Bio Lect6 Flashcards
1
Q
What is photosynthesis?
A
A process that converts atmospheric CO2 and H2O to carbohydrates
Photosynthesis is essential for the production of glucose and oxygen in plants.
2
Q
What energy source is captured during photosynthesis?
A
Solar energy
Solar energy is captured in the chloroplasts during the light-dependent reactions.
3
Q
What are ATP and NADPH used for in photosynthesis?
A
To convert CO2 to hexose phosphates
This conversion occurs in the Calvin cycle.
4
Q
What are phototrophs?
A
Photosynthetic organisms
Examples include some bacteria, algae, and higher plants.
5
Q
What is the main division in photosynthesis?
A
Photosynthesis divides between ‘light’ and ‘dark’ reactions
6
Q
Where do light-dependent reactions occur?
A
In thylakoids
7
Q
Where do carbon fixation/ dark reactions occur?
A
In stroma
8
Q
What are the products of light-dependent reactions?
A
ATP and NADPH
9
Q
What cycle is involved in the dark reactions of photosynthesis?
A
Calvin cycle
10
Q
Fill in the blank: The light-dependent reactions convert _______ and uses _______ to convert water into ATP and NADPH.
A
water, light
11
Q
What is released as a byproduct of light-dependent reactions?
A
O2
12
Q
What do ATP and NADPH help to synthesize in the Calvin cycle?
A
Carbohydrates from CO2
13
Q
True or False: NADP+ is a product of the Calvin cycle.
A
False, it is carbohydrates
14
Q
What is released during the light reaction by splitting water?
A
O₂
O₂ stands for oxygen, which is a byproduct of photosynthesis.
15
Q
What do the light reactions take electrons from?
A
H
H refers to hydrogen, which is derived from water in the light reactions.
16
Q
What process uses light energy to produce ATP and NADPH?
A
Light reaction
ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) are energy carriers.
17
Q
What are ATP and NADPH used for in the dark reaction?
A
To make carbohydrates from CO₂ and water
CO₂ stands for carbon dioxide, which is a key reactant in the dark reaction.
18
Q
Fill in the blank: The light reaction splits water to release _______.
A
O₂
19
Q
Fill in the blank: In the dark reaction, ATP and NADPH are used to make carbohydrates from _______ and water.
A
CO₂
20
Q
What are light-dependent reactions?
A
Membrane-bound reactions that release O2 from splitting H2O molecules and produce ATP and NADPH
Light-dependent reactions are essential for the conversion of solar energy into chemical energy.
21
Q
What do light-dependent reactions release from splitting water?
A
O2
This process also involves the formation of hydrogen ions (H+) and the reduction of NADP+ to NADPH.
22
Q
What is the role of H+ from H2O in light-dependent reactions?
A
Used in the Chemiosmotic synthesis of ATP
This process involves the creation of a proton gradient that drives ATP synthesis.
23
Q
What is reduced to NADPH during light-dependent reactions?
A
NADP+
The reduction of NADP+ to NADPH is facilitated by the hydride ion (H:) from H2O.
24
Q
Where do dark (light-independent) reactions occur?
A
In the Stroma
The stroma is the fluid-filled space surrounding the thylakoids in chloroplasts.
25
What do dark reactions reduce CO2 to?
Carbohydrate
## Footnote
This process is part of the Calvin cycle, which synthesizes glucose from carbon dioxide.
26
What type of energy is required for dark reactions to occur?
Energy of NADPH and ATP
## Footnote
Dark reactions utilize the energy stored in NADPH and ATP produced during light-dependent reactions.
27
What is the process by which chloroplasts in plant cells move through the cytoplasm?
Cytoplasmic streaming (cyclosis)
## Footnote
This movement is driven by the actin-myosin cytoskeleton.
28
What drives the movement of chloroplasts in plant cells?
Actin-myosin cytoskeleton
## Footnote
This cytoskeleton facilitates cytoplasmic streaming.
29
Why do chloroplasts move within plant cells?
To optimize light absorption for photosynthesis and avoid damage from excessive light.
30
What happens to chloroplasts under low light conditions?
They spread out to maximize light capture.
31
What do chloroplasts do in high light conditions?
