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Biology > Energy Generation in Mitochondria and Chloroplasts > Flashcards

Energy Generation in Mitochondria and Chloroplasts Flashcards

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1
Q

What is so special about the mitochondria?

A
  • membrane bound organelle
  • produce most of the cell’s ATP
    -can form long tubular network
    -can adjust their location, shape, and number to suit cell need
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2
Q

What are the compartments of a mitochondria?

A

Matrix, Inner Membrane, Outer Membrane, Inter membrane space

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3
Q

What is the matrix of the mitochondria?

A

An area that contains highly concentrated mixture of hundreds of enzymes, used for the oxidation of pyruvate and fatty acids for the citric acid cycle; where citric acid cycle is located

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4
Q

What is the inner membrane of the mitochondria?

A

Area that contains the protein that carry out oxidative phosphorylation, including the electron transport chain and the ATP synthase that makes ATP. There are series of folding called cristae, increasing the surface area of the membrane.

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5
Q

What are cristae?

A

Foldings in the inner membrane of the mitochondria

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6
Q

What is the outer membrane of the mitochondria?

A

The outer site of the mitochondria that contains many transport protein called porin, making all molecules 5000 daltons or less permeable.

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7
Q

What is the permeability difference between the outer membrane and the inner membrane?

A

Inner membrane is very impermeable while outer membrane is permeable to molecules 5000 daltons or less

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8
Q

What is the intermembrane space?

A

The site between the outer and inner membrane of the mitochondria. This space contains enzymes that use the ATP passing out the matrix to phosphorylate other nucleotides.

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9
Q

Where is the electron transport chain located?

A

Inner membrane of the mitochondria

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10
Q

Where does the citric acid cycle take place in the mitochondria?

A

The mitochondria’s matrix

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11
Q

What does it mean for an atom to become oxidized?

A

Atom donating an electron

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12
Q

What does it mean for an atom to become reduced?

A

Atom accepting an electron

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13
Q

What gets pumped out everytime an electron travels through an ETC protein complex?

A

A proton

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14
Q

What is a redox potential?

A

Energy released by electron transfer

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15
Q

What does a redox reaction depend on to proceed?

A

Delta G being negative

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16
Q

What is the trend between redox potential and electron affinity?

A

Negative redox potential have low electron affinity

Positive redox potential have high electron affinity. Electrons will flow to more positive redox potential.

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17
Q

What can we say about the redox potential of the ETC as the electron only proceed one direction?

A

The redox potential gets more positive in the direction the electron travels

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18
Q

What does each of the three respiratory enzyme complex have to transfer electrons?

A

Metal tightly bound to protein

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19
Q

How does electron use the metal to move along the electron transport chain?

A

Electron skip from one embedded metal ion to another ion that has an affinity for electrons.

  • Redox potential becomes more positive as electron moves, thus there is a greater affinity in the metal ions.
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20
Q

What type of metal does NADH dehydrogenase have?

A

Iron-sulfur centers

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21
Q

Because the iron-sulfur center have a low positive redox potential, where might it be located on the ETC?

A

Early part of the chain

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22
Q

What does ubiquinone do?

A

picks up electrons from the NADH dehydrogenase complex and delivers them to the cytochrome c reductase complex

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23
Q

What is ubiquinone?

A

Small hydrophobic molecule that contribute to electron movement from the NADH dehydrogenase complex to the cytochrome c reductase complex

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24
Q

What type of metal does cytochrome b-c1 complex have?

A

Heme (iron atoms)

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25
Q

What is cytochrome c?

A

A membrane protein that is a mobile electron carrier

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26
Q

What does cytochrome c do?

A

Transfer electron from the cytochrome b-c1 complex to the cytochrome c oxidase complex.

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27
Q

What type of metal does cytochrome c oxidase have?

A

Heme and Copper

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28
Q

What does cytochrome c oxidase do?

A
  • Remove electron from cytochrome c (electron carrier) and combines the electron to an oxygen molecule to produce water.
  • catalyze the reduction of O2 to form water
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29
Q

What does cytochrome c oxidase do to catalyze the reduction of oxygen?

A

Take four electrons by cytochrome c and four protons extracted from the aqueous environment and add it to an oxygen molecule, forming 2 water molecules

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30
Q

What happens to the energy that is released from the passage of electron?

A

It is harnessed to to pump protons across the mitochondrial inner membrane

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31
Q

Describe the flow of electrons

A

Electrons flow from a unit that has a lower affinity to a unit that has a higher affinity for electrons.

