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Photosynthesis And Respiration > Respiration > Flashcards

Respiration Flashcards

1
Q

What are the two forms of cellular respiration?

A
  • Aerobic respiration
  • anaerobic respiration
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2
Q

What are the conditions of aerobic respiration? What does it produce?

A
  • requires oxygen
  • produces carbon dioxide, water and lots of ATP
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3
Q

What are the conditions of anaerobic respiration? What does it produce?

A
  • takes place in the absence of oxygen
  • produces lactate in animals, and ethanol & carbon dioxide in plants & fungi, doesn’t produce much ATP
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4
Q

What are the four stages of aerobic respiration?

A
  • glycolysis
  • link reaction
  • Krebs cycle
  • oxidative phosphorylation
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5
Q

What is glycolysis?

A

The splitting of the 6-carbon molecule into two 3-carbon pyruvate molecules

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6
Q

What happens in the link reaction?

A

The 3-carbon pyruvate molecules enter into a series of reactions which leads to the formation of acetylcoenzyme A, a 2-carbon molecule

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7
Q

What happens in the krebs cycle?

A

Acetylcoenzyme A is introduced into a cycle of oxidation-reduction reactions that yield some ATP and a large quantity of reduced NAD and FAD

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8
Q

What happens in oxidative phosphorylation?

A

The use of electrons, associated with reduced NAD and FAD, released from the Krebs cycle to synthesise ATP with water produced as byproduct

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9
Q

What is the initial stage of aerobic and anaerobic respiration?

A

Glycolysis

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10
Q

Where does glycolysis take place?

A

The cytoplasm

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11
Q

Where does the link reaction take place?

A

The matrix of the mitochondria

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12
Q

Describe the link reaction

A

Pyruvate molecules transported to matrix of mitochondria;

  • pyruvate oxidised to acetate, in this reaction the 3-carbon pyruvate molecule loses a carbon dioxide molecule and two hydrogens—hydrogens accepted by NAD to form reduced NAD, which is later used to produce ATP
  • 2-carbon acetate combines with a molecule called coenzyme A (CoA) to produce acetylcoenzyme A
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13
Q

What is the overall equation of the link reaction?

A

Pyruvate + NAD + CoA —> Acetylcoenzyme A + reduced NAD + CO2

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14
Q

Who worked out the sequence for the Krebs cycle?

A

Hans Krebs

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15
Q

Describe what happens in the Krebs cycle

A
  1. The 2-carbon acetylcoenzyme A from the link reaction combines with a 4-carbon molecule to create a 6-carbon molecule
  2. In a series of reactions this 6-carbon molecule loses carbon dioxide and oxygen to give a 4-carbon molecule and a single molecule of ATP produced as a result of substrate level phosphorylation
  3. The 4-carbon molecule can now combine with a new molecule of acetylcoenzyme A to begin the cycle again
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16
Q

What is produced for each pyruvate molecule in the link reaction and Krebs cycle?

A
  • reduced coenzymes (NAD, FAD- have potential to provide energy to produce ATP molecules by oxidative phosphorylation and are therefore important in Krebs cycle)
  • one molecule of ATP
  • three molecules of carbon dioxide
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17
Q

What is the yield from a single glucose molecule?

A

Double what is produced for pyruvate molecules

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18
Q

What are coenzymes?

A

Molecules that some enzymes require in order to function

19
Q

What are some examples of coenzymes? Where are they important?

A
  • NAD- important throughout respiration
  • FAD- important in Krebs cycle
  • NADP- important in photosynthesis
20
Q

How does NAD work?

A

Works with dehogrynase enzymes that catalyses hydrogen and transfers them to other molecules in oxidative phosphorylation

21
Q

What is the significance of the Krebs cycle?

A
  • breaks up macromolecules into smaller ones- pyruvate into carbon dioxide
  • produces hydrogen that’s carried by NAD to the electron transfer chain and provides energy for oxidation phosphorylation— leads to production of ATP that provides metabolic energy for the cell
  • regenerates 4-carbon molecule that combines with acetylcoenzyme A, which would otherwise accumulate
  • source of intermediate compounds used by cells in the manufacture of other substances such as fatty acids, amino acids and chlorophyll
22
Q

What carries hydrogen atoms into oxidative phosphorylation?

A

Coenzymes FAD and NAD

23
Q

Where is the site of oxidative phosphorylation?

A

The mitochondria

24
Q

What are some adaptations in the mitochondria to help carry out oxidative phosphorylation?