They relocate to shaded areas to prevent photodamage.
32
What is the purpose of the dynamic rearrangement of chloroplasts?
To ensure efficient energy production while protecting the cell's vital structures.
33
Fill in the blank: Chloroplasts move through the cytoplasm via _______.
cytoplasmic streaming (cyclosis)
34
What is the diameter range of chloroplasts?
4-8 mm
35
What are the two main structural components of chloroplasts?
Two surrounding membranes
36
What is the term for the internal membrane stacking found in chloroplasts?
Thylakoid membranes
37
What is the fluid-filled space inside chloroplasts called?
Stroma
38
Fill in the blank: Chloroplasts have _______ surrounding membranes.
two
39
True or False: Chloroplasts are organelles with a diameter of 4-8 mm.
True
40
What are lamellae in the context of chloroplast structure?
Internal membrane structures connecting thylakoids
41
What are the two envelopes of the cytoplasm?
Inner and outer envelope
42
The inner and internal membrane of the cytoplasm are similar to which organism?
Cyanobacteria
43
What structures do the inner and internal membranes contain that are also known as grana?
Stacks of thylakoids
44
What is a key structural feature of the thylakoids in the inner and internal membranes?
Strong lamely
45
How are the stacks of thylakoids connected within the cytoplasm?
Connected together and with the inner membrane
46
What technique is used to visualize the proteins in the photosynthetic reaction centres of thylakoid membranes?
Freeze-fracture EM of grana
## Footnote
This technique allows for the observation of proteins embedded in the membrane.
47
What is the process involved in Freeze-fracture EM of grana?
The tissue is frozen and then fractured with a diamond blade
## Footnote
This method fractures at the weakest point between the two halves of the lipid bilayer.
48
What do you observe in the thylakoid membrane using Freeze-fracture EM of grana?
An almost crystalline array of proteins
## Footnote
These proteins are embedded in the membrane where light is captured.
49
True or False: Freeze-fracture EM cuts through the tissue instead of fracturing it.
False
## Footnote
The technique fractures the tissue instead of cutting through it.
50
In Freeze-fracture EM of grana, what is created when the tissue is frozen?
A fracture at the weakest point of the bilayer
## Footnote
This allows for the visualization of the membrane structure.
51
What are chlorophylls and their importance?
Chlorophylls are the most abundant and important pigments in light harvesting.
## Footnote
Chlorophylls contain a tetrapyrrole ring (chlorin) similar to heme, but with Mg2+.
52
What are the two main types of chlorophyll found in plants?
Chlorophyll a (Chl a) and chlorophyll b (Chl b).
## Footnote
These are crucial for the photosynthetic process in plants.
53
What are bacteriochlorophylls?
Bacteriochlorophylls a (BChl a) and b (BChl b) are similar pigments found in anaerobic photosynthetic bacteria.
## Footnote
They perform a similar function to chlorophyll in different organisms.
54
What is the structural composition of chlorophyll?
Chlorophyll is made up of alternate double and single bonds.
## Footnote
This unique structure allows it to absorb light effectively.
55
Why is chlorophyll effective at absorbing visible light?
Its structure creates a large, shared cloud of electrons that allows absorption of visible light instead of just ultraviolet light.
56
What would happen if chlorophyll had only single bonds?
It would mostly absorb high-energy UV light, which isn't useful for photosynthesis.
57
Which colors of light does chlorophyll primarily absorb?
Chlorophyll absorbs red and blue light.
## Footnote
This absorption reflects green light, making plants appear green.
58
How does the flat shape of chlorophyll contribute to photosynthesis?
The flat shape helps capture more light when positioned correctly, making photosynthesis more efficient.
59
Fill in the blank: Chlorophyll allows plants to turn sunlight into _______.
energy
60
What are 'antenna' pigments?
Pigments that capture light for photosynthesis
## Footnote
Includes carotenoids, phycocyanin, and phycoerythrin.
61
Name three types of antenna pigments.
* Carotenoids
* Phycocyanin
* Phycoerythrin
## Footnote
These pigments absorb light that chlorophyll does not.
62
What is the role of pigments like carotenoids in photosynthesis?
