bellringer-3/9/15 - weebly
TRANSCRIPT
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1. Based on your homework reading, what
is an enzyme?
2. Some reactions have enzymes. What
might be an advantage to having
enzymes in chemical reactions? Any
disadvantages?
3. Can you name any enzymes?
BELLRINGER-3/9/15
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ENZYMES
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Most enzymes are proteins
Act as a catalyst to speed up a chemical
reaction by helping molecules react with each
other faster
WHAT IS AN ENZYME?
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Reusable!
Specific for what they catalyze (speed up)
End in “-ase”
Named for the reaction they help. For example…
Sucrase breaks down sucrose
Proteases break down proteins
Lipases break down lipids
DNA polymerase builds DNA
ENZYMES ARE…
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Lactase breaks down lactose, a common component of dairy products (like milk)
People lacking the enzyme lactase are considered “lactose intolerant”-they can’t digest large amounts of milk!!
CASE STUDY: LACTOSE INTOLERANCE
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Re-used again for the same reaction with
other molecules
Very little enzyme is needed to help in many
reactions!
ENZYMES ARE NOT USED UP!
Products
Substrate
Active Site
Enzyme
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Remember, enzymes are
specific!
Lock and Key Model: Shape
of enzyme allows substrate
to fit
Specific enzyme for each
specific reaction
LOCK AND KEY MODEL
Chemical Reaction
Enzyme + Substrate Enzyme + Product
REACTANTS PRODUCTS
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Enzymes work by weakening bonds, which
lowers ACTIVATION ENERGY
Activation Energy=energy needed for the
chemical reaction to occur (energy needed to
activate!)
By lowering the activation energy, the reaction
can occur faster!
SO…HOW DO ENZYMES WORK?
Reactions can occur
without the help…but
not at the speed our
bodies need!
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Temperature
High temperatures can cause enzymes to denature (unfold and lose shape), while low temperatures slow molecules down
pH
Changes in pH changes protein shape (most human proteins sit at a pH of 6-8)
Denaturing=extreme temperature and pH can change enzyme shape, rendering it useless!
WHAT EFFECTS ENZYME ACTIVITY?
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Every reaction in your body is helped by an
enzyme. They are necessary for all biological
reactions!
WHY ARE ENZYMES IMPORTANT?
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Energy in the
cellPHOTOSYNTHESIS
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Process that uses the sun’s energy to make
glucose (food for the plant)
Performed in: Green plants and some bacteria
Occurs in the chloroplasts of the plant cell
WHAT IS PHOTOSYNTHESIS?
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PHOTOSYNTHESIS FORMULA
6CO2 + 6H2O C6H12O6 + 6O2Carbon dioxide water glucose oxygen
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The rate (speed) at which a plant performs photosynthesis is based on a number of things:
# of reactants
More reactants yields more products
Temperature and pH
Recall that enzymes are directly impacted by these factors!
Light
No light=no photosynthesis
RATE OF PHOTOSYNTHESIS
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Energy in the
CellCELLULAR RESPIRATION
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Process where molecules of glucose are
broken down to make CO2, water, and ATP
Occurs in the mitochondria of eukaryotes
WHAT IS CELLULAR RESPIRATION?
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RESPIRATION FORMULA
C6H12O6 + 6O2 6CO2 + 6H2O + ATPglucose oxygen carbon dioxide water energy
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The point of cellular respiration is to make
ATP!
ATP is ENERGY
All organisms require energy to live (movement, cell
division, active transport, etc…)
CELLULAR RESPIRATION
Three phosphates
Adenine
Ribose
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What do you notice about the relationship between the two processes?
PHOTOSYNTHESIS AND RESPIRATION
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Comparing
Energy
Processes
AEROBIC VS. ANAEROBIC
RESPIRATION
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Aerobic respiration takes place in the
presence of oxygen
This is most efficient-can produce up to 38
ATP per glucose!
Carried out in the mitochondria
AEROBIC RESPIRATION
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BUT WHAT IF OXYGEN ISN’T AVAILABLE?
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Anaerobic Respiration, like fermentation,
occurs when oxygen is NOT present
Less efficient-only 2 ATP produced!
Occurs in anaerobic bacteria, yeast, and
muscle cells
Carried out in the cytoplasm
ANAEROBIC RESPIRATION
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Alcoholic Fermentation
Occurs in bacteria,
yeast
Makes Ethanol
Used in making bread,
wine, and beer
Lactic Acid Fermentation
Occurs in muscle cells,
bacteria
Makes Lactic Acid
WHAT IS FERMENTATION?
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Anaerobic respiration can occur in muscle cells during
vigorous physical activity
Once your cells begin to lack sufficient oxygen, they
will switch to lactic acid fermentation
Lactic acid buildup and muscle fatigue leads to
cramping!
CASE STUDY: MUSCLE CRAMPS
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AEROBIC VS. ANAEROBIC
Krebs Cycle - 2 ATP
Electron Transport
Chain - 34 ATP
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AEROBIC VS. ANAEROBIC