Exam 2 (pre ME 2) Flashcards
(107 cards)
1
Q
Broad definition of photosynthesis
A
Process that converts solar energy into chemical energy
2
Q
Autotroph definition+types
A
Producers, self-feeders, produce organic molecules from CO2 and other inorganic molecules
Types
- Photoautotroph: light(almost all plants)
- Chemoautotroph: Chemicals(H2, H2S)
3
Q
Heterotroph definition+types
A
Obtain organic materials from other organisms
Types
- Get organic material from other living organisms
- Consume dead/nonliving organic material
4
Q
Chloroplasts
A
- Sites of photosynthesis
* Found mainly in mesophyll leaf cells
5
Q
Stomata
A
microscopic pores CO2 enters and O2 exits the leaf, located in mesophyll membrane
6
Q
Thylakoids
A
Connected sacs in the chloroplast that compose of a third membrane system
7
Q
Grana
A
(plural)stacks of thylakoids
8
Q
Chlorophyll
A
Pigment that gives leaves their green color, reside in thylakoid membranes
9
Q
Photosynthesis reaction and type
A
Redox, H2O is oxidized to O2 and CO2 is reduced to O2. Rxn is also anabolic and endergonic
Energy+6CO2+6H2O▶️C6H12O6+6O2
10
Q
How are photosynthesis and cellular respiration connected?
A
Photosynthesis generates O2 and organic molecules, which are used in cellular respiration, cellular respiration produces CO2 and H2O to be used in photosynthesis
11
Q
What are the parts of photosynthesis?
A
Light reactions(photo part) and calvin cycle(synthesis part)
12
Q
location of light reactions
A
in the thylakoids
13
Q
Purpose of light reactions
A
Split H2O, Release O2, reduce NADP+ to NADPH and generate ATP from ADP by photophosphorylation, convert solar energy to chemical energy
14
Q
What is the electron acceptor in photosynthesis?
A
NADP+
15
Q
Location of calvin cycle
A
stroma
16
Q
Purpose of calvin cycle
A
form sugar from CO2 using ATP and NADPH
17
Q
What is light used for in the light reactions?(general)
A
It drives the transfer of electrons and H ions from H2O to NADP+
18
Q
What happens to NADP+ in light reactions?
A
It is reduced to NADPH
19
Q
What is used in the light reactions?
A
Light, H2O, NADP+, ADP+P
20
Q
What is produced in the light reactions?
A
ATP, NADPH, O2
21
Q
Where do NADP+ and ADP+p for the light reactions come from?
A
They are products of the calvin cycle
22
Q
Where do the ATP and NADPH used in the calvin cycle come from?
A
They are products of the light reactions
23
Q
What is used in the calvin cycle
A
ATP and NADPH
24
Q
What is produced in the calvin cycle?
A
NADP+, ADP+P, and CH2O(sugar)
25
Types of pigments found in chloroplasts
Chlorophyll a: the key light-capturing pigment, does most of the work
Chlorophyll b: an accessory pigment
Carotenoids: a separate group of accessory pigments
26
Structural difference between chlorophyll a and b
Chlorophyll a has CH3 in its phosphyrin ring and chlorophyll b has CHO
27
Structure of chlorophyll pigments and their function
They have a phosphyrin ring at the head of the molecule that absorbs light with Mg at the center and a hydrocarbon tail that interacts with hydrophobic regions of proteins in the thylakoid membranes of chloroplasts, they have H atoms
28
What happens to a pigment molecule when it absorbs light
It goes from a stable ground state to an unstable excited state. They fall back to the ground state, releasing energy as heat
29
Fluorescence
Pigments that emit light in isolation, creating an afterglow
30
Photosystem
the reaction-center complex surrounded by light-harvesting complexes, located in thylakoid membrane
31
Reaction-center complex
Contains special pair of chlorophyll a molecules that experience electron excitation and the primary electron acceptor
32
Light-harvesting complexes
Contain chlorophyll pigments that transfer energy to the special pair of chlorophyll a molecules
33
Types of photosystems
Photosystem II(PS II): functions first, has P680 chlorophyll in reaction center that best absorbs light at the wavelength 680nm
Photosystem I(PS I): Functions second, has P700 reaction-center chlorophyll that best absorbs the 700nm wavelength
34
Why is photosystem II called PS II if it functions first?
The photosystems are named in their order of discovery
35
What type of electron flow occurs on the light reactions
linear/noncyclic
36
Steps of light reactions
1. A photon hits a pigment in a light-harvesting complex of PSII, its energy is passed along pigments until it excites P680
2. An excited electron from P680 is passed to the electron acceptor
3. H2O is split by enzymes, electrons are transferred from H atoms to P680+, reducing it to P680, O2 is released as a by-product
4. Electrons fall down ETC from PSII to PSI
5. Potential energy is stored in proton gradient
6. Transferred light energy and electrons from PSII excite and reduce P700+ to P700, giving an electron to its primary electron acceptor
7. Electrons fall down ETC from primary electron acceptor
8. NADP+ reduced to NADPH
37
How is H2O used in light reactions retrieved?
