IB B IOLOGY Q UARTER 1 E XAM R EVIEW Topic 3.6 – Enzymes.
-
Upload
aryanna-hanby -
Category
Documents
-
view
221 -
download
2
Transcript of IB B IOLOGY Q UARTER 1 E XAM R EVIEW Topic 3.6 – Enzymes.
GUIDELINES
Get into a group of 4 Designate a recorder (you may rotate) In order to get points, your answer must be
written on the dry erase board When time is called, each group will raise
their answer/board up If your answer is correct, award yourself a
point (we’re on the honor policy ) I will take away points for disruptive behavior 1 minute per question
TOPIC 3.6 – ENZYMES
Why are enzymes called biological catalysts?
Because they speed up the rate of a reaction.
Reactants in the presence of an enzyme will form products at a faster rate than without an enzyme
TOPIC 3.6 – ENZYMES
Define: denaturation
When the specific shape the of the enzyme is changed, which alters the shape of the active site
The substrate and enzyme can no longer bond
Rate of reaction decreases
TOPIC 3.6 – ENZYMES
Outline the lock and key hypothesis used for enzyme-substrate activity.
Lock = enzyme’s active site Key = substrate Because the shape of the enzyme is
very specific, only one key (substrate will fit)
Enzymes and substrate are specific for each other
TOPIC 3.6 – ENZYMES
Define: active site
The area on an enzyme that binds to the substrate
Specific area responsible for the activity of all enzymes/proteins
TOPIC 3.6 – ENZYMES
Outline the induced fit model for enzyme-substrate activity.
The active site on the enzyme will slightly change its shape to form a tight bond with the substrate
TOPIC 3.6 – ENZYMES
True or false: An enzyme can force a reaction to take place.
False Enzymes cannot force reactions to
occur that would not otherwise take place
Enzymes only speed up the rate of reaction.
TOPIC 3.6 – ENZYMES
How do enzymes speed up the rate of reaction (think about activation energy)
The activation energy is the energy needed to start a reaction
Enzymes lower the activation energy Reactants are broken down to products
at a faster rate
TOPIC 3.6 – ENZYMES
Why are small amounts of enzyme effective in catalyzing a reaction?
Enzymes are reusable Once a substrate is converted to a
product, the active site on the enzyme is available for another substrate to bind
An enzyme can function as a catalyst many, many times
TOPIC 3.6 – ENZYMES
Identify the three factors that can effect enzyme activity.
Temperature pH Substrate concentration
TOPIC 3.6 – ENZYMES
Draw a graph showing the effects of temperature on enzyme activity. Be sure to include proper axis labels. Explain the effects of temperature on enzyme activity.
Graph: bell curve; increasing temp. on x-axis, rate of reaction on y-axis
At lower temperatures, molecules move slower less collisions between enzyme and substrate
As temperature increases, molecular movement increases more collisions
Peak of bell curve = optimal temperature After optimal temperature = denaturation
TOPIC 3.6 – ENZYMES Draw a graph showing the effects of pH on enzyme
activity. Be sure to include proper axis labels. Explain the effects of pH on enzyme activity.
Graph: bell curve; pH on x-axis, rate of reaction on y-axis
Too acidic = large number of hydrogen ions (H+) can bond to negative charges of the enzyme or substrate
Too basic = large number of hydroxide ions (OH-) can bond to positive charges of the enzyme or substrate
In either case, bonding between the enzyme and substrate is disrupted
Enzyme becomes less efficient, possibly inactive in extreme situations (denatured)
TOPIC 3.6 – ENZYMES
True or false: All enzymes work best at the same pH level
False – some prefer acidic environments (think pepsin in your stomach); some prefer neutral (think amylase in your mouth)
TOPIC 3.6 – ENZYMES Draw a graph showing the effects of substrate
concentration on enzyme activity. Be sure to include proper axis labels. Explain the effects of substrate concentration on enzyme activity.
Graph: linear increase in the beginning, followed by a plateau; x axis: increasing substrate concentration; y-axis: rate of reaction
As substrate concentration increases, so does rate of reaction because your have more substrate
There is a limit; as substrate out-numbers enzyme, the rate of reaction slows down because every enzyme molecule is working as fast as possible, so adding more substrate will not increase the reaction rate
TOPIC 3.6 – ENZYMES
When comparing/discussing data, what are important features you should include in your response?
Specific data Trends in data Units Objective terminology
TOPIC 3.6 – ENZYMES
In the lab you just completed, identify: the enzyme used and the substrate.
Pectinase Pectin
TOPIC 3.6 – ENZYMES
Maltose, a disaccharide, is a sugar used in the confectionary and brewing industries. Predict the name of the enzyme that breaks down maltose.
Maltase