They absorb light for photosynthesis
## Footnote
They capture wavelengths that chlorophyll cannot.
63
True or False: Chlorophyll absorbs all wavelengths of light.
False
## Footnote
Other pigments like carotenoids absorb light that chlorophyll does not.
64
Fill in the blank: The structure of different pigments is referred to as _______.
[antenna structure]
## Footnote
This refers to the arrangement of pigments that capture light.
65
What are 'antenna' pigments?
Pigments that capture light for photosynthesis
## Footnote
Includes carotenoids, phycocyanin, and phycoerythrin.
66
Name three types of antenna pigments.
* Carotenoids
* Phycocyanin
* Phycoerythrin
## Footnote
These pigments absorb light that chlorophyll does not.
67
What is the role of pigments like carotenoids in photosynthesis?
They absorb light for photosynthesis
## Footnote
They capture wavelengths that chlorophyll cannot.
68
True or False: Chlorophyll absorbs all wavelengths of light.
False
## Footnote
Other pigments like carotenoids , phycocyanin and phycoerythrin absorb light that chlorophyll does not.
69
Fill in the blank: The structure of different pigments is referred to as _______.
[antenna structure]
## Footnote
This refers to the arrangement of pigments that capture light.
70
What is the primary function of chlorophyll and other pigments?
Capture light
## Footnote
Chlorophyll absorbs specific wavelengths of light for photosynthesis.
71
What are antenna pigments?
Pigments that extend the range of light capture, especially in the green
## Footnote
Antenna pigments help improve the efficiency of light absorption.
72
What happens when antenna pigments and chlorophylls exchange light energy?
Excited electrons are captured
## Footnote
This process is essential for the conversion of light energy into chemical energy.
73
Name three types of pigments in antenna
* Carotenoids
* Phycocyanin
* Phycoerythrin
## Footnote
These pigments play various roles in light absorption and protection against photo-damage.
74
Fill in the blank: Antenna pigments help capture light in the _______ range.
green
## Footnote
Chlorophyll absorbs poorly in the green range, making antenna pigments crucial.
75
What wavelength range is associated with chlorophyll absorption?
400 to 700 nm
## Footnote
This range includes the visible spectrum of light utilized in photosynthesis.
76
What happens when light hits a molecule?
An electron absorbs the energy and jumps to a higher energy level
## Footnote
This process occurs extremely fast.
77
How quickly does an electron lose energy if it is not used?
Within nanoseconds (10⁻⁹ seconds)
## Footnote
The energy is often lost as heat or light.
78
How long do biochemical reactions, like splitting water in photosynthesis, typically take?
Milliseconds (10⁻³ seconds) or more
## Footnote
This duration creates a time gap in energy usage.
79
What problem do plants face regarding the energy absorbed from light?
The energy from light disappears too quickly to directly power slow biochemical processes
## Footnote
This necessitates a mechanism to store or transfer energy.
80
How do plants solve the problem of quickly fading energy from light?
Using antenna pigments and reaction centres. They pass energy between each other in picoseconds to nanoseconds (10⁻¹² to 10⁻⁹ seconds)
## Footnote
This process keeps the energy 'alive' until it reaches a reaction centre. These structures help in managing energy transfer efficiently.
81
What happens at the reaction centre during photosynthesis?
Energy is used to move electrons to start biochemical reactions
## Footnote
This is crucial for the process of photosynthesis.
82
What are the two types of Photosystems involved in light absorption?
Photosystems I (PSI) and II (PSII)
## Footnote
These Photosystems play a critical role in the photosynthetic process.
83
Where are the proteins and pigments of Photosystems I and II located?
Embedded in the thylakoid membrane
## Footnote
The thylakoid membrane is crucial for the light-dependent reactions of photosynthesis.
84
How do PSI and PSII operate in relation to each other?
In series, connected by cytochrome bf complex
## Footnote
This connection facilitates the transfer of electrons during the light reactions.
85
What is the final electron acceptor in the light absorption process?
NADP+
## Footnote
NADP+ is reduced to NADPH, which is used in the Calvin cycle.
86
Fill in the blank: Electrons are conducted from _______ to NADP+.