Ex: NADH has a lower affinity so it donates its electron to NADH dehydrogenase complex which has a higher affinity , regenerating NAD+ at the same time.

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32
Q

What does proton pumping produce?

A

Electrochemical force

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33
Q

What use electrochemical force produced by proton pumping to produce ATP

A

ATP synthase

34
Q

How does ATP synthase produce ATP?

A

It acts like a motor by using the electrochemical gradient to convert the energy of proton to chemical bond energy in ATP

35
Q

What does proton electrochemical gradient contribute to

A

ATP synthesis - chemiosmotic coupling
Coupled Transport

36
Q

What happens if the proton gradient dissipates?

A

No ATP will produce

37
Q

What is a chloroplast?

A

Organelle in plants that captures light energy to produce organic molecule

38
Q

What are the three layers of the chloroplast?

A

Inner membrane, Outer membrane, thylakoid membrane

39
Q

What is the differences between the organization of mitochondria and chloroplast?

A

The inner membrane in the chloroplast does not produce energy, like the mitochondria. Instead, energy is produced in the thylakoid membrane in chloroplasts.

40
Q

What is the thylakoid?

A

flattened sacs inside a chloroplast where the light reaction takes place

41
Q

What is a granum?

A

Stacks of thylakoid

42
Q

What are the two stages of photosynthesis?

A
  1. Light Reaction
  2. Light Independent Reaction
43
Q

What happens in the light dependent reaction stage?

A

Energy from sunlight is used to produce ATP and NADPH

44
Q

What happens in the light independent reaction stage?

A

ATP and NADPH are consume to synthesize sugar

45
Q

What stage in the mitochondria does the light dependent reaction resemble?

A

Oxidative phosphorylation stage

46
Q

Describe the process of the light dependent reaction

A

The electron-transport chain in the thylakoid membrane harnesses the energy of electron transport to pump protons into the thylakoid space; the resulting proton gradient then drives the synthesis of ATP
by ATP synthase.

47
Q

What is the differences between the photosynthesis and the oxidative phosphorylation stage in the mitochondria?

A

Chlorophyll donates the high energy electrons, who’s energy comes from the sun. In the mitochondria, NADH donates the electron to become NAD+.

Another difference is electrons are donated to NADP+ to produce NADPH at the end of the electron transport chain. In the mitochondria, electron is donated to oxygen to produce water.

48
Q

What does the chlorophyll do?

A

Absorbs photons which excites the electron, raising its orbital to a higher energy

49
Q

What happens to both the electrons and chlorophyll when exposed to sunlight?

A

It excites the electron causing the chlorophyll to be excited. This cause the chlorophyll to release the excess energy, allowing it to return to its more stable, unexcited state.

50
Q

What does chlorophyll need in order to prevent all its released energy as heat?

A
51
Q

What is the structure of chlorophyll?

A

A prophyrin ring with a magnesium atom at the center, connected to a long hydrophobic tail.

52
Q

What does the structure of chlorophyll contribute to?

A

The long hydrophobic tail helps hold the chlorophyll in the thylakoid membrane and the porphyrin ring to transfer electrons down the electron transport chain to drive the photosynthetic process.

53
Q

How does chlorophyll prevent all of its released energy to be released as heat?

A

It has protein complex (photosystems) that converts that light energy into chemical energy

54
Q

What happens in the antenna complexes of photosystem?

A

Energy jumps randomly from one chlorophyll molecule to the next. However, at some point, wandering energy will encounter the “special pair”.

55
Q

What is the special pair of chloroplast?

A

Chlorophyll dimer that traps energy once energy bounce its way from the antenna complex to the special pair and deliver the electrons of the electron transport chain.

56
Q

Where is the chlorophyll special pair located?

A

Reaction center

57
Q

What happens in the reaction center?

A

High energy electron is transferred from the chlorophyll special pair to a carrier that becomes part of an electron transport chain

58
Q

What happens to the chlorophyll special pair after it donates its electron?

A

The special pair becomes positively charged and the electron carrier that accepts the electron becomes negatively charged.

59
Q

What does the chlorophyll special pair pass its electron to?

A

A electron carrier called plastoquinone

60
Q

What does photosystem II do?

A

Feeds electron to a photosynthetic proton pump, leading to ATP generation from ATP synthase.

61
Q

Describe the movement from photosystem II to photosystem I

A
  • Photosystem II pass the electrons to an electron carrier: plastoquinone.

-Plastoquinone pass the electrons to a proton pump: cytochrome b6 f complex

-Cytochrome b6 f complex pass electron to photosystem I

62
Q

What does photosystem I do?

