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Bio 120 > Chapter 7 > Flashcards

Chapter 7 Flashcards

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Biology 101 flashcards
1
Q

What is the Photosynthesis reaction?

A

6 CO2 + 6 H2O –(light energy)–>C6H12O6 (glucose) + 6O2

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2
Q

What is highly evolved to maximize the efficiency of photosynthesis?

A

The structure of leaves and chloroplasts

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3
Q

What allows for the gas exchange in photosynthesis?

A

Between the atmosphere and inside the leaf

*The air spaces in leaves

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4
Q

What maximizes membrane surface area in photosynthesis?

A

Thylakoid membranes

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5
Q

Stomata

A

Through which O2 & CO2 are exchanged with the atmosphere

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6
Q

Thylakoids

A
  • Light absorption by chlorophylls & carotenoids
  • electron transport
  • STP synthesis by ATP synthase
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7
Q

What type of process is photosynthesis?

A

It is a redox process

- Electrons are taken from one reactant and moved to another

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8
Q

In the photosynthesis reaction, what is the reduction agent? Oxydation agent?

A

Reduction (lose e) = 6 CO2

Oxidation (gain e) = 12 H2O

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9
Q

What are the two parts to photosynthesis? What do they do?

A

1) The light reactions: Collect light energy, Oxidize H20, and stores energy as ATP and NADPH
2) Carbon fixation (Calvin cycle): Use ATP and NADPH to reduce CO2

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10
Q

Light reactions (4 things)

A

1) H2O enters chloroplast, and collects energy from sunlight
2) The light reaction has ADP + Pi and NADP+ that come in
3) It makes ATP and NADPH
4) O2 leaves the chloroplasts

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11
Q 
Calvin Cycle (Carbon Fixation)
4 things
A

1) CO2 enters chloroplast
2) The Calvin cycle has ATP and NADPH that come in
3) It makes ADP + Pi and NADP+
4) Sugars (carbohydrates) leave the chloroplasts

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12
Q

Stroma

A

The space around the thylakoids

- The calvin cycle

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13
Q

Light:

What type and color are the shortest, most energetic wavelengths?

A

Gamma rays

Purple/ Blue

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14
Q

Light:

What type and color are the longest, lowest enegy wavelengths?

A

Radio waves

Red

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15
Q

Why are plants green?

A

The color green is due to the chlorophyll absorbing red, blue, etc light… and reflecting and transmitting green light

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16
Q

What are the main pigments absorbing light for photosynthesis? are they polar or nonpolar?

A

Chlorophylls and Carotenoids are the main pigments absorbing light for photosynthesis
They are quite nonpolar

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17
Q

What is always bound to proteins?

A

Chlorophyll

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18
Q

Which is only present in the Thylakoid membrane? Chlorophylls and Carotenoids?

A

Chlorophylls

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19
Q

What does the hydrophobic tail allow the chlorophyll to do?

A

Its hydrophobic tail allows it to interact with proteins in the thylakoid membrane

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20
Q

What did Joseph Priestly discover in 1772?

A
  • He discovered Oxygen

- Found that plants could purify air

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21
Q

What did Jan Ingen-Housz discover in 1781?

A
  • He discovered that only green plants could purify the air but they have to be in the light
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22
Q

What did Julius Mayer discover in 1845?

A
  • He discovered that energy from the sun is converted by photosynthesis into a chemical form
  • Found that plants are only green when they grown in the light
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23
Q

What do Aerotactic bacteria move towards?

A

They move towards the oxygen

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24
Q

Theodor Engelmann 1883:

What wavelengths of light are the most important for photosynthesis?

A

Chlorophyll is best produce in Red & Blue waves

- which closely matches the absorption spectrum of leaf pigments

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25
Q

What type of light is always at a longer wavelength?

