Enzyme Lesson

Enzymes

Biological Catalysts

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

Multiple Choice

Enzymes are...

• nucleic acids
• proteins
• lipids
• carbohydrates

Multiple Choice

In the diagram, what is letter A? 

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

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

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

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.

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

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 .