H2O
## Footnote
Water is split in the process, releasing oxygen as a byproduct.
87
What happens after an electron is captured in photosynthesis?
It is used to split water, resulting in an activated photosystem
## Footnote
This process is crucial for generating the necessary components for the photosynthetic electron transport chain.
88
What does the Z-scheme represent in photosynthesis?
The energetics of the reduction oxidation or redox state of compounds involved in light energy capture
## Footnote
The Z-scheme illustrates how energy is transformed and transferred during photosynthesis.
89
What are the two different wavelengths captured by photosystems?
Photosystem one captures light at a wavelength associated with chlorophyll a, while photosystem two captures light associated with chlorophyll b
## Footnote
This distinction is important for understanding the different roles of each photosystem.
90
What is the relationship between the Em value and reductive capacity?
The more negative the Em (ev), the more reductive
## Footnote
This relationship helps to identify the redox potentials of different compounds in the photosynthetic process.
91
What is the function of photosystem two?
To split water, releasing hydrogen and electrons
## Footnote
This reaction is essential for providing the electrons needed for the electron transport chain.
92
What happens to the electrons after they are excited in photosystem two?
They pass down through a cascade of redox reactions to release energy and eventually pass to cytochrome and then plastocyanin and then to photosystem one
## Footnote
This transfer of electrons is crucial for the production of ATP and NADPH.
93
What occurs in photosystem one with the excited electrons?
The electrons are passed to NADP+, reducing it to NADPH
## Footnote
NADPH serves as an energy carrier in the Calvin cycle.
94
What is the oxidation state of both photosystems in their unexcited state?
Both photosystem one and photosystem two are in their most oxidized state
## Footnote
This state is essential for their functionality in capturing light energy.
95
Where do all these processes of photosynthesis occur?
Inside the thylakoid membrane
## Footnote
The thylakoid membrane contains the necessary components for the light-dependent reactions.
96
What are the two Photosystems involved in light absorption?
PSI and PSII
## Footnote
Photosystems are essential components of the photosynthetic process.
97
What is the function of the reaction centre in Photosystems?
Site of the photochemical reaction
## Footnote
The reaction centre is where light energy is converted into chemical energy.
98
What is the role of chlorophylls in the reaction centre?
Paired to capture light
## Footnote
Chlorophylls are pigments that absorb light energy for photosynthesis.
99
What wavelength of light does PSI absorb maximally?
700nm
## Footnote
PSI is specifically tuned to absorb light at this wavelength.
100
What wavelength of light does PSII absorb maximally?
680nm
## Footnote
PSII is optimized to absorb light at this wavelength.
101
What are the two components that electrons are passed through after plastiquinone?
Cytochrome and plastocyanin
102
What happens when an electron in Photosystem I (PSI) gets excited by light?
It has two possible paths: Linear Electron Flow or Cyclic Electron Flow
## Footnote
These paths determine the type of energy carrier produced.
103
What is the outcome of Linear Electron Flow in PSI?
The electron helps convert NADP⁺ into NADPH
## Footnote
NADPH is essential for making sugars.
104
What is the outcome of Cyclic Electron Flow in PSI?
The electron goes back to the cytochrome b6f complex and helps make more ATP instead of NADPH
## Footnote
This process increases ATP production without producing NADPH.
105
Fill in the blank: In Linear Electron Flow, the electron helps convert _______ into NADPH.
NADP⁺
106
True or False: Cyclic Electron Flow produces NADPH.
False
107
What system is involved in photosynthesis?
A proton gradient system
108
Where do protons accumulate during photosynthesis?
Inside the thylakoid lumen
109
What type of gradient is established across the thylakoid membrane?
An electrical gradient
110
Why is the proton and electrical gradient crucial?
It creates ideal conditions for energy production
111
What process is driven by the energy produced in photosynthesis?
ATP synthesis via ATP synthase
112
Fill in the blank: The proton gradient in photosynthesis is generated by _______.
photosynthesis
113
True or False: The thylakoid membrane establishes both a proton and electrical gradient.
True
114
What is the role of ATP synthase in photosynthesis?
Drives ATP synthesis
115
What is oxidized in the z scheme?
2 H2O
116
What is produced as a result of the oxidation of 2 H2O in the z scheme?