A

Light give off as Fluorescence is always at a longer wavelength, and some energy is lost in the transfer process
- 2nd law of thermodynamics

26
Q

Explain what happens in the first two parts of a light reaction

A

1) A photon passes through the Photosystem II
- 2 H2O comes in, and produces 4 H+ + O2
- passes 4e- through the Photosystem II to the electron transport chain
* Oxidizes H20 and taking its electrons*
2) The electrons pass through the Cytochrome complex, and through the Plastocyanin transporter protein

27
Q

Explain what happens in the middle of a light reaction

A

3) A photon of light passes through the Photosystem I
- The electrons from the Plastocyanin transporter protein also pass through the Photosystem I
4) The electrons then pass through the Ferredoxin transporter protein
5) Then in NADP+ reductase:
- 2H+ + NADP+ come in, and produces NADPH

28
Q

Explain what is the last steps of the light reaction

A

6) The ATP made through the ATP Synthase combine with the NADPH made by the NADP+ reductase which form the Calvin cycle

29
Q

What does the light-harvesting system do?

A

It helps the reaction centre by absorbing lots and lots of light energy

30
Q

The Electron Transport Chain-Pt I (Photosystem II)

__ photons of light will transfer __ electrons from ____ molecules to give __ and ______

A

4 photons of light will transfer 4 electrons from 2 H2O molecules to give O2 and 4 electrons (e-)

31
Q

The Electron Transport Chain-Pt I (Photosystem II)
The __ are moved to the next complex using ___ (__________)
This also moves ____ across the membrane into the ____________

A

The e- are moved to the next complex using PQ (a mobile e- carrier).
This also moves H+ ions across the membrane into the Thylakoid Lumen

32
Q

The Electron Transport Chain-Pt II (Cytochrome Complex)

  • _____ the mobile e- carrier passes its e- to the next ____________
  • The e- continues through the _______________ and H+ ions are actively transported into the ___________, building up the proton motive force
A
  • PQH2 the mobile e- carrier passes its e- to the next protein complex
  • The e- continues through the electron transport chain and H+ ions are actively transported into the Thylakoid Lumen, building up the proton motive force
33
Q

The Electron Transport Chain-Pt III (Photosystem I)
When the e- reaches ___________ it has very little energy left. ____ and its __________, absorb light energy and re-excite the ___

A

When the e- reaches Photosystem I it has very little energy left. PSI and its light harvesting complex, absorb light energy and re-excite the e-

34
Q

The Electron Transport Chain-Pt III (Photosystem I)

  • The re-excited e- is then used to make ____ by the _____ _______ ______
  • The cell now has a mobile source of high energy electrons that can be used to convert _____ into ________
A
  • The re-excited e- is then used to make NADPH by the NADP reductase enzyme
  • The cell now has a mobile source of high energy electrons that can be used to convert CO2 into carbohydrates
35
Q

Which photosystem excites the electrons and makes NADPH? Which one uses oxygen?

A

Photosystem I

Photosystem II

36
Q

The loss of energy is coupled to what?

A

The loss of energy is coupled to the movement of H+ ions

37
Q

After the 3 parts of the electron transport chain, what happens?

A

Chemiosmosis
The build up of H+ ions in the thylakoid lumen can now be used by an ATP synthase to convert ADP to ATP
- It works just like in Mitochondria but here it is called Photophosphorylation

38
Q

_____ uses light energy to oxidize ____ creating __, it then passes the electrons to the ______________

A

PSII uses light energy to oxidize H2O creating O2, it then passes the electrons to the electron transport chain

39
Q

The _____ moves electrons, _____ energy, while pumping H+ ions into the ___________

A

The ETC moves electrons, losing energy, while pumping H+ ions into the thyakoid lumen (generating a pmf)

40
Q

____then re-excites the electrons giving them enough energy to reduce ______ into _______

A

PSI then re-excites the electrons giving them enough energy to reduce NADP+ into NADPH

41
Q

The ________ uses the potential energy of the ___ to generate _____

A

The ATP synthase uses the potential energy of the pmf to generate ATP

42
Q

At the end, the cell has ______ (_____ energy electrons) and ______ to use for making __________

A

At the end, the cell has NADPH (high energy electrons) and ATP to use for making carbohydrates

43
Q

Light Reactions occur in the _____________

Dark Reactions occur in the ________________

A

Light Reactions occur in the Thylakoid Membrane

Dark Reactions occur in the Stroma of the chloroplast

44
Q

How can we test where the atoms go in photosynthesis?

