1. Unit 4- Biochemistry, Energy, Enzymes
4b- Energy, Enzymes, ATP

2. Objectives!
Today, you will model the activity of an enzyme and how it functions to catalyze biochemical reactions.
Standards: H.B.2A The essential functions of a cell involve chemical reactions that take place between many different types of molecules (including carbohydrates, lipids, proteins and nucleic acids) and are catalyzed by enzymes.

3. Bellwork What is the role of an enzyme in the body?
What does an enzyme lower?
What factors affect enzymatic activity?
In the toothpick lab, what did the toothpick represent? What did your hands represent? What did the broken toothpicks represent?

4. Chemical Reactions
A chemical reaction breaks down some substances and builds other substances
2H2 + O > 2H2O
Biochemical Reactions allow organisms to grow, develop, reproduce, & adapt.
Reactants
Products

5. Chemical Reactions
Chemical Reactions can occur when reactants collide with enough energy to react.
The amount of energy that is sufficient for a particular chemical reaction to occur is called the activation energy.
Sometimes, a chemical reaction must absorb energy for the reaction to start (often in the form of heat)
Energy (as heat or light) can also be given off as a result of biochemical reactions
Ex- Cellular Respiration, Bioluminescence

6. Energy as heat/light
Cellular Respiration
Bioluminescence

7. Chemical Reactions
There are several factors that affect the rates of biochemical reactions.
Temperature – gaining or losing heat energy
pH – most organisms need to be kept in a small range of acidity for reactions to occur
Buffers within an organism regulate pH so homeostasis is maintained
A small change in pH can disrupt cell processes
Catalysts – substance that changes the rate of a reaction or allows the reaction to occur (activate) at a lower temperature
Work by lowering the activation energy of a reaction
Catalysts are not consumed or altered in a reaction, can be used over and over

8. Enzymes Enzymes are proteins that serve as catalysts in living things.
Enzymes are very specific.
Each particular enzyme can catalyze only one chemical reaction by working on one particular reactant (substrate)
Enzymes are involved in many of the chemical reactions necessary for organisms to live, reproduce, & grow.
Examples: digestion, respiration, reproduction, movement, and cell regulation
Enzymes speed up reactions that otherwise would occur too slowly at the body’s temperature
Reactions are able to occur at lower temperatures

9. Enzyme Names Enzymes will often end in the suffix –ase
The beginning of the name often tells you the substrate of the enzyme
Substrate: what an enzyme acts upon (the reactant)
Examples:
Amylase breaks down amylose (a component of starch)
Lactase breaks down lactose (a sugar in dairy products)
Lactose intolerant people lack the enzyme lactase

10. Induced Fit Model of Enzyme Action
Enzyme reactions depend on a physical fit between the enzyme & the substrate
Lock & key hypothesis
Induced fit- enzyme changes shape as the substrate molecules get close.
change in shape is “induced” by the substrate
The induced fit theory assumes that the substrate plays a role in determining the final shape of the enzyme and that the enzyme is partially flexible. This explains why some compounds can bind to the enzyme but do not react because the enzyme has been distorted too much. Only the proper substrate is capable of inducing the proper alignment of the active site.

11. Induced Fit Model of Enzyme Action
Substrate fits at the active site
Enzyme-substrate complex; reaction intermediate
This formation has a lower activation energy than the reaction between reactants without a catalyst
Reaction occurs and products released.
Enzyme is back to its original shape & ready to act again
The induced fit theory assumes that the substrate plays a role in determining the final shape of the enzyme and that the enzyme is partially flexible. This explains why some compounds can bind to the enzyme but do not react because the enzyme has been distorted too much. Only the proper substrate is capable of inducing the proper alignment of the active site.

12. Factors that Affect Enzyme Activity
Temperature
Each type of enzyme has a temperature range at which it works best.
Enzyme activity increases as the environment reaches that ideal temperature
Activity slows outside of that range. pH
Enzymes have a specific pH range at which they will work
At an extreme temperature or pH, an enzyme can denature (change shape and become ineffective)

13. Factors that Affect Enzyme Activity
Enzyme Concentration
If the amount of substrate stays the same, the rate of reaction will increase if the enzyme concentration increases
Reaction rate will drop if it runs out of substrate
Substrate Concentration
If the amount of enzyme stays the same, the rate of reaction will increase if the substrate concentration increases
Reaction rate will level off when all of the enzymes are working
Constant enzyme concentration

14. ATP Life processes require a constant supply of energy.
Cells use energy that is stored in the bonds of certain biological molecules.
Adenosine triphosphate (ATP) is a molecule that transfers energy from the breakdown of food molecules to cell processes.
ATP supplies energy that can be used quickly and easily by cells

15. ATP Structure A molecule of ATP is composed of 3 parts:
A nitrogen base (adenine)
A sugar (ribose)
Three phosphate groups that are bonded together by “high energy” bonds

16. ATP  ADP
The energy stored in ATP is released when a phosphate group is removed from the molecule.
This energy drives the cell’s metabolism.
When the phosphate is removed, ATP becomes ADP- adenosine diphosphate.
ATP ADP + phosphate + energy available for cell processes

17. ADP ATP
To supply the cell with energy, ADP is continually converted to ATP during the process of cellular respiration.
As the cell requires more energy, it uses energy from the breakdown of food molecules to attach a free phosphate group to an ADP molecule to make ATP.
ADP + phosphate + energy from breakdown of food molecules  ATP

18. ATP Recap
ATP is consumed by energy-requiring processes and can be generated by energy-releasing processes.
ATP transfers energy between separate biochemical reactions in the cell.
ATP is the main energy source for the majority of cellular functions
Including: synthesis of macromolecules like DNA and proteins
It also plays a key role in the transport of macromolecules across cell membranes

19. Watch!