1
Q
Energy
A
Ability to do work
2
Q
Kinetic energy
A
Energy due to movement
3
Q
Potential energy
A
Stored energy
4
Q
Chemical potential energy is ______
A
Stored up in the bonds of a molecule
5
Q
First Law of Thermodynamics
A
Total amount of energy in universe is constant (cannot be created or destroyed)
6
Q
How to find amount of energy in bond?
A
Break bond (bond energy measured in kJ/mol)
7
Q
The ___ the bond energy, the more _______ the bond
A
The greater the bond energy, the more chemically stable the bond
Bond stability not related to chemical reactivity
8
Q
Exothermic reactions
Endothermic reactions
A
Released
BreakingForming
9
Q
The molecule with the highest level of energy is
A
Transition state
Between reactants and products
10
Q
Energy transfer in a cell depends on
A
Bond energy
11
Q
Energy which is useful
A
Gibbs free energy
12
Q
Gibbs free energy (G)
Formula and neg/pos
A
Delta G = Gproducts - Greactants
- delta G -> spontaneous (respiration, bc less molecules -> more molecules)
(Exergonic)
+ delta G -> reactions that require energy (photosynthesis)
(Endergonic)
13
Q
Second Law of Thermodynamics
A
The universe is becoming more disordered (entropy - measure of disorder)
14
Q
Equilibrium
Delta G value
A
Equilibrium reactions convert back and forth with minimal energy
Delta G = 0
15
Q
Phosphorylation
A
Transfer of a phosphate group to another molecule
(transfer of energy, carried out by kinase)
- delta G (spontaneous)
16
Q
Redox
A
Reduction-oxidation reaction
Reactions involving electron transfer
17
Q
Reduction
Oxidation
Reducing agent
Oxidizing agent
A
LEO the lion says GER
Reduction - an atom gains electrons
Oxidation - an atom loses electrons
Reducing agent - loses electrons and causes other substance to be reduced
Oxidizing agent - gains electrons and causes other substance to be oxidized
18
Q
Goals of cellular respiration (3)
A
- Break 6 carbon glucose down and release 6 molecules of CO2
- Move glucose electrons to O2 and combine with H+ions to form 6 molecules of H2O
- Collect energy in the form of ATP
19
Q
Four major stages and locations
A
- Glycolysis - cytoplasm
- Oxidative carboxylation - mitochondrial matrix
- Kerbs cycle - mitochondrial matrix
- Electron Transport Chain (ETC) (oxidative phosphorylation / OXPHOS) - inner mitochondrial membrane
20
Q
Glycolysis
A
Breaking down glucose (6 C) into 2 pyruvate (3 C)
21
Q
Investment phase
A
Energy (ATP) used to split the molecule (steps 1-5)
22
Q
Pay-off phase
A
Energy molecules (ATP and NADH) are produced (steps 6-10)
23
Q
NAD+
NADH
A
NAD+ - nicotinamide adenine dinucleotide (oxidized form)
NADH - nicotinamide adenine dinucleotide (reduces form)
24
Q
NADH -(oxidation)-> NAD+ + ____
A
2e- + H+
25
Substrate-level phosphorylation
Oxidative phosphorylation (OXPHOS)
Location & explain
* glycolysis and Krebs cycle
* direct ATP formation through phosphate transfer from a molecule to ADP
* electron transport chain
* indirect ATP formation through redox reactions w O2 as final electron acceptor
26
Glycolysis Summary
1. Glucose -> 2 pyruvate
2. Net 2 ATP are produced (2 used 4 made)
3. 2 NADH produced
27
Gluconeogenesis
Generation of glucose from pyruvate
28
Aerobic metabolism
| What relies on O2
NADH and pyruvate will continue through Krebs cycle and the ETC to synthesize ATP only with O2
Without O2, cells need to make as much energy as possible w glycolysis
29
Anaerobic metabolism types (2)
Lactic acidosis fermentation (humans)
Alcohol fermentation (yeast)
30
Lactic acid fermentation
Lactic dehydrogenase:
Pyruvate -> lactic acid (lactate, 3 C)
(Turns back when there’s O2)
NADH -> NAD+
31
Alcohol fermentation
Pyruvate -(decarboxylated)-> acetaldehyde
(CO2 is released)
Alcohol dehydrogenase:
Acetaldehyde -> ethanol
NADH->NAD+
(Doesn’t turn back bc loss of CO2)
32
Oxidative decarboxylation
Rxn type
Enzyme
Energy
Decarboxylation
Redox
Synthesis
Decarboxylase
Dehydrogenase
Synthase
Released
33
Coenzyme A
Important functional group
also written as CoA-SH
Thiol
34
Oxidative Decarboxylation Summary
1. 2 pyruvate -> 2 acetyl-CoA
2. 2 CO2 released
3. 2 NADH produced
35
Krebs cycle overview
Aka?
