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Biology HL > 8.2 Cell Respiration > Flashcards

8.2 Cell Respiration Flashcards

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1
Q

8.2 Describe glycolysis (4 steps)

A
  1. Phosphorylation
    - glucose (hexose sugar) phosphorylated by 2 ATP molecules which forms hexose biphosphate
  2. Lysis
    - hexose biphosphate (6C) is split into 2 triose phosphate (2C)
  3. Oxidation
    - H atoms removed from each 3C sugars to reduce NAD+ -> NADH (+H+) (oxidation), results in 2 molecules of NADH to be produces
  4. ATP formation
    - some energy released from sugar intermediates (pyruvate) used to directly synthesis ATP
    - called substrate level phosphorylation
    - 4 molecules of ATP generated (2 per 3C sugar)
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2
Q

8.2 is the net gain of glycolysis?

A

NADH (+H+) = 2
ATP = 2 (4-2)
Pyruvate = 2

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3
Q

8.2 Where does glycolysis occur?

A

In the cytoplasm
(NO OXYGEN REQUIRED)

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4
Q

8.2 What does anaerobic pathway do?

A

Allows glycolysis to continue even in the absence of oxygen for the generation of NAD+
(Like a reset)

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5
Q

8.2 what does glycolysis involve? (simple)

A

breakdown of glucose into pyruvate (2) with small net gain of ATP

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6
Q

8.2 where does glycolysis occur? and what does it not require?

A
  • cytosol
    -does not require oxygen
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7
Q

8.2 depending on the availability of oxygen, what may pyruvate be subjected to? (2)

A
  • aerobic respiration in the presence of oxygen and results in further production of ATP
  • anaerobic respiration (fermentation) occurs in absence of oxygen and no further ATP is produced
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8
Q

8.2 what occurs after glycolysis if oxygen is available? (4)

A
  • pyruvate is transported to the mitochondria for further breakdown (complete oxidation)
  • further oxidation generates large numbers of reduced hydrogen carriers (NADH + H^+ and FADH2)
  • the reduced H carriers can release their stored energy to synthesise more ATP
  • aerobic respiration involves 3 additional processes (link reaction, krebs cycle and electron transport chain)
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9
Q

8.2 what occurs if oxygen is not present? (2)

A
  • pyruvate is not broken down further and no more ATP is produced (incomplete oxidation)
  • pyruvate remains in cytosol and converted into lactic acid / ethanol + CO2
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10
Q

8.2 what are features of anaerobic respiration? (2)

A
  • the conversion is reversible
  • necessary to ensure glycolysis can continue to produce small quantities of ATP
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11
Q

8.2 what is the first stage of aerobic respiration?

A

link reaction

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12
Q

8.2 where is the pyruvate transported in the link reaction? and how? (2)

A

-from cytosol to the mitochondrial matrix
-by carrier proteins on on mitochondrial membrane

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13
Q

8.2 what are the processes of the link reaction? (3)

A
  1. pyruvate is decarboxylated forming CO2 (3C compound -> 2C compound)
  2. 2C compound forms an acetyl group when oxidised & H is removed (reduction of NAD -> NADH + H+)
  3. acetyl compound combines with coenzyme A to form acetyl CoA
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14
Q

8.2 what are the products of link reaction?

A

ATP = 0
NADH (+H+) = 2
Acetyl CoA = 2
CO2 = 2

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15
Q

8.2 what is the overall process of link reaction called?

A

oxidative carboxylation

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16
Q

8.2 Where does the kerbs cycle occur?

A

Kn the matrix of the mitochondria

17
Q

8.2 What are the processes of the kerbs cycle? (5)

A
  1. Acetyl CoA transfers acetyl group to 4C compound to form a 6C compound
    -> coenzyme is released back to link reaction to be used again
  2. Over series of reactions 6C compound is broken down to reform the original 4C compound
    - 2 carbon are released via decarboxylation to from 2CO2
    - Multiple oxidation reactions occur resulting in reduction of hydrogen carriers
    (3x NADH + H+ ; 1 x FADH2)
    - 1 molecules of ATP produced through substrate level phosphorylation
18
Q

What are the products of the 2 cycles of Krebs cycle (per glucose molecule)?

A

ATP = 2
NADH = 6
FADH2 = 2
CO2 = 4

19
Q

Where does oxidative phosphorylation?

A

Occurs in the mitochondrial membrane

20
Q

What is the overall process of oxidative phosphorylation?

A

Reduces the H-carrier coenzyme to release energy for the electron transport chain

21
Q

What are the three steps of oxidative phosphorylation?

A
  1. Proton pump create electrochemical gradient
  2. ATP synthase uses diffusion of protons (chemiosmosis) to synthesis ATP
  3. Oxygen accepts electrons and protons to form water
22
Q

What are the processes of the electron transport chain?(7)

A
  1. NADH is oxidised (to NADH+) and protein carriers accepts the elections found in inner mitochondrial membrane)
  2. Electrons pass through the electron transport chain -> transferring energy in a series of REDOX reactions and heat is released
  3. Energy from movement of electrons carries the movement of H+ ions to be pumped (active transport) through the membrane into the intermembrane space
  4. Chemiosmotic gradient (protons / H+) is created
  5. Hydrogen ions return to the matrix down the concentration gradient by facilitated diffusion though ATP synthase (embedded in inner membrane)
  6. Movement of H+ causes ATP to produce ADP+Pi -> ATP
  7. O2 is the final acceptor of electrons (reduced) to H2O (to prevent blockage) maintaining chemiosmotic gradient
23
Q

What does the outermembrane of the mitochondria do?

A

Contains transport proteins that enable the shuttling of pyruvate from the cytosol

24
Q

What does the inner membrane of the mitochondria do?

A

Contains the electron transport chain and ATP synthase (used for oxidative phosphorylation)

25
Q

What does the Cristae of the mitochondria do?

A

The inner membrane is arranged into fold (cristae) that increase the SA:Vol ration (more surface)

26
Q

What does the intermembrane space of the mitochondria do?

A

Small space between membrane maximises hydrogen gradient upon proton accumulation

27
Q

What does the matrix of the mitochondria do?

A

Central cavity that contains appropriate enzymes and a suitable pH for the kerbs cycle to occur

28
Q

What is electron tomography?

A

Technique where 3D internal structures of a sample can be modelled

29
Q

How does electron tomography work?(3 steps)

A
  1. Samples are repeatedly imaged using a transmission electron microscope
  2. Following each image, the sample is tilted to a different angle relative to the electron beam
  3. Images then compiled and used to computer reconstruct a £D representation (tomogram)
30
Q

How must the samples for tomography have to be prepared?

A

By fixing and dehydrating or freezing (cryogenics)

31
Q

What featured of active mitochondria have been identified thanks to tomography?

A
  1. Cristal are contentious with internal mitochondrial membrane
  2. Inter membrane space is of consistant width throughout entire mitchondrion
  3. Relative shape, position and volume of cristae can change in active mitochondria

Biology HL (14 decks)

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