Transcript Molecular Madness

Chapter 9
Energy in a Cell
Section 9.1
The Need for Energy
• Explain why organisms need a
supply of energy.
• Describe how energy is stored and
released by ATP.
ATP: The Energy unit of the Cell
Adenine
NH2
N
O
O
-O
O
-
O
O
O
-
O
N
CH2
N
CH
C
N
O
H
Phosphate groups
C
HC
O
O
C
H
H
H
OH
Ribose
OH
ATP (adenosine triphosphate,三磷酸腺苷）
Cell Energy use in Active Transport
• Energy is released from ATP (-30.54 kJ/mol)
– When the terminal phosphate bond is broken
Section 9.2
Photosynthesis: Trapping the Sun’s Energy
• Relate the structure of chloroplasts
to the events in photosynthesis.
• Describe light-dependent reactions.
• Explain the reactions and products
of the lightindependent Calvin cycle.
Trapping Energy from Sunlight
• The process that uses the sun’s
energy to make simple sugars is
called photosynthesis(光合作用).
(P 225)
6 CO2 + 12 H2O + Light energy 
C6H12O6 + 6 O2 + 6 H2 O
Leaf cross section
Vein
Mesophyll
Stomata
CO2
O2
P 184
The Light-Dependent reactions
（光反应）
Light
Reflected
Light
Chloroplast
Absorbed
light
Granum
Transmitted
light
Pigments- light absorbing molecules
Chlorophyll a (main pigment in photosystem 1)
Chlorophyll b (main pigment in photosystem 2)
The Light-Dependent reactions
Photolysis
3H+= 1 ATP
• Chemiosmosis:
– Movement of chemicals across a selectively- permeable
membrane
H2O
CO2
Light
NADP

ADP
+ P
CALVIN
CYCLE
LIGHT REACTIONS
ATP
NADPH
Chloroplast
O2
[CH2O]
(sugar)
The Light-Independent reactions
Final Numbers
Light-Dependent
Reactions
Use
Produce
Sunlight
NADPH
H2O
ATP
O2
Light-Independent
Reactions
(Calvin Cycle)
Use
Produce
NADPH
RuBP
RuBP
ATP
PGAL (Which
form sugars)
CO2
NADP+/ADP/Pi
P 242
Section9.3
Getting Energy to Make ATP
• Compare and contrast cellular
respiration and fermentation.
• Explain how cells obtain energy
from cellular respiration.
Cellular Respiration (p 231)
• The process by which mitochondria
break down food molecules to
produce ATP is called cellular
respiration(细胞呼吸).
C6H12O6 + 6O2 = 6CO2 + 6H2O + ATP
Cellular Respiration
Electrons carried
via NADH and
FADH2
Electrons
carried
via NADH
Glucos
e
Citric
acid
cycle
Glycolsis
Pyruvate
Cytosol
ATP
Substrate-level
phosphorylation
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Mitochondrion
ATP
Substrate-level
phosphorylation
ATP
Oxidative
phosphorylation
Total
Cellular Respiration
NADH
2
FADH2
0
ATP
• Glycolysis (糖酵解)
– in the cytoplasm，break down glucose, into
two molecules of pyruvic acid a (3-C)
– is anaerobic—no oxygen is required.
– 2 ATP go in, 4 come out; Net Gain of 2 ATP
– Also produces 2 NADH
-2+4= 2
Cellular Respiration
Total
NADH
2+2= 4
FADH2
0
ATP
2
CO2
2
Total
Krebs Cycle
NADH
4+6= 10
FADH2
2
ATP
2+2= 4
CO2
2+4= 6
Electron Transport Chain
（电子传递链）
Total
NADH
-10
FADH2
-2
ATP
4+34= 38
CO2
6
H2O
6
2H+ = 1 ATP
Final Numbers…
Electron shuttles
span membrane
CYTOSOL
MITOCHONDRION
2 NADH
or
2 FADH2
2 NADH
2 NADH
Glycolysis
2
Acetyl
CoA
2
Pyruvate
Glucose
+ 2 ATP
6 NADH
Citric
acid
cycle
+ 2 ATP
by substrate-level
phosphorylation
Maximum per glucose:
by substrate-level
phosphorylation
About
36 or 38 ATP
2 FADH2
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ about 32 or 34 ATP
by oxidative phosphorylation, depending
on which shuttle transports electrons
from NADH in cytosol
Cellular Respiration
Fermentation (发酵)
• In the absence of oxygen，cells can still
produce ATP through fermentation
• There are two major types of fermentation:
lactic acid fermentation （乳酸发酵）
and alcoholic fermentation（酒精发酵）.
Glucose
CYTOSOL
Pyruvate
No O2 present
Fermentation
O2 present
Cellular respiration
MITOCHONDRION
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle
2 Ethanol
2 Acetaldehyde
Lactic Acid Fermentation
(b) Alcohol fermentation
2 ADP + 2
P1
2 ATP
• Fermentation allows constant energy
supply during exercise
Glucose
Glycolysis
• Lactic acid
can not be changedO–back into
C O
pyruvic acid in the cells
C O
• Liver has
enzymes
designed
to
convert
2 NADH
2 NAD+
CH3
O
lactic acid
C O
• Lactic acid builds up too fast and changes
H
OHthe pH of muscle cells
C
CH3 • Change in pH slows performance and
2 Lactate
weakens the muscle cells
(a) Lactic acid fermentation
Alcohol Fermentation
2 ADP + 2
Glucose
P1
2 ATP
Glycolysis
O
–
C
O
C
O
CH3
2 Pyruvate
2 NAD+
H
H
C
2 NADH
2 CO2
H
OH
CH3
2 Ethanol
(b) Alcohol fermentation
C
O
CH3
2 Acetaldehyde
P 235
Comparing
Photosynthesis and Cellular Respiration
P 237
That’s all