Cyclical process to:
1. Produce CO2 molecules
2. Generate NADH, FADH2, ATP
Aka: citric acid cycle, tricarboxylic acid cycle (TCA)
36
FAD/FADH2
FAD - flavin adenine dinucleotide (oxidized form)
FADH2 - flavin adenine dinucleotide (reduced form)
37
Krebs cycle summary
```
1. Two cycles of Krebs for each glucose
(Per cycle):
2. Acetyl-CoA -> oxaloacetate
3. 2 CO2 produced
4. 3 NADH produced
5. 1 FADH2 produced
6. 1 ATP produced
```
38
Where are the matrix, inner mitochondrial membrane, outer mitochondrial membrane, and intermembranous space?
Check diagram
39
ETC
Electron Transport Chain
40
The ETC removes energy in NADH and FADH2 to:
What type of rxn
1. Make proton gradient across inner mitochondrial membrane
2. Convert O2 to H2O
ALL redox
41
Is the [H+] in intermembrane space more acidic or less acidic?
Is the [H+] in mitochondrial matrix more acidic or less acidic?
More acidic
Less acidic (on bottom where ATP is made)
42
Where are all the integral proteins
Inner mitochondrial membrane
43
What’s the order of the ETC components (NADH & FADH2)
NADH:
Complex I, Q, complex III,cyt c (peripheral), complex IV, ATP synthase
(3 proton pumps)
FADH2:
Complex II, Q, complex III, cyt c, complex IV, ATP synthase
(2 proton pumps)
44
Complex I
2 e- from NADH transferred here
Protons pumped across IMM
45
Q
e- from complex I transferred here
Mobile within IMM (still integral)
46
Complex III
e- from Q transferred here
Protons pumped across IMM
47
Cyt C
Peripheral
Mobile component on surface of IMM in intermembrane space
48
Complex IV
e- from cyt c transferred here
Protons pumped across IMM
49
O2
Final electron acceptor of ETC
Produces H2O molecules because enough e- pass through ETC to do so
NADH - electron donor
FADH2 - electron donor
50
NADH ->
| FADH2 ->
NAD+
| FAD
51
Complex II
2 e- from FADH2 to complex II
No protons are pumped across IMM
e- goes from complex II to Q and the rest of the ETC
52
ETC thermodynamics
Each electron transfer is energetically favourable
- delta G, spontaneous
(H2O is lower in energy than O2)
53
ETC summary
1. NADH e- transferred to O2; three proton pumps
2. FADH2 e- transferred to O2; two proton pumps
3. Electrochemical proton gradient formed across IMM (charge and conc diff - matrix is less positively charged)
54
Proton motive force
Chemiosmosis
electrochemical gradient sets up for chemiosmosis
Chemiosmosis occurs through enzyme complex ATP synthase (oxidative phosphorylation)
55
ATP Synthase Complex
Two components:
1. F0 - proton channel / rotor imbedded in IMM
2. F1 - catalytic site that phosphorylate ADP to ATP
56
ATP Production
Oxidative phosphorylation - ATP produced as protons go through ATP synthase using H+ gradient from ETC
1 NADH -> 3 ATP (3 proton pumps)
1 FADH2 -> 2 ATP (2 proton pumps)
ETC is coupled with ATP synthesis
ATP synthesis is dependent on ETC
57
Glycolysis NADH
Must be transported from cytoplasm into mitochondrion to enter ETC
Two shuttle mechanisms:
1. Glycerol phosphate shuttle
NADH e- to FADH2 e-
2. Malate-aspartate shuttle
NADH e- to NADH e-
(depending on the shuttle mechanism, 4-6 ATP is produced from glycolysis NADH)
58
ATP Production Summary
Glycolysis:
2 ATP
2 NADH (4-6 ATP)
Oxidative Decarboxylation:
2 NADH
Krebs Cycle:
6 NADH
2 FADH2
2 ATP
TOTAL: 36-38 ATP
59
Photosynthesis
Creating using light
CO2 + H2O -light-> O2 + C6H12O6
Only chloroplast organelles and special bacteria have necessary proteins for photosynthesis
60
What are the two major processes for photosynthesis
1. Light reactions
- using light energy to make ATP
2. Calvin cycle
- using CO2 an H2O to make C6H12O6
61
Chloroplast:
| Where are the outer membrane, inner membrane, stroma, granum, lumen, thylakoid
Check diagram
62
Steps of light reactions (3)
1. Photoexcitation
- absorption of light photons
2. Electron transport
- similar to ETC in mitochondria
3. Photophosphorylation (chemiosmosis)
- ATP synthesis due to electrochemical gradient
63
Photoexcitation
e- gains energy when atoms absorb energy
e- fall back to ground state if it isn’t transferred to another molecule
64
Ground state
The lowest energy level
65
Common light absorbing pigment
Chlorophyll - groups of light absorbing molecules in green plants (absorbs blue light the best)
(Hydrophobic tail, anchored to membrane)
66
Another light absorbing pigment
Carotenoids - other pigment molecules that can collect light energy (carrots)
67
Photosystem structure
* Chlorophyll and other light absorbing pigments
* in the thylakoid
* make a photosystem protein
• reaction centre - the chlorophyll a molecule (light is focused here in a photosystem)
68
Purposes of photosystems
1. Collect as much light energy as possible
| 2. Excited chlorophyll a and transfer its electron to an electron acceptor, and through proteins (electron transport)
69
Electron transport
Occurs in the thylakoid membrane
Two mechanisms:
1. Non-cyclic electron flow
2. Cyclic electron flow
70
Order for non-cyclic electron flow thylakoid membrane proteins?
