1. Chemical Reactions and Enzymes

2. Chemical Symbols Every element has the following Chemical symbol
Element # (proton #)
Atomic Mass
Every element has the following
Chemical symbol
Atomic Mass
Name
Element # (which is the same as the # of protons)
Chemical Symbol
Name

3. Introduction to Chemical Reactions
Making new substances

4. Main Ideas Chemical Reactions are represented by Chemical Equations.
Chemical Equations are balanced to show the same number of atoms of each element on each side.
The Law of Conservation of Mass says that atoms won’t be created or destroyed in a chemical reaction. That is why you have to balance chemical equations!

5. Chemical Reactions are Everywhere
Cooking
Respiration

6. Chemical Reactions are Everywhere
Hair Dye
Auto Fuel

7. How do you know when a chemical reaction takes place?
Color Change
Precipitate Formation

8. How do you know when a chemical reaction takes place?
Gas Formation
Odor

9. How do you know when a chemical reaction takes place?
Temperature Change
Change in Acidity

10. Representing Chemical Reactions
Chemists observe chemical reactions and have come up with a way to represent or model what is happening.
Making NaCl
Solid Sodium combines with Chlorine gas to make solid Sodium Chloride:
2Na (s) + Cl2 (g)  2NaCl

11. Chemical Equations are different from Numerical Equations
Numerical Equation: 3x + 2y = 47
Chemical Equation 2Na + Cl2  2NaCl
Reactant A + Reactant B  Product
The reactants are used up in forming the product
The arrow  shows the direction of the reaction

12. Symbols used in Chemical Equations
Purpose +
Separates more than one reactant or product 
Separates reactants from products. Indicates direction of reaction
(s)
Identifies a solid state
(aq)
Identifies that something is dissolved in water
(l)
Identifies liquid state
(g)
Identifies gaseous state

13. Law of Conservation of Mass
In a chemical reaction, matter is neither created nor destroyed.
Atoms won’t change their identity (e.g. a Carbon atom can’t become an Iron atom)
This means that you have to have the same number of each type of atom on each side of the chemical equation.
Conservation of Mass Video

14. How would you balance this equation?
Balancing Equations
After you write a chemical equation you have to balance it to make sure that the same number of atoms of each element are on each side.
How would you balance this equation?
Li + H2O  H2 + LiOH

15. Steps to Balancing a Chemical Equation
6. Check your work
5. Write the Coefficients in their lowest possible ratio
4. Change to Coefficients to make the number of atoms of each element equal on both sides of arrow
2Li(s) + 2 H2O  H2(g) + 2LiOH(aq)
3. Count the atoms of the elements in the products
1 atom Li, 3 atoms H, 1 atom O
2. Count the atoms of the elements in the reactants
1 atom Li, 2 atoms H, 1 atom O
1. Write the Skeleton Equation
Li(s) + H2O(l)  H2 (g) + LiOH (aq)

16. Another Example 7 ≠ 6! CH4 (methane gas) + O2  CO2 + H2O
Where did our atoms go?
Reactants
Products
# of Carbons = 1
# of Hydrogens = 4
# of Hydrogens = 2
# of Oxygens = 2
# of Oxygens = 3
Total atoms = 7
Total atoms = 6

17. Example Continued
Change the Coefficients to make the number of atoms of each element equal
Balance the Hydrogens:
CH4 + O2  CO H2O
Balance the Oxygens:
CH O2  CO H2O

18. Example Continued CH4 + 2 O2  CO2 + 2 H2O
Are your coefficients in their simplest ratio?
Count your atoms again to check your work:
Reactants
Products
# of Carbons = 1
# of Hydrogens = 4
# of Oxygens = 4
Total atoms = 9

19. Think – Pair - Share Try These! H2O -> H2 + O2
C6H12O6 + O2 -> CO2 + H2O
Think – Pair - Share

20. Review Matter is not destroyed or created
Atoms are rearranged in chemical reactions
Chemical equations represent chemical reactions
You have to have the same number of each type of atom on the left and right hand side of a chemical equation

21. Chemistry and Life
One unromantic yet productive way of viewing life is to see it as a set of coordinated chemical reactions.
This leads to an obvious question – What determines what chemical reactions are possible?

22. Chemical Reactions
Whether a chemical reaction will or won’t occur under particular conditions is determined by the laws of thermodynamics.
Keeping it simple -
If the overall amount of order is decreased by a reaction, the reaction is wanted an so requires little energy to get started. <SPONTANEOUS> - a lower energy level than the reactants
If the overall amount of order is increased by a reaction, the reaction is not wanted and so requires lots of energy to get started. <NON-SPONTANEOUS) - a higher energy level than the reactants

23. The Direction of Spontaneous Reactions (and what it takes to go the other way)
“Non-Spontaneous” Reaction – Takes energy to go this way

24. Energy of Activation (Ea)

25. ENZYMES Proteins that make YOU possible!
Speed up RXNs that happen too slowly to support life
Speed up RXNs necessary to survive/maintain homeostasis
Involved in the construction and maintenance of your body
Reduces the amount of energy needed to start a RXN
Cool Features of Enzymes
Made of proteins
Like any tool, can be reused thousands of times before needing to be replaced (enzymes are easily recycled by your body to make new enzymes)
Can be turned on or turned off depending on if they are needed
Most work for free -> no energy investment needed… though providing some energy can supercharge the enzyme to work even faster.
Copyright © 2009 Pearson Education, Inc.