2H+ + (1/2)O2=H2O
38
At what point is O2 released in photosynthesis?
PSII of light reactions
39
What drives production of ATP?
chemiosmosis
40
Sequence of ETC between PSII and PSI
PSI, pq, cytochrome complex, pc, PSII
41
Sequence of ETC after PSI
PSI, fd, NADP+ reductase, NADPH
42
NADP+ reductase
catalyzes the transfer of electrons to NADP+, making NADPH by adding electrons and H+
43
General purpose of light reactions for the calvin cycle
light reactions provide chemical energy and reducing power the calvin cycle
44
Noncyclic electron flow and its limitation
makes equal amount of ATP and NADPH, usually more ATP than NADPH is needed
45
Cyclic electron flow
When electrons(during light reactions) cycle back from Fd to the PSI reaction center via pc. This produces ATP but not NADPH, no O2 is released
46
How and where is a proton gradient maintained in photosynthesis?
In chloroplasts, an ETC pumps protons into the thylakoid space, driving ATP synthesis as the diffuse back into the stroma
47
Chemiosmosis
creation of a proton gradient across a membrane to drive the synthesis of ATP.
48
Photophosphorylation
phosphorylation of ADP to form ATP using the energy of photons
49
Where does NADP+ get H+
the stroma
50
Chemiosmosis in photosynthesis
H2O is split, 4 protons are translocated across the membrane into the thylakoid space, a H+ is removed from the stroma and taken by NADP+
51
Main purpose of calvin cycle
use chemical energy of ATP and NADPH to reduce CO2 to sugar
52
Metabolism of calvin cycle and why
Anabolic, it builds sugar from smaller molecules using ATP and the reducing power of electrons carried by NADPH
53
Direct product of calvin cycle
glyceraldehyde 3-phosphate(G3P)
54
Net synthesis of one G3P
3 calvin cycles, fixing 3 molecules of CO2
55
Phases of calvin cycle
1. Carbon fixation
2. Reduction
3. Regeneration of the CO2 acceptor(RuBP)
56
Carbon fixation phase of calvin cycle
Calvin cycle incorporates each CO2 by attaching it to RuBP, catalyzed by rubisco
57
RuBP
5 carbon sugar that attaches to CO2 molecules in the calvin cycle, ribulose biphosphate
58
Rubisco
enzyme that catalyze attachment of CO2 and RuBP
59
What is done with the G3P from the calvin cycle
1 out of 6 is exported and used for making glucose or other products, 5 out of 6 us recycled to regenerate RuBP
60
How much CO2, ATP, and NADPH are used to synthesize one glucose/G3P molecule?
3 CO2
9 ATP
6 NADPH
61
Outputs of calvin cycle other than G3P
9 ADP, 8 P, 6 NADP+
62
How are 9 ATP put into the calvin cycle, but 9 ADP+8P are made?
1 of the P went to the G3P molecule
63
Photorespiration
Occurs in light, consumer O2 and produces CO2 like respiration, uses ATP, produces no sugar, happens in hot conditions
64
What is the secondary activity of RuBP?
oxygenase
65
C3 plants
first organic product of carbon fixation is a 3 carbon compound called 3-phosphoglycerate. Examples include rice, wheat and soybean
66
C4 plants
3 carbon compound as first product. Examples include corn and sugar cane
67
CAM plants
open their stomata at night and close them during the day, they take in CO2 at night, and use it in the calvin cycle during the day. Use crassulacean acid metabolism(CAM) to fix carbon. Example includes pineapples
68
Types of cells in leaves of C4 plants
Mesophyll and Bundle Sheath cells: In mesophyll, enzyme PEP carboxylase adds CO2 to PEP, forming a 4-carbon compound. These compounds are exported to bundle-sheath cells, where they release CO2 that enters the calvin cycle
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Similarities between C4 and CAM plants
they both incorporate CO2 into organic intermediates before entering the calvin cycle
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Differences between C4 and CAM plants
The C4 pathway spatially separates the initial steps of carbon fixation from the calvin cycle, while the CAM pathway separates them with time(temporal separation)
71
How do light reactions produce O2?
breakdown of H2O
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How do catabolic pathways release stored energy?
transferring electron
73
Reduction/oxidation
Reduction: gain electrons, gain energy
Oxidation: loses electrons
74
Cellular respiration reaction
C6H12O6+6O2 = 6CO2+6H2O
C6H12O6 is oxidized to CO2
6 O2 is reduced to H2O
75
NAD+
nicotinamide adenine dinucleotide, a coenzyme where electrons from organic compounds are usually first transferred in cellular respiration
76
FAD+
Flavin adenine dinucleotide, electron carrier during respiration, electron carrier
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Electrons carriers/shuttles
Carriers: oxidized form, missing H+
Shuttles: reduce form, have H+
78
Major pathways of cellular respiration
1. Glycolysis
2. Citric acid cycle(aka krebs or tricaroxylic acid cycle)
3. Oxidative Phosphorylation using ETC
79
Main goal of glycolysis, pyruvate oxidation, citric acid cycle and oxidative phosphorylation
Glycolysis: Each glucose molecule is broken down into 2 molecules of pyruvate
Pyruvate oxidation: Pyruvate enters mitochondria and oxidized to Acetyl CoA
Citric acid cycle: acetyl CoA is further oxidized to CO2
Oxidative phosphorylation: ETC converts chemical energy to a form that can be used in ATP synthesis in the process chemiosmosis
80
Oxidative phosphorylation general definition
Process that generates 90% of the ATP in cellular respiration, powered by redox reactions
81
Why does oxidative phosphorylation produce most of the ATP in cellular respiration?