PSII, Pq, cytochrome complex, Pc, PSI, Fd, NADP+ reductase, ATP synthase
71
PSII
```
Photosystem II (PS II) aka P680
(Max absorp at 680nm)
```
2 e- from H2O transferred here
light energy is needed to make O2 (excites electrons)
Protons are released into lumen (NOT pumped!)
72
Pq
Plastiquinone (Pq)
e- from PSII transferred here (only when PSII collects enough energy!)
Mobile within the thylakoid membrane (integral)
73
Cytochrome complex
e- from Pq to cytochrome complex
Protons pumped from stroma to lumen across thylakoid membrane
74
Pc
Plastocyanin (Pc)
e- from cytochrome complex transferred here
Mobile component on thylakoid surface in lumen (peripheral)
75
PSI
Photosystem I (PSI) aka P700
e- from Pc transferred here
(excites electrons)
76
Fd
Ferrodoxin (Fd)
e- from PSI transferred here (only when PSI has collected enough energy)
Mobile on thylakoid surface in stroma
77
NADP+ reductase
e- transferred from Fd to here
Final electron acceptor is NADP+ which is reduced to NADPH
78
NADP+
NADPH
oxidized
reduced
79
ATP synthase(thylakoid)
Protons pumped into lumen pass through ATP synthase
ATP produced in stroma
Photophosphorylation (light-dependent formation of ATP by chemiosmosis)
80
Non-cyclic electron transfer summary
1. H2O is split to produce O2 (released from cell) and H+ ions (releases into lumen)
2. Enzyme complexes pump proton from stroma to lumen
3. NADP+ is final electron acceptor and produces NADPH
4. Chemiosmosis to synthesize ATP
81
Cyclic electron transfer summary
1. Only PSI
2. Fd returns e- to cytochrome complex
3. Protons pumped into lumen to make more ATP (chemiosmosis)
4. No NADPH produced
82
Calvin cycle overview
A cyclical process which:
1. Fixes carbon (make C-C bonds)
2. Utilizes energy molecules
3. Regenerates molecules for another cycle
* occurs in stroma
* not as linear as Krebs
83
Carbon fixation
1. Three CO2 (1 carbon) are attached to three 1,5-ribulose bisphosphate (5 carbon)
2. Three 6-carbon molecules are split into six 3-carbon molecules
(Uses rubisco)
84
Rubisco
* large, slow reacting enzyme
| * plants need a lot of rubisco for Calvin cycle (half the protein in leaf, most abundant protein on earth)
85
Energy utilization
ATP phosphorylates each 3-carbon molecule
NADPH used to make G3P
86
Regenerate molecules
1. 5 G3P and ATP to resynthesize 1,5-ribulose bisphosphate
2. 1 G3P used in another pathway
• 2 calvin cycles for 1 glucose
87
Calvin cycle overview
1. 6 CO2 molecules are fixed to make one glucose
2. ATP & NADPH molecules used
3. e- from H2O transferred through light reactions
88
Factors affecting photosynthesis overview
1. Light intensity, [CO2], and temperature
2. C3 plant limitations
3. C4 plants
4. CAM plants
89
Photosynthesis rate factors
1. Increased [CO2]
= increased photosynthesis
2. Increased temp
= increased photosynthesis
3. Increased light intensity
= increased photosynthesis
(Up to a plateau bc Calvin cycle cannot keep up with light reactions)
90
C3 plant limitations
Stomata are open during day and closed at night
When hot, plants close stomata and increase [O2] in cells
At high [O2], rubisco binds to O2 rather than CO2 in photorespiration that causes the plant to SKIP Calvin cycle -> glucose NOT produced
91
C4 plant adaptations
C4 plants have:
• mesophyll cell
• bundle-sheath cell
1. Mesophyll cells create 4-carbon molecules and release CO2 into bundle-sheath cells
2. Bundle-sheath cells only perform Calvin cycle
When hot, C4 cells provide enough CO2 to ensure rubisco does not bind to O2
92
CAM plant adaptations
Stomata are closed in the day and open at night
1. CO2 collected & used at night
2. CO2 released during daytime where ATP & NADPH is made to allow Calvin cycle to occur
