UEC senior 1 biology 独中高一生物 ATP

1. Chapter 6
Ong Yee Sing
2017

2. 6.1 Adenosine
triphosphate

3. Objectives
• Discuss the role of ATP in metabolism
• Describe the structure of ATP
• Describe how ATP provide energy
• Explain the reaction of a cell to the viability of ATP

4. • Saccharides are the main
source of energy for cells.
• Fats are the main energy
storage substances.
• Saccharides and fats have
to be oxidized to release
energy.
• Adenosine triphosphates
(ATPs) are the direct
energy carrier in the cells.
Energy substances

5. Function of ATP
• The energy released
from the ATP molecule
is utilized by the cell
to carry out all kinds
of activities. Examples:
• Contraction of
muscles
• Transmission of
nervous impulse
• Active transport of
substances
• Growth of cells and
cell division, etc.
ATP binding cassette (ABC) proteins
requires ATP to transport anthocyanin
into the vacuole.

6. Structure of ATP
• It is chiefly produced by the
mitochondria.
• The structural formula of ATP
can be simplified as
A—P~P~P
• A = adenosine (adenine + ribose)
• P = phosphate (one central
phosphorus atom surrounded by
four oxygen atoms)
• ~ = high energy phosphate bond

7. Hydrolysis of ATP
• A great amount of chemical energy in
the ATP molecule is stored in the high
energy phosphate bond.
• The hydrolysis of this bond releases
energy.
• This reaction is said to be exogernic放能.

9. Energy released
hydrolysis of ATP
and ADP
ATPase, water
ATP ⇋ ADP + Pi + 3.3 x 104 J/mol
ATPase, water
ADP ⇋ AMP + Pi + 2.8 x 104 J/mol
Reaction progression
Energy
ATP
ADP + Pi
AMP + Pi + Pi

10. AMP is not a high energy molecule
• In AMP, the phosphate is joined to the
adenosine with a phosphoester bond,
not the phosphate bond, which links a
phosphate group to another
phosphate group.
• Energy released when the
phosphoester bond is broken is not a
large amount (9.6 x 103 J/mol).
• AMP aka oxyadenosine
monophosphate of RNA.

11. [ATP]/[ADP] ratio
• The ratio of the content of AMP, ADP and
ATP in the cell can reflect the energy
condition of the cell and the direction of
metabolism in the cell.
• When the amount of ATP is high, this
shows that the quantity of energy in the
cell is sufficient
• The cell will limit or restrict the oxidation of
substances.
• The cell promotes the synthesis of
macromolecules such as glycogen and lipids to
store the excess energy.
• When the amount of ATP and ADP
decreases, this shows that the amount of
energy in the cell is not sufficient.
• The cell will promotes respiration so to
increase the production of energy.
• Macromolecules will be oxidized to produce
more ATP.
• The ratio of [ATP]/[ADP] in the cytosol is
typically 200:1 or more.

12. Quiz
• Based on the figure,
what is the ATP/ADP
ratio in this muscle cell?
ATP/ADP ratio
=
ATP
ADP
=
7mM
0.04mM
=
175
1

13. • ATP releases
energy is NOT a
reversible reaction,
but ADP can be
recycled to reform
ATP with energy
added.
• Generally different
enzymes are
involved in
hydrolysis and
synthesis of ADP.
ADP is recyclable

14. Synthesis of ATP vs hydrolysis of ATP
Synthesis of ATP Hydrolysis of ATP
Equation of reaction ADP + Pi + energy  ATP ATP  ADP + Pi + energy
Type of reaction Synthesis / Anabolism Hydrolysis / Catabolism
Enzyme ATP synthase ATPase
Source of energy
Light (photosynthesis)
Chemical (respiration)
High energy
phosphate bond
Energy conversion Storage Release
Function of energy Storage as ATP Utilized in cellular activities
Location of reaction Mitochondria, chloroplast Almost all parts in a cell

15. Conclusion
• Saccharides are the main source of energy for cells.
• Fats are the main energy storage substances.
• Adenosine triphosphates (ATPs) are the direct energy carrier in the
cells.
• ATP can be hydrolysed into ADP, which in turns can be hydrolysed into
AMP.

16. Quiz
• How many ATPs can be formed from 30 adenosine and 60 phosphate?
A. 10
B. 20
C. 30
D. 60