it is powered by redox reactions
82
Substrate-level phosphorylation
a secondary pathway for ATP formation in glycolysis and the citric acid cycle, involves direct transfer of phosphate from another organic molecule to ATP
83
Phases of glycolysis and net products
1. Energy investment phase: 2 ATP are used to make 2 ADP+P. G3P produced
2. Energy payoff phase: 4 ADP+P are used to form 4 ATP and 2 NAD+ +4e-+4H+ make 2NADH and 2H+.
Both of the phases happen to glucose to yield 2 pyruvate and 2 H2O. A net yield of 2 ATP and 2NADH+2H+ happen from glycolysis
84
Pyruvate oxidation in cellular respiration
Pyruvate is oxidized to Acetyl CoA, pyruvate crosses membrane of mitochondria via transport protein, serves as junction of glycolysis and citric acid cycle, 1NAD+ makes NADH+H+ and CO2 is produced. Coenzyme A is added to pyruvate
85
Glycolysis location
cytosol outside the mitochondria
86
What process converts 1 glucose to 2 pyruvate?
substrate level-phosphorylation
87
inputs and outputs of 1 turn of the citric acid cycle
Input: Pyruvate
Output: 1 ATP, 3 NADH, 1 FADH2
88
Out of of citric acid cycle from 1 glucose
2 ATP, 8 NADH, 2 FADH2, 6 CO2,
89
ETC location(cellular respiration)
cristae of mitochondria
90
Electron transport chain in cellular respiration
Electrons are transferred from NADH OR FADH2 to the electron transport chain. Carriers alternate between reduced and oxidized states as they accept and donate electrons. Electrons reach oxygen to make water. Energy is released and sets up an electrochemical gradient across membrane
91
Which electron carriers are least electronegative in cellular respiration?
NADH, then FADH2
92
Cytochromes
part of the ETC with iron
93
Where is H+ pumped and where is there a gradient in cellular respiration?
The ETC is used to pump H+ from the mitochondrial matrix to the inter membrane space
94
Main parts of oxidative phosphorylation
1. ETC
| 2. Chemiosmosis (ATP synthase)
95
Which membranes/spaces are analogous in cellular respiration and photosynthesis?
Intermembrane space-thylakoid space
inner membrane-thylakoid membrane
matrix-stroma
96
Where do electrons come from in photosynthesis and cellular respiration?
Photosynthesis: water
Mitochondria: organic molecules
97
How do mitochondria and chloroplasts use chemiosmosis differently>
Mitchondria: transfer chemical energy from food molecules to ATP
Chloroplasts: Transfer light energy into chemical energy in ATP
98
How much ATP do NADH and FADH yield and which cells use them?
1 FADH=1.5 ATP, used in brain cells
1 NADH=2.5 ATP, used in liver and heart cells
99
How is ATP produced in glycolysis and the citric acid cycle?
Substrate-level phosphorylation
100
How much ATP does oxidative phosphorylation usually yield?
26-28 ATP
101
Anaerobic respiration
uses and ETC with a final electron acceptor other than oxygen
102
Fermentation
uses substrate-level phosphorylation instead of an ETC to generate ATP. Consist of glycolysis and reactions the regenerate NAD+ to be reused by glycolysis
103
Types of fermentation
Alcohol fermentation: used by yeast, no oxygen is involved, only glycolysis used, 2ATP is gained from glucose
Lactic acid fermentation: no oxygen, only glycolysis, pyruvate is reduced by NADH to NAD+ and lactate as end products, no CO2 released, net gain of 2ATP, used by some bacteria and fungi to make cheese and yogurt as well as human muscle cells, glycolysis occurs and of O2 isn't present this process occurs
104
What is special about yeast?
it uses aerobic respiration as well of alcohol fermentation
105
Similarities between fermentation, aerobic respiration and anaerobic respiration
All use glycolysis with a net gain of 2 ATP to oxidize glucose and harvest chemical energy for food, NAD+ is the oxidizing agent that accepts electrons during glycolysis
106
Differences between fermentation and cellular respiration
They have different mechanisms for oxidizing NADH to NAD+. In fermentation, an organic molecule such as pyruvate acts as the final electrons acceptor. They also have different net yields
107
Why is glycolysis a major intersection of metabolic processes?
is accepts a wide range of carbohydrates such as starch, glycogen and several dissacherides