O2
117
How many NADP+ are reduced in the z scheme?
2 NADP+
118
What are the reduced forms of NADP+ in the z scheme?
2 NADPH
119
Fill in the blank: In the z scheme, 2 H2O are oxidized to _______.
O2
120
True or False: The z scheme involves the reduction of NADP+.
True
121
What does Mitchell's Chemiosmosis Theory explain?
Conversion of energy from electron transport via formation of a transmembrane electrochemical gradient
## Footnote
This theory is fundamental in understanding how ATP is produced in cellular respiration and photosynthesis.
122
What is required for the generation of the proton motive force in chemiosmosis?
e (H*) transfer across a 'coupling' membrane
## Footnote
This transfer is essential for generating the proton motive force.
123
What does Дин represent in the context of chemiosmosis?
Дин = Д¥+ ДрН (also called the 'proton motive force')
## Footnote
Дин is crucial for driving the synthesis of ATP.
124
What is the role of Дин in ATP synthesis?
Drives protons through ATP synthase (H+-ATPase) to make ATP
## Footnote
This process is vital for energy conversion in cells.
125
Fill in the blank: Chemiosmosis involves the generation of a _______ across a membrane.
transmembrane electrochemical gradient
## Footnote
This gradient is critical for ATP synthesis.
126
True or False: ATP is produced directly from the electron transport chain.
False
## Footnote
ATP production occurs through the process of chemiosmosis, not directly from the electron transport chain.
127
What is the function of photosynthetic reaction centers in chemiosmosis?
They facilitate the transfer of electrons
## Footnote
This transfer is essential for establishing the electrochemical gradient.
128
What is photophosphorylation?
Synthesis of ATP which is dependent upon light energy
## Footnote
Photophosphorylation occurs in the chloroplasts during photosynthesis.
129
What are the two major particles of chloroplast ATP synthase?
* CFo
* CF1
## Footnote
These particles play crucial roles in the process of ATP synthesis.
130
What is the function of CFo in chloroplast ATP synthase?
Spans the membrane and forms a pore for H+
## Footnote
This allows protons to flow through, which is essential for ATP synthesis.
131
What does CF1 do in chloroplast ATP synthase?
Protrudes into the stroma and catalyzes ATP synthesis from ADP and Pi
## Footnote
This is a critical step in the energy production process.
132
What are the main components of ATPase?
Anchor, stator, and head group
## Footnote
The head group consists of six alpha and six beta parts.
133
What does the head group of ATPase consist of?
Alpha and beta parts
## Footnote
Specifically, six alpha and six beta parts.
134
What function does the head group serve in ATPase?
Allows the rotator to rotate and causes conformational changes
## Footnote
These changes drive the synthesis of ATP.
135
What is the role of ATP synthase?
It is a rotator that helps synthesize ATP
## Footnote
It uses changes in position and conformational changes to bring ADP and inorganic phosphate together.
136
How does ATP synthase bring ADP and inorganic phosphate together?
By utilizing movement and conformational changes
## Footnote
The movement of proteins across the rotator causes this action.
137
Fill in the blank: The head group of ATPase is composed of _______ and _______.
alpha, beta
138
True or False: The head group of ATPase is responsible for driving the synthesis of ADP.
False
## Footnote
The head group drives the synthesis of ATP, not ADP.
139
What is produced from the proton gradient in cyclic electron flow?
2 ATP
## Footnote
This ATP is generated for every 4 electrons transferred to 2 NADPH.
140
How many NADPH and ATP are required for each CO2 reduced to (CH20) in carbohydrate synthesis?
2 NADPH and 3 ATP
## Footnote
This highlights the energy requirements for carbohydrate synthesis.
141
What does cyclic electron transport yield?
ATP but not NADPH
## Footnote
This is important for balancing the energy needs in photosynthesis.
142
What role does ferredoxin play in cyclic electron flow?
Donates electrons back to the PQ pool via a specialized cytochrome
## Footnote
This is an alternative pathway that does not involve NADP+.
143
What does cyclic flow increase in terms of energy production?
Protonmotive force and ATP production
## Footnote
However, it does not produce NADP+.
