3.1 Enzymes

Macromolecules Review

​Living things are composed of 4 macromolecules:

• ​amino acids for polypeptides (proteins)

​• fatty acids for lipids

​• monosaccharides such as glucose for polysaccharides

​• nucleotides form polynucleotides (DNA & RNA)

​Macromolecules have simple and complex forms

​The next slides will test whether you remember the details of the slides you just read.

If you need to review the previous slides again, feel free to do so. ​

Multiple Choice

What do disaccharides, such as sucrose, and polysaccharides, such as starch, have in common?

• They are lipids made of fatty acids.
• They are proteins made of amino acids.
• They are nucleic acids made of nucleotides.
• They are carbohydrates made of simple sugars.

Multiple Choice

Which group of organic compounds contains fatty acids?

• Carbohydrates
• Lipids
• Nucleic Acids
• Proteins

Multiple Choice

Which of the following answers links a biomolecule with one of its proper functions?

• Lipids - Store genetic information
• Carbohydrates - short term energy storage
• Nucleic Acids - Catalyze reactions
• Proteins - long term energy storage

Multiple Choice

How many sugar-phosphate strands exist in each RNA molecule?

• 4
• 2
• 1
• None

Multiple Choice

Which organic macromolecules are composed of chains of amino acids that join to form the structural components of organisms.

• Carbohydrates
• Proteins
• Amino Acids
• Lipids

Multiple Choice

This diagram shows the molecular structure of glucose.

Simple sugars like glucose can be used to make larger organic molecules. Identify a larger molecule made from simple sugars.

• Carbohydrates
• Lipids
• Monosaccharides
• Amino Acids

Multiple Choice

The molecule in the diagram plays what role in the body?

• Releasing Energy
• Forming part of the sugar-phosphate backbone of DNA
• Storing Fat
• Controlling blood glucose levels

Multiple Choice

The monomers used to synthesize proteins are called ____________.

• Nucleotides
• Fatty Acids
• Amino Acids
• Sugars

Multiple Choice

What is a peptide bond?

• Bond that holds two amino acids together.
• A bond that holds hydrogen and oxygen molecules together.
• A bond that holds the phosphate group of one nucleotide and a sugar of a neighboring nucleotide.
• A bond that is formed by the sharing of electrons.

Multiple Choice

The diagram shows a bond forming between two amino acids. What is the name of this reaction?

• Dehydration Synthesis
• Hydrolysis
• Pepysis
• Oxidation

Multiple Choice

Enzymes are an example of

• Lipids

• Carbohydrate

• Protein

• Nucleic Acid

Multiple Choice

What is the purpose  of an enzyme?

• give permission for the reaction
• raise activation energy
• speed up reactions
• control how many reactions occur

​Enzymes

Enzymes are functional proteins (quarternary structure) that act as biological catalysts.

​

​Catalysts are substances that increase the rate of a chemical reaction without becoming part of being changed in the process.

​Enzymes

Enzymes can either break complex substances into simpler forms (catabolic), or build complex substances from simple molecules (anabolic).

​Key Terms

Catalyst - a substance that increases the rate of chemical reaction and is not changed by the reaction

​

​Enzymes - proteins that function as biological catalysts

​

​Chemical Reactions - joining or breaking down of substrates; can be anabolic or catabolic

​

​Substrates - molecule/s that undergo reactions

​

​Product - the result of a chemical reaction.

​Naming Enzymes

Enzymes are named according to the reaction that they catalyze. For example enzymes which catalyse the breakdown of carbohydrates are called Carbohydrases.

​

​- breaks down lipids = Lipases

​- breaks down proteins = Proteases

​- breaks down amylose (starch) = amylase

​- breaks down maltose = maltase

​- synthesizes ATP = ATP Synthase

Multiple Choice

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

• reusable
• catalyst
• specific
• fragile

Multiple Choice

Enzymes are an example of

• Lipids

• Carbohydrate

• Protein

• Nucleic Acid

Multiple Choice

Letter D...

• active site
• enzyme
• substrate
• products

Multiple Choice

Letter B...

• active site
• enzyme
• substrate
• products

Multiple Choice

Letter E...

• active site
• enzyme
• substrate
• products

Multiple Choice

This enzyme breaks down lactose.

• fructase

• amylase

• lactase

• maltase

​Lock and Key Mechanism

​A belief on how Enzymes catalyze reactions is the lock and key mechanism. This principle explains that in order for an enzyme to work it must perfectly fit to a molecule. Enzymes are therefore highly SPECIFIC.

​

​Lactase will only catalyze the breakdown of lactose into simple sugars but it will not work on any other disaccharide. It will certainly not work too on proteins of any kind.

​

​The fit has to be perfect much like a key and a lock.

​Lock and Key Mechanism

An area or a side of the enzyme have a particular shape (called Active Site) which lets in a very specific substrate just like a key to a lock.

​

​When they join together, they form an Enzyme-Substrate Complex where the substrate may either be broken down or merged with another substrate.

Lowering the Activation Energy

Enzymes generally lower activation energy by reducing the energy needed for reactants to come together and react. For example: Enzymes bring reactants together so they don't have to expend energy moving about until they collide at random.

