Honors Biology
Ch. 5 Notes online
Energy, ATP, Enzymes
5.12 Define and compare endergonic and exergonic
reactions
ender- inward
exer- outward
gonic- energy
Exergonic:
Releases energy overall
___H: “___________ change in heat content”
Reactants’ bonds contain more/less energy than the products’
bonds. “Up- or Downhill” energy reaction
These reactions feel ______.
Examples:

Wood burning

Sugar burning

Cellular ______________
Endergonic:
Requires energy overall
___H: “__________ change in heat content”
Reactants’ bonds contain more/less energy than the products’
bonds. “Up- or Downhill” energy reaction
These reactions feel _______.
Examples:

First aid cold pack

Photo___________
Metabolism: The total of an organism’s chemical reactions.
Which of the following is not a part of metabolism?
a. photosynthesis
b. hydrolysis of lipids
c. protein synthesis
d. blood typing
e. phagocytosis
f. dehydration synthesis
g. buffering of blood
5.12 Explain how cells use cellular respiration and energy
coupling to survive.
Energy coupling: the use of energy released from exergonic
reactions (“downhill”) to drive essential endergonic (“uphill”)
reactions. fig. 5.13c
Use a series of diagrams of energy couplings to show
photosynthesis, respiration, the ATP cycle, and energy to
do work. (The figure shows one circle out of four.)
5.13 Describe the three main types of work.
Chemical: synthesis of molecules
Mechanical: muscle contraction
Transport work: active transport by proteins.
5.13 Explain how ATP functions as an energy shuttle
Adenosine Triphosphate
ATP= the energy currency of the cell
Structure of ATP: 5.13a


A-PPP
Adenine + Ribose (adenosine) + PO4-3+ PO4-3 + PO4-3
Mrs. Loyd
cloyd@waukee.k12.ia.us
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http://loydbiology.weebly.com
10/20/11
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Energy Shuttle: fig. 5.13c
Phosphorylation:

High-energy bond + phosphate ( P ) transfer by
hydrolysis to molecule to do work.
draw ATP here

Adenosine Diphosphate

Adenosine Monophosphate
Summary:

ATP  ADP + Pi + 

ADP  AMP + Pi + 
Questions for Review
1. How many high-energy phosphate bonds does ATP
contain?
2. What does it mean when a molecule becomes
phosphorylated?
3. Where does the energy to do cellular work come from?
The hydrolysis of…
4. Is this reaction endergonic or exergonic?
5. Is cellular work an endergonic or exergonic reaction?
6. Where does the energy to make ATP come from?
The hydrolysis of…
7. Is this reaction endergonic or exergonic?
8. Is the synthesis of ATP endergonic or exergonic?
HOW ENZYMES FUNCTION
5.14 Explain how enzymes speed up chemical reactions.
Enzymes are:

Biological catalysts

Proteins made by cells

Structure determines function

Denatured proteins (unraveled) don’t work

Denaturation caused by:
o high temperatures shake apart tertiary structure
o extremes of pH
Enzymes:

lower the energy of activation (EA) to Cellular temperatures

have an active site that bonds their substrate

are SPECIFIC for their substrate

example: sucrase/sucrose fig. 5.15

are reused
5.15 Describe the structure of an enzyme-substrate interaction.
use induced fit to bond to substrate
(demo: meterstick-ase)
5.15 Explain how the cellular environment affects enzyme
activity.
Reaction Rates of Enzyme-Catalyzed reactions determined
by:

substrate concentration

enzyme concentration

temperature (optimum) body temp for humans

pH (optimum) pH = 6-8 for humans, buffers help

cofactors are required by many enzymes and may be:
o trace minerals (inorganic) or
o vitamin fragments (organic).

inhibitors (poisons are irreversible inhibitors)
Work Time: “ATP and Enzymes” (Weebly)
Mrs. Loyd
cloyd@waukee.k12.ia.us
Page 2 of 2
http://loydbiology.weebly.com
10/20/11
http://www.mybiology.com