Download Metabolic Activity

Metabolic Activity
Processing Energy: Photosynthesis; Glycolysis; Cellular Respiration
I.
Thermodynamic laws
A. Energy transformations
B. Entropy
II.
Utilizing energy and the atomic structure
A. Atomic structure
1- nucleus interactions
2- electrons and energy levels
3- ATP currency of all living things
B. Manipulating electrons and energy levels
III.
Biological systems and their energy transformations
A. living systems utilize controlled manipulation of energized
electrons for energy transformation (reduction-oxidation rxn)
B. enzymes assist living systems in energy transformations
C. energy transformations in living systems are strictly controlled
and released in “small manageable amounts”
D. two basic approaches to energy manipulation in living systems
1- autotrophy
2- heterotrophy
IV.
Photosynthesis: Fundamental steps
A. Fundamental concept: change light energy into chemical energy
6CO2 + 6H2O chlorophyll > C6H12O6 + 6O2
carbon dioxide & water => glucose & oxygen
B. Location of photosynthesis
1- prokaryotic cells
2- eukaryotic cells
C. The process:
1- Light reaction
a. light energy absorbed by chlorophyll
b. water split using light energy
1. oxygen gas released to atmosphere
2. hydrogen atoms lose an electron, to chlorophyll
3. hydrogen ions moved over to dark reaction to be used in
glucose production
c. light energy absorbed by chlorophyll used to energize electrons,
redox rxn
d. energized electrons first transferred to compound Q, electron
acceptor
e. controlled processing of energized electrons using a series of
electron acceptors
f. energy is thus released in small manageable amounts by
manipulating electrons through a series of redox
(reduction/oxidation) reactions
g. Energy used in this way is used to form ATP by bonding a
3rd phosphate group to a molecule of ADP and by moving
energized electrons to the nucleotide NADPox to form
NADPred
2- Dark reaction; also known as light independent reaction
a. carbon and oxygen from CO2 and hydrogen from H2O
are covalently bonded together to form the simple
sugar glucose (C6H12O6)
b. energy for bonding carbon, oxygen and hydrogen atoms
together comes from the ATP and NADPred generated
during the light reaction
c. six turns of the cycle are required to “fix” enough carbon
to form a single molecule of glucose (Calvin cycle)
D. Results
1- Light reaction: H2O is split,releasing oxygen gas (O2), hydrogen ions(H+)
as well as a continuous supply of electrons (from the hydrogen atoms)
2- Light reaction: light energy is transformed into chemical energy (ATP
and NADPred) by manipulating energized electrons
3- Dark reaction: energy is released from the bonds of ATP and NADPred
(which are generated during the light reaction) and then recaptured to bond
carbon, oxygen and hydrogen atoms together to form glucose.
E. Importance of photosynthesis to life on earth
1- Photosynthesis is the primary means by which carbon is incorporated
into living tissue and thus ultimately made available to all nonautotrophs
2- Photosynthesis is also the mechanism by which free oxygen is
released into the atmosphere (all aerobic process need this free oxygen)
V.
Mechanics of glycolysis and cellular respiration
A. Fundamental concept: change chemical energy (glucose) into
chemical energy (ATP)
C6H12O6 + 6O2 -----> 6CO2 + 6H2O + ATP
B. Location of glycolysis and cellular respiration
1- prokaryotic cells
2- eukaryotic cells
C. The process
1- Glycolysis (10 chemical rxns -enzyme assisted)
2- Oxidation of pyruvic acid to acetyl-CoA
3- Kreb’s cycle (citric acid cycle)
4- Electron transport chain
D. Results
1- Eventually, during glycolysis and cellular respiration, energy stored in
the bonds of glucose is released and then recaptured in the bonds of ATP, (chemical
energy to chemical energy transformation)
2- CO2 and H2O are by-products of cellular respiration
E. Importance of cellular respiration to life
1- Through glycolysis and cellular respiration energy stored in the bonds
of glucose is released and then recaptured to form ATP, which serves as the energy
currency of life.
F. Relationship between photosynthesis and cellular respiration
Vocabulary:
acetyl-CoA:
ATP (adenosine triphosphate):
autotrophy:
dark reaction (light independent):
electron transport chain:
FAD (flavine adenine dinucleotide):
glycolysis:
heterotrophy:
light reaction:
NAD (nicotinamide adenine dinucleotide):
NADP (nicotinamide adenine dinucleotide phosphate):
oxidation reaction:
pyruvic acid:
reduction reaction:
Study Questions:
1. What is the role of electrons in the energy transformations associated with
the light reaction of photosynthesis?
2. In the light reaction, light energy is “captured” in the form of chemical
energy. List the types of chemical energy formed during the light rxn.
3. Glucose is formed during the dark reaction of photosynthesis. The
energy in the bonds of glucose comes from the light reaction in what
form?
4. Describe what takes place when ADP and Pi are converted to ATP.
5. Where does the splitting of water take place in photosynthesis, and
what is the overall importance of this event to the process?
6. Discuss the differences between glycolysis and cellular respiration in
terms of location in eukaryotic cells.
7. How many ATP, NADPred and FADred are formed during the Kreb’s cycle?
8. Discuss what happens when NADPred is converted to NADPox.
Step I Glycolysis (cytoplasm)
GLUCOSE (6C)
2ATP ----------------> 2ADP + 2 Pi
4ADP + 4 Pi ---------------> 4ATP
2NADox + E- ---------------> 2 NADred
2 Pyruvic Acid (3C each)
(it is necessary to invest energy to make energy rich glucose unstable)
Step II Oxidation of Pyruvic Acid to Acetyl CoA (mitochondria)
2 Pyruvic Acid (3C each)
2CO
2
2NADox -----------------> 2 NADred
2 Acetyl Groups (2C each)
(enzyme)
2CoA
2Acetyl CoA
Kreb's Cycle (mitochondria) 8 steps in cycle
2 Co A
2 Oxaloacetic Acid
2 Citric Acid
6 NAD
ox
+ E- ------> 6NADred
2 FAD
ox
+ E- ------> 2FAD
red
2 ADP + 2 Pi ------> 2ATP
CO
2
Electron Transport Chain (mitochondria)
NADred
(controlled release of energy in small, manageable amts)
eADP + Pi
NADox
e-
ATP
ADP + Pi
e-
ATP
ADP + Pi
e-
ATP
e2H+ + 1/2 O2 =
H2O
Glycolysis & Respiration Summary (ATP from glucose)
ATP Direct NADred
FADred
Glycolysis Stage I
2
2*
0
Stage II
0
2
0
Kreb's Cycle Stage III
4*
6
2
Subtotal
6
10
2
Total ATP following Stage IV
6
30
4
(1 NADred = 3 ATP; 1FADred = 2 ATP)
Gross ATP Production from glucose......................................................
less ATP to start glycolysis & move FADred into mitochondria (-2 each)-4*
Net ATP Production from glucose.........................................................
40
36
Manipulation of Electrons
eelectron off to receptor
electron raised to
+
higher energy level
light energy
ee-
(c)
this or
this
energy released
(a) ground state
(b) excited state
e-
(d) back to ground state
The Flow Of Biological Energy
photosynthesis
cellular respiration
carbohydrate
(energy-rich)
O2
chloroplast
mitochondria
CO2 + H2O
(energy poor)
ATP for:
bioluminescence
biosynthesis
active transport
movement
electricity