26. 5.14 Enzymes speed up the cell’s chemical reactions by lowering energy barriers
Although there is a lot of potential energy in biological molecules, such as carbohydrates and others, it is not released spontaneously
You need energy to break bonds
This energy is called energy of activation (EA)
It is like the lift hill on a roller coaster.
Heat could be used to initiate a reaction. However, heat would kill the cell and would not be specific for a particular reaction.
For the BLAST Animation Enzymes: Activation Energy, go to Animation and Video Files.
Student Misconceptions and Concerns
1. For students not previously familiar with activation energy, analogies can make all the difference. Activation energy can be thought of as a small input that is needed to trigger a large output. This is like (a) an irritated person who needs only a bit more frustration to explode in anger, (b) small waves that lift debris over a dam, or (c) lighting a match around lighter fluid. In each situation, the output is much greater than the input.
Teaching Tips
1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
Copyright © 2009 Pearson Education, Inc.

27. Catalytic Enzymes speed up reactions
5.14 Enzymes speed up the cell’s chemical reactions by lowering energy barriers
Catalytic Enzymes speed up reactions
Enzymes speed up rxns by lowering EA
Enzymes are specific to their substrate.
Most enzymes are proteins, but RNA enzymes, also called ribozymes, also catalyze reactions.
Student Misconceptions and Concerns
1. For students not previously familiar with activation energy, analogies can make all the difference. Activation energy can be thought of as a small input that is needed to trigger a large output. This is like (a) an irritated person who needs only a bit more frustration to explode in anger, (b) small waves that lift debris over a dam, or (c) lighting a match around lighter fluid. In each situation, the output is much greater than the input.
Teaching Tips
1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
Copyright © 2009 Pearson Education, Inc.

28. Progress of the reaction
without
enzyme
EA without
enzyme
EA with
enzyme
Reactants
Energy
Net
change
in energy
(the same)
Reaction with
enzyme
Figure 5.14 The effect of an enzyme is to lower EA.
Products
Progress of the reaction

29. 5.15 A specific enzyme catalyzes each cellular reaction
Enzymes have unique three-dimensional shapes
The shape is critical to their role as biological catalysts
The shape includes an active site – spot where substrate binds
Enzymes will convert substrate to products
Student Misconceptions and Concerns
1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support.
Teaching Tips
1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments.
Youase
Copyright © 2009 Pearson Education, Inc.

30. Enzyme available with empty active site Active site Substrate1
Enzyme available
with empty active
site
Active site
Substrate
(sucrose) 2
Substrate binds
to enzyme with
induced fit
Enzyme
(sucrase)
Glucose
Fructose
Figure 5.15 The catalytic cycle of an enzyme. 4
Products are
released 3
Substrate is
converted to
products

31. 5.15 A specific enzyme catalyzes each cellular reaction
For optimum activity, enzymes require certain “Just right” environmental conditions
Temperature and pH
Certain chemicals also alter enzyme function and have been used to kill bacteria.
For the BLAST Animation Enzymes: Types and Specificity, go to Animation and Video Files.
Student Misconceptions and Concerns
1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support.
Teaching Tips
1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments.
Copyright © 2009 Pearson Education, Inc.

32. Inhibitors are chemicals that inhibit an enzyme’s activity
Controlling Enzymes
Inhibitors are chemicals that inhibit an enzyme’s activity
A substance that competes for the same active site as the substrate is called a competitive inhibitor.
Example of a common competitive inhibitor for your attention.
Penicillin, an antibiotic, is an example of a noncompetitive inhibitor because it blocks the active site of an enzyme that some bacteria use to make their cell wall.
For the BLAST Animation Enzyme Regulation: Chemical Modification, go to Animation and Video Files.
For the BLAST Animation Enzyme Regulation: Competitive Inhibition, go to Animation and Video Files.
Student Misconceptions and Concerns
1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support.
Teaching Tips
1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.)
3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.)
4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans.
Copyright © 2009 Pearson Education, Inc.

33. 5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell
Any inhibitor that interacts with the enzyme in a spot not used by the substrate is called a NON-COMPETITVE Inhibitor.
Non-Competitive Inhibitor
Student Misconceptions and Concerns
1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support.
Teaching Tips
1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids.
2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.)
3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.)
4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans.
Copyright © 2009 Pearson Education, Inc.

34. Normal binding of substrate
Active site
Enzyme
Normal binding of substrate
Competitive
inhibitor
Noncompetitive
inhibitor
Figure 5.16 How inhibitors interfere with substrate binding.
Enzyme inhibition