A
  • within the cristae are enzymes and other proteins involved in oxidative phosphorylation
25
Q

Where does mitochondria appear in great numbers? What are their features in these cells?

A
  • muscle, liver and epithelial cells
  • more densely packed cristae, wh
26
Q

What are the first three stages of the chemiosmotic theory

A

1- the hydrogen atoms produced during glycolysis and the Krebs cycle combine with the coenzymes NAD and FAD.

  1. The reduced NAD and FAD donate electrons of the hydrogen atoms they are carrying to the first molecule in the electron transfer chain
  2. Electrons pass along chain of electron transfer carrier molecules in a series of oxidation-reduction reactions. As electrons flow along chain, the energy they release causes the active transport of protons across the inner mitochondrial membrane and into the inner-membranal space
27
Q

What are stages 4 & 5 of the chemiosmotic theory?

A

4- protons accumulate in the inner-membranal space before they diffuse back into the mitochondrial matrix through ATP synthase channels embedded in the inner mitochondrial membrane.

5- at the end of the chain the electrons combine with these protons and oxygen to form water. Oxygen is the final acceptor of electrons in the electron transfer chain

28
Q

What is the final acceptor of electrons in the electron transfer chain?

A

Oxygen

29
Q

What is the importance of oxygen in respiration?

A

To act as the final acceptor of the hydrogen atoms produced in glycolysis and the Krebs cycle

30
Q

What would happen if oxygen wasn’t present in respiration for its role in removing hydrogen atoms at the end of the chain?

A

The hydrogen ions and electrons would ‘back up’ along the chain and the process of respiration would come to a halt.

31
Q

What is the difference between energy being released in one big step vs little at a time

A
  • big step= most energy is released as heat, less available for useful purposes
  • little by little= more of it can be harvested for the benefit of the organism
32
Q

Why are electrons passed down a transfer chain, each of which at a slightly lower energy level, by NAD and FAD?

A

So that more energy can be harvested for the benefit of the organism, as the gradient allows their energy to be released more gradually and therefore more usefully

33
Q

What are alternative respiratory substrates to sugars?

A
  • lipids
  • proteins
34
Q

What happens before lipids can be respired?

A

They are hydrolysed to glycerol and fatty acids

35
Q

What happens to the glycerol and fatty acids after lipids are hydrolysed in respiration

A
  • glycerol- phosphorylated and converted to triosphosphate, which enters glycolysis pathway and Krebs cycle
  • fatty acids- broken down into 2-carbon fragments, converted to acetylcoenzyme A, enters Krebs cycle
36
Q

What is produced in the oxidation of lipids? What happens to these products?

A
  • 2- carbon fragments of carbohydrate and many hydrogen atoms.
  • hydrogen atoms- used to produce ATP during oxidative phosphorylation
37
Q

What happens to proteins before respiration? What then happens?

A
  • hydrolysed to its constituent amino acids
  • they have their amino group removed before entering the respiratory pathway at different points depending on the number of carbon atoms they contain,
    3- carbon compounds become pyruvate, while 4 and 5-carbon molecules are converted into intermediates in the Krebs cycle
38
Q

What two types of anaerobic respiration occur with any regularity in eukaryotic cells?

A
  • in plants, microorganisms such as yeast, pyruvate is converted to ethanol and carbon dioxide
  • in animals, pyruvate is converted to lactate
39
Q

Give an example where anaerobic respiration leading to the production of ethanol take place?

A

Root cells under waterlogged conditions

40
Q

Give the equation of the production of ethanol from pyruvate and the hydrogen from reduced NAD

A

Pyruvate + reduced NAD —> ethanol + carbon dioxide + oxidised NAD

41
Q

What is an advantage of anaerobic respiration in animals?

A

Overcomes places with a temporary shortage of oxygen

  • baby mammals straight after birth
  • an aquatic animal where oxygen is sometimes low
42
Q

What is oxygen debt?

A

Where oxygen is used up more rapidly than it can be supplied

43
Q

What two ways does can energy be derived from cellular respiration?

A
  • substrate- level phosphorylation in glycolysis and the Krebs cycle. This is the direct transfer of phosphate from a respiratory intermediate to ADP to produce ATP
  • oxidative phosphorylation in the electron transfer chain. This is the indirect linking of energy from phosphate to ADP to produce ATP involving energy from hydrogen atoms that are carried on NAD and FAD. Cells produce more of their ATP this way
44
Q

In anaerobic respiration, what is pyruvate converted to?

A
  • ethanol
  • lactate

Photosynthesis And Respiration (3 decks)

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