1. Intro to Cellular Processes and Enzymes

2. Heterotrophs (Consumers)
Organisms that cannot make their own food
They must eat and break down food in order to get energy
Can be:
1. Carnivores- eat mostly meat
2. Omnivores- eat meat and plants
3. Herbivores- eat mostly plants

3. Autotrophs (Producers)
Organisms that can make their own food
They must take in energy from the sun and take in CO2 molecules (from the atmosphere)
Combine to make sugars

4. Heterotrophs and Autotrophs are connected through Food Webs
Autotrophs make the molecules needed for heterotrophs

5. Harvesting stored energy
Energy is stored in macromolecules
carbohydrates, fats, proteins
Heterotrophs eat these organic molecules  food
digest organic molecules to get…
raw materials
fuels for energy
“burning” fuels in a series of step-by-step reactions
We eat to take in the fuels to make ATP which will then be used to help us build biomolecules and grow and move and… live!
heterotrophs = “fed by others”
vs.
autotrophs = “self-feeders”

6. Step-by-step reactions
Reactions in cells that are controlled by enzymes
Lots of small steps in order to have more control
Enzyme A
Enzyme B
Enzyme C
Step 1
Step 2
Step 3
Step 4

7. What Are Enzymes? Most enzymes are Proteins
Act as Catalyst to accelerate a reaction
Not permanently changed in the process

8. Enzymes Are specific for what they will catalyze Are Reusable
Names end in –ase
-Sucrase
-Lactase
-Maltase

9. How do enzymes Work?
Enzymes work by weakening bonds which lowers activation energy
Activation energy= energy required to start a reaction

10. Enzymes Without Enzyme With Enzyme Free Energy
Progress of the reaction
Reactants
Products
Free energy of activation

11. Enzyme-Substrate Complex
The substance (reactant) an enzyme acts on is the substrate
Enzyme
Joins
Substrate

12. Active Site
A specific region of an enzyme molecule which binds to the substrate.
Active Site
Enzyme
Substrate

13. “Lock and Key” Model
The substrate fits into the active site like a key fits into a lock
Only one type of substrate molecule can fit into the active site

14. Results of Chemical Reactions:
A product that the cell needs is made

15. What Affects Enzyme Activity?
Three factors:
1. Environmental Conditions
2. Concentration of Enzymes
3. Enzyme Inhibitors

16. 1. Environmental Conditions
1. Extreme Temperatures are the most dangerous
- high temps may unfold the enzyme = won’t work
pH (most like near neutral)

17. 2. Concentration of Enzyme
The more enzymes are present, the faster the reaction can occur
Rate of reaction will eventually level out once all substrate has been used up!

18. 3. Two examples of Enzyme Inhibitors
a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site.
Enzyme
Substrate
Competitive inhibitor

19. Inhibitors b. Noncompetitive inhibitors:
Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site.
Enzyme
Noncompetitive
Inhibitor
Substrate
active site
altered