Enzymes

Enzymes are Biological Catalysts

• They are proteins

• Catalysts speed up chemical reactions

• Structure = Function: Enzymes are specific to their Substrate (reactants). Active site of the enzymes fits together with the substrate(s)

• Different reactions require different enzymes

Enzyme Specificity - The shape of the enzyme (structure) fits it's substrate (function)

The induced-fit model is the more accurate model

Enzymes speed up chemical reactions (Catalysts)

• Activation energy is the energy needed to start a chemical reaction.

• The less activation energy needed (smaller hill to climb) the faster the reaction will happen

• Enzymes speed up reactions by lowering the activation energy

Factors affecting reaction rates

• Substrate concentration

• Enzyme concentration

• pH, temperature, and ion concentrations

Denaturation = to lose shape

• Structure (shape) = function

• If enzymes lose their shape they no longer function correctly

• Lower enzyme function = slower reaction rates

• Factors that can affect shape & function of enzymes: Temperature, pH, salinity (ion concentration)

Optimal Enzyme Function

When the reaction rate is the highest!

Multiple Choice

Enzymes are...

• nucleic acids
• proteins
• lipids
• carbohydrates

Multiple Choice

Any substance that is acted upon by an enzyme is called a(n)?

• Coenzyme
• Substrate
• Vitamin
• Polypeptide

Multiple Choice

Each enzyme only has 1 substrate that will fit its active site.  What is this called?

• reusablility
• denaturation
• specificity
• fragility

Multiple Choice

What is a substance called if it speeds up a chemical reaction?

• reusable
• catalyst
• specific
• fragile

Multiple Choice

What will most likely happen if an appropriate enzyme is added to a chemical reaction? 

• The reaction rate will increase.
• The equilibrium of the reaction will be maintained. 
• The reaction rate will decrease.
• The reaction will stop. 

Multiple Choice

Which of the following best explains why enzymes are necessary for many cellular reactions?

• Enzymes supply the oxygen necessary for the reactions
•  Enzymes change reactants from solid to liquids during the reactions.
• The reactions take up too much space in the cell if the enzymes are missing.
• The reactions are too slow to meet the needs of the cell if enzymes are missing. 

Multiple Choice

The diagram below illustrates a biochemical process that occurs in organisms. What is another name for the substance labeled "catalyst"?

• Enzyme
• inorganic compound
• Hormone
• Antibody

Multiple Choice

The graph shows how enzymes affect reactions in cells. Which statement best summarizes the information shown in the graph?

• Enzymes increase the energy of the reactants.
• Enzymes decrease the energy level of the products.
• Enzyme decrease the activation energy of the reaction.
• Enzymes reverse the direction of the reaction.

Multiple Choice

Which enzyme is most efficient in a basic solution?

• A
• B

Multiple Choice

What happens when enzymes are heated to a high temperature?

• The enzymes die.
• The shapes of the enzyme are altered denature
• The enzymes' amino acid sequence changes.
• The enzymes remain the same

Multiple Choice

Which of the following conclusions can be drawn from this graph?

• The optimum pH of the enzyme is 6.6.
  
• The optimum pH of the enzyme is 5.8
  
• The enzyme’s activity increases as pH increases 5.0 to 9.0
  
• The enzyme’s activity is greater around pH of 8.0 .
  

Multiple Choice

Enzymes are

• Lipids

• Protein

• Carbohydrates

• Nucleic Acids

Multiple Choice

Which of these is most likely an enzyme?  

• Sucrose

• Galactose

• Fructose

• Amylase

Multiple Choice

In the diagram, what is letter A? 

• product
• substrate
• enzyme-substrate complex
• active site

Multiple Choice

Letter D...

• active site

• enzyme

• substrate

• products

Multiple Choice

Letter B...

• active site

• enzyme

• substrate

• products

Multiple Choice

Letter c...

• active site

• enzyme

• substrate

• products

Multiple Choice

Each enzyme only has 1 substrate that will fit its active site.  What is this called?

• reusablility

• denaturation

• specificity

• fragility

Multiple Choice

After the enzyme and substrate bind together and perform the reaction, what does the substrate become?

• a substrate
• an enzyme
• a product
• an active site

Multiple Choice

What happens when enzymes are heated to a high temperature?

• The enzymes die.

• The shapes of the enzyme are altered denature

• The enzymes' amino acid sequence changes.

• The enzymes remain the same

Multiple Choice

Energy needed to get a reaction started

• catalytic energy

• kinetic energy

• covalent energy

• activation energy

Multiple Choice

How do enzymes affect chemical reactions?

