen, so ATP cannot be madethe organisms can only respire anaerobically, so lactic acid builds up in the
blood. Only 100-200mg is needed to make an adult unconscious in 10 seconds,
in a coma in 45 minutes, then die after 2 hours
Replacement Enzymes
• Cystic fibrosis is an
inherited disease
where the digestive
enzymes are blocked
from the pancreas
• Doctors provide
enzyme tablets with
an acid resistant coat
so they are not
destroyed in the
stomach
Ethylene Glycol Poisoning
• Ethylene glycol is anti-freeze
• If taken into the body, it is
broken down in the liver by the
enzyme alcohol
dehydrogenase to make oxalic
acid which is toxic and leads to
death
• In the hospital, a massive dose
of ethanol is given which is a
competitive inhibitor of alcohol
dehydrogenase, which
reduces the production of
oxalic acid
Snake Venom
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A mixture of toxins and
enzymes
Phosphodiesterases interfere
with the workings of the heart
causing a fall in blood pressure
Also present is an inhibitor of
the enzyme acetyl
cholinesterase involved in
nerve transmission- inhibition
of this enzyme results in
paralysis
In addition, the enzyme
hyaluronidase is a digestive
enzyme that breaks down
connective tissue and so helps
the toxins to penetrate the
tissues quickly
ATPases break down ATP to
disrupt the prey’s use of
energy
Antibiotics and Bacterial Enzymes
• Kill or inhibit the growth of
micro-organisms
• Penicillin inhibits an enzyme
that forms cross links in
bacterial cell walls halting
bacterial reproduction
• If a bacteria mutates with a
new enzyme controlling cell
wall growth bacteria are called
antibiotic resistant- they
already exist and produce an
enzyme called beta-lactamase
Heterotrophs
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Organisms that obtain their
nutrients by consuming other
organisms
They digest them by breaking
glycosidic, peptide and ester
bonds catalysed by enzymes
Many enzymes are extra-cellular,
meaning they are released from
the cells that make them onto food
within digestive system spaces
Other enzymes are found in the
cytoplasm of cells or attached to
cell membranes and they are
known as intracellular as their
action is within the cell
Example: mould produces extra cellular enzymes to digest bread
Endotherms
• Animals able to maintain an
internal body temperature
independently of the
environment
• Allows animals to live all over
the world
• The advantage is that
enzymes can therefore
function at a near optimum
level
• However this costs energy, so
a larger food intake is
generally required
Life in Extremes
• Some organisms can survive and grow in
extreme environments
Enzymes- Final Task
• Create a mind map with linking arrows to
include the following key words:
Substrate
active site
primary
Induced fit
co-enzyme
tertiary
lock and key
extracellular
Substrate concentration
competitive
globular
denature
R-groups
pH
prosthetic group
activation energy
intracellular
specificity
enzyme concentration
non-competitive
temperature
inhibitor
reaction rate