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A2 Biology > Respiration, energy and ATP > Flashcards

Respiration, energy and ATP Flashcards

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1
Q

Why do organisms require energy?

A
  • Metabolic reactions/enzymes
  • Movement
  • Active Transport
  • Maintenance, repair and division
  • Production of substances
  • Maintain body temperature
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2
Q

What is ATP made of?

A

ADP and Pi (inorganic phosphate)

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3
Q

What is used to covert ATP back to ADP?

A

Water, hydrolysis reaction

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4
Q

What is phosphorylation?

A

The addition of a phosphate group to a molecule

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5
Q

What are the 3 types of phosphorylation?

A

Photo, oxidative and substrate-level phosphorylation

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6
Q

What is photophosphorylation?

A

The use of light energy from photosynthesis to ultimately provide the energy to convert ADP to ATP

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7
Q

What is oxidative phosphorylation?

A

The formation of ATP in the electron transport chain of aerobic respiration

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8
Q

What is substrate-level phosphorylation?

A

When phosphate groups are transferred from donor molecules to ADP to make ATP, occurs in both plant and animal cells

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9
Q

Why is ATP a better immediate energy source than glucose?

A
  • Each ATP molecule releases less energy than a glucose molecule, so energy released in more smaller and manageable quantities
  • The hydrolysis of ATP to ADP is a single reaction that releases energy immediately whereas the break down of glucose is a longer series of reactions and energy release takes longer
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10
Q

What is ATP the source of energy for?

A
  • Metabolic processes e.g. protein synthesis from amino acids
  • Movement i.e. muscle contraction
  • Active transport across plasma membranes
  • Secretion
  • Activation of molecules e.g. allowing enzyme-catalysed reactions to occur more readily
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11
Q

What are the two types of cellular respiration?

A

Aerobic and anaerobic (fermentation)

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12
Q

What is the difference between aerobic and anaerobic respiration?

A

Aerobic requires oxygen and produces C02, H20 and ATP whereas Anaerobic takes place in the absence of oxygen and produces lactate in animals or ethanol and CO2 in plants, however for both cases only a little bit of ATP is generated

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13
Q

What are the 4 stages of aerobic respiration?

A
  1. Glycolysis
  2. Link Reaction
  3. Krebs’s Cycle
  4. Electron transport chain (ETC)
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14
Q

Which stage of respiration can only occur during anaerobic respiration?

A

Glycolysis

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15
Q

Where does glycolysis occur?

A

Cytoplasm of cells

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16
Q

What does glycolysis involve?

A

A hexose (6-carbon) sugar, usually glucose, is split into two molecules of the 3-carbon molecule pyruvate

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17
Q

What happens to glucose during glycolysis?

A

Oxidised to pyruvate

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18
Q

What are the 4 stages of glycolysis?

A
  1. Activation of glucose by phosphorylation - Two ATP molecules are hydrolysed to ADP to provide the energy to activate glucose as it lowers the activation energy for the enzyme-controlled reactions that follow
  2. Splitting of the phosphorylated glucose - Each glucose is split into two 3-carbon molecules, triose phosphate
  3. Oxidation of triose phosphate - Removal of hydrogen from each triose phosphate molecule and transferred to NAD which is reduced to NADP
  4. Production of ATP - Each triose phosphate molecule is converted into pyruvate and in the process, two molecules of ATP are regenerated from ADP
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19
Q

What are the products of glycolysis?

A

2 molecules of ATP, 2 molecules of pyruvate and 2 molecules of NADH

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20
Q

What happens in the link reaction after glycolysis?

A

Pyruvate produce from glycolysis in cytoplasm are actively transported into the matrix of the mitochondria

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21
Q

Where does the link reaction occur?

A

Matrix of mitochondria

22
Q

What series of reactions occur in the link reaction?

A
  • Pyruvate oxidised by removing hydrogen, which is accepted by NAD to form NADH
  • The 2-carbon molecule, acetyl group, combined with coenzyme A to form acetyl coenzyme A
  • A C02 molecule is formed from each pyruvate
23
Q

What is the equation for the link reaction?

A

Pyruvate + NAD + CoA -> Acetyl CoA + NADH + CO2

24
Q

Where does the Kreb’s cycle take place?

A

Matrix of mitochondria

25
Q

What happens during the Kreb’s cycle?

A

A series of oxidative/reduction reactions

26
Q

What happens to the 2-carbon acetyl CoA from the link reaction in the Kreb’s cycle?

A

Combines with a 4-carbon molecule to produce a 6-carbon molecule

27
Q

What happens to the 6-carbon molecule formed in the Kreb’s cycle as a result of acetyl CoA combing with a 2-carbon molecule?