• they prevent reactions from occuring

• providing energy directly to the reaction

• decreasing the amount of energy to get the reaction started

Multiple Choice

Enzymes that are denatured. . .

• have more energy

• have lost their 3-D shape and can no longer function

• are inactive until needed

• work more efficiently

Multiple Choice

What is an "active site"

• the substrate

• the place on the enzyme that interacts with the substrate

• the location, in the organelle, where the reaction occurs

• the entire enzyme

Multiple Choice

The molecule(s) that the enzymes bind to and change are called

• substrates

• denatured

• hydrolyzed

• active site

Multiple Choice

Which of the following affect enzyme reactions?

• temperature

• pH

• both temperature and pH

• nothing affects enzyme reactions

Multiple Choice

Which reaction is catalyzed by an enzyme?

• blue

• red

• both

• neither

Multiple Choice

This enzyme works best at a pH of

• 7

• 2

• 8

• works the same at any pH

Multiple Choice

In this reaction the reactant(s) is/are

• H2O2

• catalase

• H2O + O2

Multiple Choice

In this reaction the product(s) is/are

• H2O2

• catalase

• H2O + O2

Multiple Choice

In this reaction the enzyme is/are

• H2O2

• catalase

• H2O + O2

Multiple Choice

How does temperature affect this enzyme?

• the enzyme denatures above 23 degrees C.

• the enzyme works more slowly at 20 degrees C

• the enzymes works best at a temperature below 15 degrees C

• temperature does not affect this enzyme

Multiple Choice

What happens when enzymes are heated to a high temperature?

• The shape of the enzyme are changed and it denatures

• The enzymes die

• The enzymes' amino acid sequence changes

• The enzymes remain the same

Multiple Choice

What happens to an enzyme when it is denatured?

• Activation energy is lowered

• It becomes stronger

• It loses its shape

• Activation energy is raised

Multiple Choice

Absorbs energy

• endothermic reaction

• exothermic reaction

Multiple Choice

Releases energy

• endothermic reaction

• exothermic reaction

Multiple Choice

Which would be the enzyme that breaks down the starch amylose?

• amylase

• maltase

• lactase

• amylose

Multiple Choice

What is the optimum pH for the enzyme salivary amylase?

• 2

• 5

• 6.2

• 9.1

Multiple Choice

What is the optimum temperature for this enzyme?

• 20 degrees Celsius

• 45 degrees Celsius

• 52 degrees Celsius

• 64 degrees Celsius

Multiple Choice

How do enzymes speed up chemical reactions? Enzymes

• lower the activation energy of chemical reactions.

• raise the temperature of the cell, speeding chemical reactions.

• store ATP, allowing more energy to be used in chemical reactions.

• act as miniature "transfer trucks", gathering materials for chemical reactions, and placing them together.

Multiple Choice

Each enzyme produced by the body is

• open - meaning it is able to catalyze a reaction with any molecule.

• immature - meaning it cannot catalyze a reaction until many years later.

• incomplete - meaning it requires other parts before it is able to bind to a molecule.

• specific - meaning it is only able to catalyze a rection with a certain molecule.

Multiple Choice

What substances are formed as a result of this reaction?

• hydrogen peroxide and water

• water and oxygen

• hydrogen peroxide and oxygen

• water and ozone

Multiple Choice

Which model describes the active site of the enzyme changing shape slightly to fit the substrate?

• 'twisted ladder' model

• 'estimation' model

• 'induced fit' model

• 'lock and key' model

Multiple Choice

Which of the following describes the role that enzymes play in the process of metabolism?

• Enzymes carry the genetic instructions required for a cell to initiate metabolism.

• Enzymes increase the rate of the chemical reactions carried out during metabolism.

• Enzymes provide the chemical energy that is broken down and released during metabolism.

• Enzymes store the chemical energy that is used to construct nucleic acids during metabolism.

Multiple Choice

In the lock-and-key model of enzyme action, the __________ fits into the __________ of the enzyme.

• product; substrate

• active site; product

• substrate; active site

• active site; substrate

Multiple Choice

Where does the substrate bind on an enzyme?

• active site

• allosteric site

• binding site

• product site

Multiple Choice

catalyst =

• enzyme used to break down nucleic acids

• substance that speeds up the rate of a chemical reaction

• minerals that assist in the normal functioning of enzymes

• the part of an enzyme where the substrate binds to the enzyme and where the chemical reaction occurs