Enzymes
At what temperature is enzyme activity the greatest
At about 37 degrees Celsius
How do enzymes do this
By lowering the activation energy (the energy needed to start a reaction)
Why do cells use different enzymes to catalyze different reactions
Cells must use different enzymes to catalyze different reactions due to the specifications of the enzymes. Each enzyme has a shape specific to the shape of its substrate.
How are enzymes needed
Enzymes are needed in small quantities and can be reused
Is an enzyme "used up" by the reaction it catalyzes? Explain.
Enzymes are not used up by the reactions they catalyze. During a reaction, the enzyme combines loosely with its substrate. When the reaction is finished, the two separate, leaving the enzyme unchanged.
How do enzymes help accelerate reactions
Enzymes lower activation energy needed for chemical reaction
Increasing the temp. or pH will
Increase a reaction to a point at which it will then decrease (the enzyme will start to denature or break down)
Increasing the amount of substrate or enzyme will
Increase the reaction to a point at which it will remain constant
Could life exist without enzymes? Explain
It could not exist, because biochemical reactions of the life processes do not occur rapidly enough without enzymes to sustain life.
What are the 2 theoretical models for enzyme-substrate complexes
Lock and key and induced fit
Enzymes have_________
Optimum pH and temperatures (at which they work best)
Enzyme actions are ____
Reversible (a+b-> c and c->a+b)
The substance with which an enzyme reacts
Substrate
What is meant by enzyme specificity
The active site on an enzyme has a complex configuration with which only one substrate molecule fits. Thus, the enzyme forms a complex with only one type of molecule. Lock and key concept
What is the induced fit?
The enzyme adjusts to fit the substrate when it binds to it
What is the lock and key
The enzyme and the substrate match up and fit together like puzzle pieces
What is the x
The point of saturation
What do enzymes enter a reaction with?
They enter into the reaction with the substrate at the active site such as hydrogen bonds (a substrate which is H2O2)
What is the optimum ph for pepsin? As ph increases above that point, what happens to enzyme activity?
4.4; above that point, it's activity decreases
What are enzymes
Proteins
Enzymes are ____
Specific (fit together like a lock and key, 1000-4000 per cell with many ending in -ase)
What is the active site of an enzyme
The active site is the part of the enzyme into which the substrate fits.
How does increasing substrate concentration affect the rate of enzyme action when enzyme concentration remains constant
The rate if substrate action increases to a certain point, but above that point it remains constant
How does increasing enzyme concentration affect the rate of enzyme action when the substrate concentration remains constant
The rate of enzyme action increases at a certain point, but above that point it remains constant
Enzymes many be assisted by what
Coenzymes (such as vitamins)
In what way does an enzyme affect the reaction it catalyzes? How does the enzyme produce this effect?
An enzyme increases the rate of reaction it catalyzes. It does this by combining with the substrate to form a highly reactive enzyme-substrate complex. When the reaction is completed, the enzyme and newly formed reaction product separate.
How is the rate of enzyme reaction regulated?
By the relative amounts of enzyme and substrate
What are all enzymes
Catalysts but not all catalysts are enzymes
What is the relationship among enzymes, energy, and reaction rates
Chemical reactions cannot proceed without a certain level of energy, the activation energy. Typically, temperatures in a cell are not high enough to provide the activation energy. Enzymes speed the rates of reaction by lowering their activation energies
What are the characteristics of enzymes? Why are enzymes essential to life
Enzymes are usually proteins that speed up the rate of chemical reactions. Typically, an enzyme is specific for a chemical reaction. Without enzymes, chemical reactions would proceed too slowly for life to exist.
Describe and enzyme
Globular, usually quaternary structure
What do enzymes permit
Permit reactions to proceed under milder conditions of temperature and pH (human temp. of 98.6, blood pH near 7)
What is a catalyst
Substrates that cause a reaction to occur at a faster rate without being affected.