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A level Biology - Regular > Chapter 18 - Respiration > Flashcards

Chapter 18 - Respiration Flashcards

1
Q

What are the steps of respiration ?

A

1) Glycolysis
- Anareobic
1. Fermentation
- Aerobic
1. Link reaction
2. Krebs cycle
3. Electron Transport Chain

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2
Q

What occurs during Glycolysis ?
What are the steps ?

A

1) Phosphorylation - 2Pi are released from 2ATP to make Hexosebisphosphate
2) Lysis - Destabilises Hexosebisphoate and splits into 2 Triosephosphate
3) Phosphorylation - Another Pi is added to each triose bisphosphates (Pi comes from cytoplasm)
4) Dehydrogenation - 2 Triose bisphosphate molecules are oxidised by removal of hydrogen to form 2 pyruvate NAD Coenzyme accepts the released Hydrogens

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3
Q

What is Glycolysis an example of and why ?

A

Substrate level phosphorylation
- Formation of ATP without the use of ETC
- ATP is formed via the transfer of Pi from triose bisphosphate

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4
Q

What is produced from Glycolysis ?

A

NET :
- 2 ATP
- 1 NADH
- 2 Pyruvates

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5
Q

What is the link reaction also known as ?

A

Oxidative decarboxylation

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6
Q

What occurs during the Link reaction ?

A

1) Pyruvate enters mitochondrial matrix from cytoplasm via active transport
2) Pyruvate will then undergo OXIDATIVE DECARBOXYLATION as it is decarboxylated and oxidated. NAD will be reduced to pick up the hydrogen; turning into NADH
3) The resulting acetyl group is bonded to coenzyme A forming acetylcoenzyme A

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7
Q

What happens directly after the link reaction ?

A

The remaining Acetly coA delivers the acetyl group to the Krebs cycle
The NADH produced will be used in oxidative phosphorylation to synthesise ATP

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8
Q

What are the features of the krebs cycle ?

A

Location : Mitochondrial Matrix
One cycle results in the breakdown of acetyl group
Involves decarboxylation, dehydrogenation, and susbtrate level phosphorylation

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9
Q

What occurs in the Krebs cycle ?

A

1) 2C Acetyl group joins with 4C oxaloacetate to form 6C citrate
2) Citrate undergoes decarboxylation and dehydrogenation; producing NAD and CO2 and 5C compound
3) 5C compound undergoes further decarboxylation and dehydrogenation; regenerating oxaloacetate. Therefore the cycle continues

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10
Q

What is produced during the Krebs cycle ?

A

CO2
2 NADH is produced
1 FADH2 os produced
ATP is produced via substrate level phosphorylation

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11
Q

What are the 2 coenzymes used and made in respiration ?
Why are they important ?

A

NAD
FAD
Required to transder protons and electrons

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12
Q

What are the differences between NAD and FAD ?

A

NAD
- Takes part in all stages of respiration
- Accepts one hydrogen
- Oxidised at the start of the ETC
- NADH results in the synthesis of 3 ATP

FAD
- Only takes part in Krebs and ETC
- Accepts 2 Hydrogen
- FAD is oxidised further along the chain
- FADH results in the synthesis of 2 ATP

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13
Q

Where do we get coenzymes from ?

A

Derived from vitamins

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14
Q

What occurs after the Krebs cycle ?

A
  • Hydrogen atoms frmom NADH and FADH are delivered to the ETC present in the membreanes of cristae of the mitochondria
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15
Q

What occurs in the Electron Transport Chain ?

A
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16
Q

What does oxygen act as ?

A

Final electron acceptor
2e- + 0.5O2 + 2H+ -> H2O

17
Q

Where does the NAD and FAD go after ETC ?

A

NAD returns to glycoclysis
FAD returns to krebs

18
Q

What happens during Chemiosmosis ?

A

ADP joins with Pi to form ATP via the movement of H+ ions past ATP synthase

19
Q

Why is the ETC and chemiosmosis known as oxidative phosphorylation ?

A

Oxidative - Oxygen is the final electron acceptor
Phosphorylation - Pi are used to phosphorylate ADP to ATP

20
Q

What is the difference between substrate level phosphorylation and oxidative phosphorylation ?

A

Substrate level phosphorylation - the production of ATP involves the transfer of phosphate groups from a highly reactive intermediate
Oxidative phosphorylation - the flow of electrons down an electrochemical gradient through ATP synthase thereby producing ATP

21
Q

How many ATP does aerobic respiration produce ?

A

38 molecules of ATP per glucose is produced in aerobic respiration as oppose to 2 in anaerobic respiration

22
Q

What is an obligate anaerobe ?

A
  • Cannot survive in the presence of oxygen
  • Prokaryotes
23
Q

What is a facultative anaerobe ?

A
  • Synthesise ATP if oxygen is present
  • Can switch to anaerobic respiration when O2 is not available e.g. yeast
24
Q

What is an obligate aerobe ?

A
  • Can only synthesise ATP where O2 is present
  • Are NOT facultative as although anaerobic respiration can occur, toxic waste ir produced that must be broken
25
Q

Why can aerobic respiration not continue when there is a lack of oxygen ?

A

Oxygen cannot act as a final electron acceptor; meaning ETC stops and NADH and FADH are no longer able to be oxidise ATP hence krebs cycle stops which causes glycolysis to stop too due to the lack of NAD

26
Q

What is fermintation ?

A
  • Form of anaerobic respiration-process by which complex compounds are broken down without the use of Oxygen
  • Not all glucose is broken down hence only a small quantitiy of ATP is produced - only produced by substrate level phosphorylation as chemiosmosis is not possible
27
Q

What are the two types of fermentation ?
Which organism does which type ?

A

1) Lactate fermintation (Animals)
2) Alcoholic fermintation (Plants)

28
Q

What occurs during Lactate fermintation ?

A

1 - Pyruvate acts as a hydrogen acceptor from NADH (Catalysed by Lactate dehydrogenase)
2 - This converts pyruvate into lactic acid and NAD is regenerated which is used to keep glycolysis ongoing

29
Q

Why does Lactate fermintation put the body in Oxygen debt ?

A

Lactate is made and needs to be converted back into glucose in the liver but for this to happen Oxygen is required

30
Q

Why can Lactate fermintation not occur forever ?

A
  • The low conc. of ATP produced is not enough to sustain vital processes for a long period of time
  • Accumulation of Lactic acid causes a fall in Ph leading to proteins denaturing
31
Q

What occurs during Alcoholic fermintation ?

A

1 - Pyruvate is converted into Ethanal (Catalysed by pyruvate decarboxylate) by the removal of CO2
2 - Ethanal then accepts H+ from NADH; regenerating NAD to be used in glycolysis
3 - This converts Ethanal into Ethanol
This is an irreversible process

32
Q

What is a respiratory substrate ?

A

Any organic molecule that is broken down to release energy for the synthesis of ATP

33
Q

What are the 3 main respiratory substrates ?
What are their Rq values ?

A

Carbohydrates = 1.0
Proteins = 0.9
Lipids = 0.7

34
Q

What is the equation for Respiratory quotient ?

A

Rq = CO2 produced/O2 consumed

35
Q

What produces more energy lipids or proteins ?
Why ?

A

Lipids
Although its respiratory quotient is less, gram for gram Lipids produce more energy due to it being a bigger molecule
Lipids contain lots of C-H bonds hence it requires more O2 to break down and releases less CO2

A level Biology - Regular (14 decks)

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