​Active Site

Substrate is a term used for a substance before a reaction. It later on can change and if so, it is then called a product. Example when eating bread, the starch (or amylum) is the substrate and if the enzyme amylase binds with it, starch will be broken down into maltose. Maltose is therefore the product.

Multiple Choice

Where do substrates bind on an enzyme?

• voltage-gated channels
• surface receptor
• calcium channels
• active site

Multiple Choice

What is the energy needed to start an chemical reaction referred to?

• Cascading Energy
• Potential Energy 
• Kinetic Energy
• Activation energy

Multiple Choice

The enzyme known as ‘catalase’ is involved in the breakdown of hydrogen peroxide molecules into separate water and oxygen molecules. During this reaction, what happens to the ‘catalase’?

• The enzyme would become products: O2 and H20
  
• The enzyme would be fully used up and discarded.
• The enzyme would remain unchanged in any way.
• The enzyme would become a new type of enzyme.

Multiple Choice

What is being represented by the letter A in the image?

• Substrate
• Enzyme
• Product
• Complex

Multiple Choice

If an enzyme becomes over heated what effect, if any, will the heat have on the enzymatic activity? 

• The enzyme will not store much chemical energy.
• The enzyme will not be able to catalyze reactions.
• The enzyme will lose its net electrical charge.
• The enzyme will lose stored genetic information.

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 tasks listed below is most associated with enzymes?

• catalyze chemical reactions                  
• store genetic information       
• store chemical energy in the cell   
• dissolve nutrients and minerals 

Multiple Choice

Carbonic anhydrase is an enzyme involved in the reaction of carbon dioxide with water to form a molecule that dissolves well in the liquid part of blood. How does carbonic anhydrase affect the reaction of carbon dioxide with water?

• A. by making the reaction reversible

• B. by changing chemical products of the reaction

• C. by increasing the time needed for the reaction to occur

• D. by decreasing the amount of energy needed to complete the reaction

Multiple Choice

Each cell in the human body contains thousands of different enzymes responsible for regulating reactions within the cell. Why is a single enzyme unable to regulate a variety of reactions?

• A. The binding of a product and an enzyme is specific.

• B. The binding of a substrate and an enzyme is specific.

• C. The enzyme is consumed by the products of the reactions.

• D. The enzyme is consumed by the substrates of the reactions.

Multiple Choice

An enzyme speeds up a reaction by

• lowering the activation energy.
• raising the activation energy.
• releasing energy.
• absorbing energy.

Multiple Choice

Collisions are the result of _______ of the substrate and enzyme. Successful collisions are ones in which the substrate and active site correctly ______.

• random movements, align

• repulsion, repel

• cooling, attract

• denaturation, match up

Multiple Choice

Low temperatures result in _______ thermal energy for the activation of an enzyme-catalyzed reaction.

• insufficient

• overabundant

Multiple Choice

At temperatures above the optimum temperature, enzyme stability will _______.

• decrease

• increase

Multiple Choice

The loss of enzyme shape is called

• denaturation.

• stress.

• random movement.

• alignment.

Multiple Choice

Changing the pH alters the ______ of the enzyme, which then affects protein solubility and may change the shape of the molecule.

• charge

• stress

• speed

• alignment

Multiple Choice

T/F: All enzymes have the same optimum pH range.

• true

• false

Multiple Choice

Use the graph to answer the following question.

The graph shows how the activity of an enzyme changes at different temperatures. Which statement best describes what happens to the enzyme when the temperature of the reaction increases to 63°C?

• The enzyme is used up and the reaction stops.

• The enzyme begins to decrease the rate of the reaction.

• The enzyme continues to increase the rate of the reaction.

• The enzyme changes shape and can no longer speed up the reaction.

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

Allosteric inhibitors block the active site

• true

• false

Multiple Choice

Which of these is NOT true?

• Enzymes can denature (change shape) when the temperature gets too high.
• Enzymes can only be used once in a chemical reaction. 
• Extreme pH can denature enzymes.
• Enzymes speed up chemical reactions. 

Multiple Choice

What is an inhibitor?

• the region of an enzyme that attaches to a substrate

• a change in the shape of a protein

• substance that can bind to an enzyme and prevent the substrate from binding

• macromolecules that contain carbon, hydrogen, oxygen, and nitrogen

Multiple Choice

what part do the competitive inhibitors attach to?

• subtrate
• active site
• somewhere other than enzyme

Multiple Choice

What are vitamins and minerals?

• Part of our food, give us energy

• activators

• inhibitors

• enzymes

Multiple Choice

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

• the need for a coenzyme

• allosteric inhibition

• insufficient cofactors

• competitive inhibition

Match

Match the following

• Binds to active site to slow reaction

• Binds at a different spot on enzyme to change shape

• Binds to active site

• Speeds up a chemical reaction without being used up

• Part of enzyme where reactants bind to

Competitive

Allosteric

Substrate

Catalyst

Active Site

• Competitive

• Allosteric

• Substrate

• Catalyst

• Active Site