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Biology > Respiration > Flashcards

Respiration Flashcards

1
Q

Respiration Equation

A

Glucose + Oxygen -> Carbon Dioxide + Water + Energy

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2
Q

Why is glucose NOT used directly?

A
  • glucose broken down in many steps. involving many specific enzymes
    if glucose is broken down in one step:
  • too much heat energy released causing enzymes to denature
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3
Q

How is mitochondria adapted to its function?

A
  • Small organelle= large SA/vol ratio
  • Short diffusion path for O2
  • many cristae increase SA for ETC/ ATP synthase
  • aqueous matrix (soluble enzymes)
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4
Q

Explain advantage of many cristae

A
  • larger SA for electron carrier system
  • provides more ATP for muscle contraction
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5
Q

What are the 4 stages of aerobic respiration?

A
  1. glycolysis (cytoplasm)
  2. link reaction (matrix of mitochondria)
  3. krebs cycle (matrix of mitochondria)
  4. electron transport chain (inner mitochondrial membranes)
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6
Q

Two ways that ATP can be generated

A
  • Substrate-level phosphorylation- ATP generated directly through energy released via respiration reactions. This occurs in Glycolysis and the Krebs cycle
  • Oxidative phosphorylation – ATP generated from the chemical energy released when a reduced hydrogen carrier or coenzyme (NADH2 or FADH2) has been oxidised at the Electron Transfer Chain.
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7
Q

Glycolysis

A
  • Glucose (6C) activated by phosphorylation requires hydrolysis of 2 ATP to 2ADP to provide 2 phosphates
  • Glucose phosphate then splits into 2 x triose phosphate
  • TP (3C) oxidised to pyruvate (3C) and involves loss of H (via dehydrogenase enzyme) reduces hydrogen carrier NAD to NADH2
  • ATP produced via substrate level phosphorylation

Produces:
2 net ATP
2 NADH
2 pyruvate ( leave mitochondria by AT)

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8
Q

The Link reaction

A
  • Pyruvate is oxidised to acetate
  • Hydrogen removed to form reduced NAD
  • CO2 is lost via decarboxylation
  • NO ATP is produced
  • Acetyl co A produced
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9
Q

The Krebs cycle

A
  • 2C Acetyl co A combines with 4C molecule to form 6C compound
  • 6C compound loses CO2 and Hydrogen to convert to a 4C compound and 1x ATP (via substrate-level phosphorylation)
  • The cycle can now continue.
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10
Q

Describe how oxidation takes place in glycolysis/ krebs?

A
  1. removal of H+
  2. by enzymes
  3. H accepted by NAD
  4. in krebs cycle FAD used
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11
Q

The Electron Transport Chain (ETC)

A

1.The reduced H carriers are oxidised losing Hydrogen.
2. The electrons pass down a series of electron carriers in a series of REDOX reactions.
3. As the electrons pass along the electron transport chain they lose energy, some of which is used to pump the H+ through the inner mitochondrial membrane into intermembrane space
4. Some of the energy is also lost as heat.
5. The H+ pass diffuse, down a proton gradient, into the matrix via ATP synthase enzymes and enough energy is provided to form ATP.
6. The electrons and H+ recombine with Oxygen gas to form water.
7. Oxygen is the final/terminal electron acceptor.
8. Without oxygen removing H+ and electrons, there would be a ‘back up’ of electrons along the ETC and the process of cellular respiration will come to a halt

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12
Q

Water is a waste product of aerobic respiration. Describe how water is formed at the end of aerobic respiration.

A
  • oxygen is terminal/final electron acceptor;
  • combines with electrons and protons (to form water);
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13
Q

Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP.

A

*reduced NAD
* electrons transferred from coenzyme to coenzyme
* energy released as electrons passed on
* energy used to synthesise ATP from ADP and Pi
* H+ / protons pumped into inter membrane space;
* H+ / protons diffuse back through ATP synthase enzyme;

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14
Q

Describe how ATP is made in mitochondria.

A
  • Substrate level phosphorylation
  • link reaction produces reduced NAD
  • Electrons released from reduced NAD
  • (Electrons) pass along carriers
  • Energy released
  • Protons pumped into inter membrane space;
  • ADP/ADP + Pi
  • ATP synthase;
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15
Q

Describe the events of oxidative phosphorylation

A
  • NAD/FAD reduced
  • ETC on cristae
  • electrons transferred from coenzyme to coenzyme
  • energy released as electrons passed on
  • protons pumped into intermembrane space
  • protons flow back through enzyme
  • energy used to synthesise ATP from ADP and phosphate
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16
Q

Anaerobic respiration

A

The Link reaction, Krebs cycle and electron transport chain stop as there is no Oxygen to act as the Final / terminal electron acceptor.

Glycolysis does not require Oxygen and can continue in the absence of Oxygen, however, for glycolysis to continue NAD must be regenerated.

The H from the reduced NAD in glycolysis is now accepted by pyruvate rather than passing through the electron transport chain.

The pyruvate is reduced to lactate in animals and ethanol & CO2 in plants.

17
Q

Respirometer expected results

A
18
Q

Explain how the amount of ATP is increased by reactions occurring inside a mitochondrion

A
  • oxidation of H+
  • from pyruvate
  • ATP produced in Krebs cycle;
  • production of reduced NAD / FAD
  • in matrix of mitochondria
  • electrons fed into electron transport chain
  • phosphorylation on cristae
  • linked to ATP production
  • ATP synthase
19
Q

Give two reasons why the respirometer was left for 10 minutes when it was first placed in the water bath.

A
  1. Equilibrium reached;
  2. Allow for expansion/pressure change in apparatus;
20
Q

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration.

A
  • Regenerates NAD /
    Oxidises reduced NAD;
  • (So) glycolysis continues;
21
Q

Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring cell.

A
  • Less reduced NAD
  • Oxygen is the final electron acceptor;
22
Q

In many mammals, ‘uncoupling proteins’ help to maintain a constant body temperature during hibernation.

Suggest and explain how.

A
  1. Allow passage of protons/H+;
  2. (Energy) released as heat
23
Q

Explain why a log scale is used to record the number of cells/bacteria.

A

Large range/difference/increase in numbers (of cells/bacteria);
Accept reference to exponential (increase)

Biology (29 decks)

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