A

transfer high energy electrons to an enzyme that produce NADPH

63
Q

Describe the movement from which a electron arrives to photosystem I to how it’s used to regenerate NADPH

A

-Photosystem I receives electron from cytochrome b6 f complex

-When light energy is captured by photosystem I, photosystem I pass the electron to electron carrier: ferredoxin

-Ferredoxin carries the electron to ferredoxin-NADP+ reductase complex

-Ferredoxin-NADP+ reductase catalyze the production of NADPH by accepting the electron from ferredoxin

64
Q

If a mobile electron carrier removes an electron from the reaction center, this would cause the chlorophyll special pair to become positively charged. How would the missing electrons be replaced?

A

On top of photosystem II, there is a manganese protein complex (water splitting enzyme) that removes electron from water. The water splitting enzymes holds two water molecules, in which 4 electrons are extracted, releasing oxygen we breath into the atmosphere.

65
Q

What is the differences between the mitochondria ETC and the chloroplast ETC?

A

In mitochondria, NAD+ is regenerated from the extraction of electron from NADH and oxygen is the terminal electron accepter. Water is produced.

In chloroplast, oxygen is regenerated from the extraction of electron from water and NADP+ is the terminal electron acceptor. NADPH is produced.

66
Q

What happens to the NADPH and ATP generated in the chloroplast?

A

It is used for carbon fixation (Calvin cycle)

67
Q

What is carbon fixation?

A

The second stage of photosynthesis where CO2 and water are used for the production of sugar

68
Q

What makes the calvin stage light independent?

A

Reactions take place in the chloroplast stroma and can continue in the dark until all ATP and NADPH is exhausted

69
Q

Describe the process of carbon fixation

A
  1. Carbon Fixation
    - 3 CO2 combines with 3 Rubisco to make 6 3-phosphoglycerate.
  2. Sugar Formation
    - 6 glyceraldehyde 3-phosphate are formed by using 6 ATP and 6 NADPH to form sugar from the 3-phosphoglycerate.
  3. Regeneration of Ribulose 1,5-Bisphosphate (Rubisco)
    - 5 of the 6 glyceraldehyde 3-phosphate and 3 ATP are used to regenerate 3 Rubisco that is used for the next cycle
70
Q

If carbon fixation is energetically expensive and unfavorable, how is it able to be carried out?

A

the fixation of CO2 catalyzed by Rubisco is energetically favorable reaction because a continuous supply of energy-rich ribulose 1,5-bisphosphate is fed into the reaction.

71
Q

If Ribulose 1,5-bisphosphate is constantly used for carbon fixation, how is it regenerated?

A

By the ATP and NADPH produced by the photosynthetic light reaction

72
Q

What is the net results of the calvin cycle?

A

For every 3 molecules of CO2, 9 ATP and 6 NADPH,

  • 1 molecule of glyceraldehyde 3-phosphate is produced
73
Q

How does the chloroplast and mitochondria work together to supply plant cell?

A

They supply plant cell with metabolites and ATP

74
Q

What type of catabolic process did organism used before the presense of oxygen?

A

Fermentation

75
Q

What was the result of organism doing fermentation breakdown?

A

The pH of the environment lowered. When cells perform fermentation, this caused cell to pump out H+ lowering the pH of the environment.

76
Q

If the pH of the environment becomes too acidic as a result of cell fermentation, how did cells overcome this?

A

Some cells survived, which favored the cells that evolved transmembrane proteins that
could pump H+ out of the cytosol, preventing the cell interior from becoming too acidic.

77
Q

What happened to the cell that evolved transmembrane protein to maintain their internal pH from the acidic environment?

A

They evolved to use the movement of electrons between molecules as a source of energy for pumping H+ across the plasma membrane. Eventually their H+ pumping ETC system would become efficient enough that it could generate steep gradient and couple those with energy production.

78
Q

What was the cause of the increased concentration of oxygen?

A

Early photosynthetic bacteria evolving to have a water splitting enzymes release oxygen into the atmosphere.

79
Q

What was the result of the increased concentration of oxygen?

A

Aerobic organism emerged and eventually some organism came to rely entirely on cell respiration

80
Q

What are some evidence that proved that mitochondria and chloroplast were once its own organism

A
  1. Both have their own DNA
  2. Genetic similarity between mitochondrial gene and bacteria

It’s thought that
Mitochondria were ancient bacteria engulfed by ancestral eukaryotic cell

Chloroplast were ancient photosynthetic bacteria engulfed by eukaryotic cell

Biology (20 decks)

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