ATP and ADP: Structure and function • Figure 2.15
a.
A TP structure and h yd ro lysis
When ATP is required for transferring energy, the terminal phosphate is
hydrolyzed to produce ADP and a free phosphate group. The reverse
reaction occurs when energy is transferred to ADP to make ATP
H C
Adenine
NH
2
/
її
і
V
C
^
C" H
O H
2
C
H
H
H
O-
1
O-
1
O-
1
0
1
- CL
1
0
1
0
1
- CL
У
b
1
- CL
У
II
II
II
O
O
O
3 phosphate groups Pi
OH
OH
Ribose
H C
Adenine
NH
2
/
її
і
\ - C
\..^ C“ H
H H
O-
1
O-
1
O-
1
0
1
- CL
1
0
1
■ 'P — OH +
0
1
- CL
1
0
1
II
II
II
O
O
O
2 phosphate groups Pi
1 phosphate group Pi
OH
OH
Ribose
Adenosine triphosphate (ATP)
Adenosine diphosphate (ADP)
2
H
H
Adenosine triphosphate (ATP)
+
H20
Adenosine diphosphate (ADP)
+
P,
+
Energy
b.
A T P p rovides energy
for
w ork done by ce lls su ch a s m em brane transport, m u scle contraction and ch em ical reactions.
3 Na+ expelled
2K+
P
3 Na'
Cytosol
K
ATP
2 K+
imported
P
'ADP
Na+/K+ ATPase
Na+
gradient
Extracellular fluid
gradient
Transporting ions across membranes like the sodium-potassium pump (transport work)
Contracted
M uscle contraction (m echanical
work)
Relaxed
C h em ical reactions (chem ical
work)
CH2OH
H
J—
-------O H
Glucose (1 molecule)
H
OH
Life Uses Important Chemicals 43
previous page 78 Craig Freudenrich, Gerard J  Tortora   Visualizing Anatomy and Physiology   2011 read online next page 80 Craig Freudenrich, Gerard J  Tortora   Visualizing Anatomy and Physiology   2011 read online Home Toggle text on/off