A

It loses CO2 and hydrogen to give a 4-carbon molecule and one molecule of ATP

28
Q

Why does the 6-carbon molecule formed in Kreb’s cycle become a 4-carbon molecule, as well as produce a single molecule of ATP?

A

Substrate-level phosphorylation

29
Q

What can happen to the 4-carbon molecule in the Kreb’s cycle after it has been produced from the 6-carbon molecule?

A

Combine with a new molecule of acetyl CoA and start the cycle again

30
Q

What is produced from every pyruvate molecule in the link reaction and Kreb’s cycle?

A
  • NADH and FADH
  • One molecule of ATP
  • Three molecules of C02
31
Q

What are coenzymes?

A

Molecules that some enzymes require in order to function

32
Q

Which coenzyme is used throughout respiration?

A

NAD

33
Q

What is the function of NAD in respiration?

A

Works alongside dehydrogenase enzymes that catalyse the removal of hydrogen ions from substrates and transfer them to other molecules

34
Q

What is the significance of the Kreb’s cycle?

A
  • Breaks down macromolecules (large ones) into smaller ones e.g. pyruvate into C02
  • Produces hydrogen ions that are carried by NAD to the ETC for oxidative phosphorylation
  • Regenerates the 4-carbon molecule that combines with acetyl CoA
  • Source of intermediate compounds used by cells in the manufacture of other important substances e.g. amino acids
35
Q

Where does the electron transport chain take place?

A

Inner folded membrane (cristae) of mitochondria

36
Q

What happens during the electron transport chain?

A

The energy of electrons within the hydrogen atoms is converted into a form that cells can use (ATP)

37
Q

Why do the mitochondria in the metabolically active cells, such as muscle cells, have more densely packed cristae?

A

To provide a greater surface area for the attachment of enzymes and other proteins involved in the ETC

38
Q

What are the main stages of the electron transport chain?

A
  1. NAD and FAD attached to the cristae of mitochondria receive hydrogen atoms from glycolysis and Kreb’s cycle
  2. Reduced NAD and FAD donate their electrons they are carrying to first molecule in ETC
  3. This molecule releases the protons from the hydrogen atom and are actively transported across the inner membrane
  4. Meanwhile electrons pass along a chain of electron transport molecules in a series of oxidation-reduction reactions
  5. Electrons lose energy as they pass down chain
  6. Protons accumulate in space between the two mitochondrial membranes before diffusing back into the matrix
  7. At the end of the chain the electrons combine with these protons and oxygen to form water
39
Q

What is the final electron acceptor in the electron transport chain?

A

Oxygen

40
Q

What happens to the energy lost by the electrons as they pass down the ETC?

A

Some is used to combine ADP and inorganic phosphate to make ATP and the remaining energy is released as heat

41
Q

Why is oxygen important in respiration?

A

Without its role in removing hydrogen atoms at the end of the chain (final acceptor) the hydrogen ions and protons and electrons would back up along the chain and the process of respiration would come to a halt

42
Q

What needs to happen for glycolysis to continue in anaerobic respiration?

A

The products of pyruvate and hydrogen must be constantly removed

43
Q

What needs to happen to the hydrogen from reduced NAD in order for glycolysis to continue?

A

Must be released from NADH to regenerate NAD, so that there is NAD to take up the hydrogen newly produced from glycolysis

44
Q

What happens to the pyruvate in anaerobic respiration in plants and microorganisms?

A

Converted to ethanol (alcohol) and C02

45
Q

What happens to the pyruvate in anaerobic respiration in animals?

A

Converted to lactate (lactic acid)

46
Q

What is the equation for anaerobic respiration in plants and microorganisms?

A

pyruvate + NADH -> ethanol + C02 + NAD

47
Q

What is the equation for anaerobic respiration in animals?

A

pyruvate + NADH -> lactate + NAD

48
Q

What does the pyruvate have to do during anaerobic respiration in plants and microorganisms?

A

Lose a molecule of C02 and accept the hydrogen from NADH to produce ethanol

49
Q

What does the pyruvate have to do during anaerobic respiration in animals?

A

Each molecule produced takes up the two hydrogen atoms from NADH produced in glycolysis to form lactate

50
Q

What is common to anaerobic respiration in both plants and animals?

A

NAD needed for glycolysis is regenerated

51
Q

How many molecules of ATP are produced in aerobic respiration?

A

38 ATP

52
Q

How many molecules of ATP are produced in anaerobic respiration?

A

2 ATP

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