1. Enzymes: “Helper” Protein molecules

2. Flow of energy through life
Life is built on chemical reactions
EX: Digestion EX: Photosynthesis

3. Chemical Reactions
A process that changes one set of chemicals into another set of chemicals.
Reactants – elements or compounds that enter into a chemical reaction.
Products – elements or compounds that are produced in a chemical reaction.
Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products.

4. In a reaction, energy is either TAKEN IN
(ENDOTHERMIC) or GIVEN OFF (EXOTHERMIC).
Can you think of an everyday example of each type of reaction?

5. Chemical reactions of life
Processes of life
building molecules
synthesis
breaking down molecules
digestion + +

6. Nothing works without enzymes!
How important are enzymes?
all chemical reactions in living organisms require enzymes to work
building molecules
synthesis enzymes
breaking down molecules
digestive enzymes
Catalyst - enzymes speed up reactions
without entering the reaction itself.
enzyme +
enzyme
We can’t live without enzymes! +

7. Examples
synthesis
enzyme +
digestion
enzyme +

8. Enzymes are proteins
Each enzyme is the specific helper to a specific reaction
each enzyme needs to be the right shape for the job
enzymes are named for the reaction they help
sucrase breaks down sucrose
proteases break down proteins
lipases break down lipids
DNA polymerase builds DNA
Oh, I get it!
They end in -ase

9. Enzymes aren’t used up Enzymes are not changed by the reaction
used only temporarily
re-used again for the same reaction with other molecules
very little enzyme needed to help in many reactions
substrate
product
active site
enzyme

10. It’s shape that matters!
Lock & Key model
shape of protein allows enzyme & substrate to fit
specific enzyme for each specific reaction

11. 1 2 3

12. Enzyme vocabulary Enzyme Substrate Enzyme-substrate complex
helper molecule
Substrate
molecule that enzymes work on
Enzyme-substrate complex
enzyme & molecule temporarily joined
Active site
part of enzyme that substrate molecule fits into

13. What affects how well an enzyme works?
Correct protein structure
correct order of amino acids
why? enzyme has to be right shape
Temperature
pH (acids & bases)

14. Enzyme concentration Effect on rates of enzyme activity
as you increase the amount of enzyme used, it increases how fast the reaction happens
more enzymes = more frequently they collide with substrate

15. Enzyme concentration reaction rate amount of enzyme
What’s happening here?!
Enzyme concentration
reaction rate
amount of enzyme

16. Substrate concentration
Effect on rates of enzyme activity
as you increase the amount of substrate used, it increases how fast the reaction happens
more substrate = more frequently they collide with enzyme

17. Substrate concentration
What’s happening here?!
Substrate concentration
reaction rate
amount of substrate

18. Temperature Effect on rates of enzyme activity Optimum temperature
greatest number of collisions between enzyme & substrate
human enzymes = 35°- 40°C (body temp = 37°C)
Raise temperature
denature protein = unfold = lose shape
Lower temperature T°
molecules move slower
decrease collisions

19. What’s happening here?!
Temperature
37°
reaction rate
temperature

20. How do cold-blooded creatures do it?
Enzymes work within narrow temperature ranges. Ectotherms, like snakes, do not use their metabolism extensively to regulate body temperature. Their body temperature is significantly influenced by environmental temperature. Desert reptiles can experience body temperature fluctuations of ~40°C (that’s a ~100°F span!).
What mechanism has evolved to allow their metabolic pathways to continue to function across that wide temperature span?

21. pH Effect on rates of enzyme activity pH changes protein shape
most human enzymes = pH 6-8
depends on where in body
pepsin (stomach) = pH 3
trypsin (small intestines) = pH 8

22. pH stomach pepsin intestines trypsin reaction rate pH 1 2 3 4 5 6 7 8
What’s happening here?! pH
stomach pepsin
intestines trypsin
reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH

23. For enzymes… What matters?
SHAPE!