A

Using RadioIsotopes such as (18) oxygen

45
Q

Radioisotopes are generally atoms with _________.

This makes the atom ______________________?

A

Radioisotopes are generally atoms with extra neutrons.
This makes the atom unstable and it tends to decay or breakdown giving off particles, then we can detect these particles and thus the presence of Radioisotopes

46
Q

What is (18)O ?

A

It is a stable isotope because it does not breakdown

47
Q

(18) O composes ____ of natural O, but can be enriched to higher levels

A

0.2%

48
Q

How could we see if the O2 produced by photosynthesis comes from CO2? What is the result

A

If we would feed some C(18)O2 to a plant, shine light on the plant, then analyze the O2 produced
- We would see that it doesnt contain radioactive oxygen

49
Q

How can we be sure that the O2 produced by photosynthesis does not come from CO2?

A

By performing a 2nd experiment, the reverse

  • Water the plant with H2 (18)O then analyze the O2 produced
  • We would see the radioactive oxygen produced by the plant
50
Q

What would these experiments tell us? (4 things)

A

1) C of CO2 ends up in carbohydrate
2) H+ from H2O broken by PSII makes ATP
3) O2 released from H2O by PSII
4) H2O from Dehydration reactions in the Calvin cycle

51
Q

____ diffuses into the _____ of the chloroplast where enzymes use it to make __________

A

CO2 diffuses into the stroma of the chloroplast where enzymes use it to make carbohydrates

52
Q

Carbon Fixation Reactions (Calvin cycle):

_____ from the atmosphere is reduced and energized using _____ and _____ to give simple __________

A

CO2 from the atmosphere is reduced and energized using NADPH and ATP to give simple carbohydrates (Triose Phosphate)

53
Q

What was the goal of the research team performing the Calvin’s experimental set up? What was the experiment

A

To identify thec arbon compounds produced by photosynthesis
- They grew green algae, fed them (14)CO2 (-radioactive) , and rapidly killed the cells
= which caused the enzymes to stop working

54
Q

Steps of the Chlorella experiment

A

1) Cells were rapidly killed in hot ethanol and carbohydrates were extracted
2) Carbohydrates were separated by chromatography (wet then dry)
3) The chromatography sheet exposed to x-ray film to detect the (14)C = autoradiography
4) Radioactive spots could then be identified by comparison to know chemicals

55
Q

What is the first product of Carbon fixation?

A

3-phosphglycerate

56
Q

What are the 3 phases of the Calvin Cycle?

A

1) Carbon fixation =6 CO2 is incorporated into an organic molecule via rubisco
2) Reduction and carbohydrate production = 12 ATP are used as a source of energy, and 12 NADPH donates high energy electrons
3) Two G3P are used to make Glucose and sugars
4) Regeneration of RuBP= 10 G3P are needed to regenerate 6RuBP via several enzymes. ATP is required for RuBP regeneration
* *RuBP= 6 Ribulose bisphosphate**

57
Q

What is the most abundant enzyme on earth?

A

Ribulose 1,5-bisphosphate carboxylase/oxygenase

  • It accounts for about 40% of leaf soluble protein in all plants
  • It fixes CO2
58
Q

CO2 is fixed by _______

A

Rubisco

59
Q

The initial product of Rubisco, _________________, is reduced using the electrons from _______ and energy from _____

A

The initial product of Rubisco, 3-Phosphoglycerate, is reduced using the electrons from NADPH and energy from ATP

60
Q

A ______(simple carbohydrate) is produced and then the Calvin Cycle regenerates the starting compound _______________

A

A triose phosphate(simple carbohydrate) is produced and then the Calvin Cycle regenerates the starting compound (Ribulose-1,5-bisphosphate)

61
Q

The use of ____ and ______ during carbon fixation, regenerates ___ and____ for the light reactions

A

The use of ATP and NADPH during carbon fixation, regenerates ADP and NADP+ for the light reactions

62
Q

What are the 3 main phases of the Calvin cycle?

A

1) Carbon fixation
2) Reduction and carbohydrate production
3) Regeneration of RuBP

Bio 120 (12 decks)

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