Enzymes - Northwest ISD Moodle

advertisement
Enzymes
We couldn’t live with out them!
Intermediate 2
Castlehead High School
What is an enzyme?
• Known as a BIOLOGICAL CATALYST
• Catalyst is something that speeds up a
chemical reaction
• Biological catalyst speeds up reactions in
living cells
Castlehead High School
Activation Energy
• Do this by lowering the ACTIVATION
ENERGY - the energy required for a
reaction to begin
Energy
Uncatalysed reaction
Catalysed reaction
Progress of reaction
Castlehead High School
Properties of Enzymes
• They are made of PROTEIN
• They are not changed by the reactions
they speed up
• They are SPECIFIC- means that only one
particular enzyme will work with one
particular substrate
Castlehead High School
Other terms you need to know
• Substrate – the substance that the
enzyme works on e.g. Amylase the
substrate is starch
• Product – the substance that is made by
the reaction e.g. Breakdown of starch by
Amylase the product is Maltose
Castlehead High School
CATALASE
• Found in animal and plant cells
• Needed to speed up the breakdown of
HYDROGEN PEROXIDE
• Breaks it down to OXYGEN and WATER
• The word equation for this looks like this
OXYGEN AND WATER
HYDROGEN PEROXIDE
CATALASE
Castlehead High School
HPCOW
Amylase
• Found in saliva and in the pancreas
• Break down enzyme
• Breaks STARCH down to MALTOSE
• Word equation looks like this
STARCH
MALTOSE
AMYLASE
SAM
Castlehead High School
Potato Phosphorylase
• Synthesis enzyme (builds up)
• Builds Glucose-1-Phosphate molecules
into Starch
• The formation of starch is tested using
iodine solution
Starch
Glucose-1-Phosphate
Phosphorylase
G1PPS
Castlehead High School
More about Specific
• This means amylase will only breakdown
starch
• Catalase will only breakdown hydrogen
peroxide
• Amylase will NOT breakdown hydrogen
peroxide
• Catalase will NOT breakdown starch
Castlehead High School
Lock and Key
• All enzymes have a special shaped area
that fits onto their substrate
• This area is called the ACTIVE SITE
• This Active site will fit onto the substrate
while the reaction takes place
• Because it fits like a lock and key we call
this the lock and key mechanism
Castlehead High School
Model of Lock and Key
substrate
products
enzyme substrate complex
active site
enzyme
Castlehead High School
enzyme – unchanged
Effect of Temperature
• Speed of reaction increases until an
Optimum temperature is reached
• Optimum temperature is the temperature
at which the enzyme works best
• After this point the rate of reaction
decreases until there is no reaction
• At this point enzyme is said to be
DENATURED – active site destroyed
Castlehead High School
Effect of pH
• Most enzymes have an optimum pH of 7
• Some enzymes have a different optimum
pH for example pepsin has an optimum pH
of 2
Castlehead High School
More to do
• Click on links to go to website and do
Biology keystage 3 lessons 14,15,16,39
and 40
http://lgfl.skoool.co.uk/keystage3
• Also go to BBC bitesize standard grade
biology topic investigating cells Enzymes
and Aerobic Respiration
http://www.bbc.co.uk/scotland/education/bitesize/
Castlehead High School
Download