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Alevel Biology > 5.7 > Flashcards

5.7 Flashcards

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1
Q

What is respiration

A

Respiration is a process that occurs in living cells and releases energy stored in organic molecules like glucose

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2
Q

What is energy released from organic molecules immediately used to synthesise

A

Molecules of ATP from ADP and inorganic phosphate (pi)

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3
Q

Why is ATP hydrolysed in cells

A

To release energy needed to drive biological processes

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4
Q

What organisms respire to obtain energy

A

Microorganisms(eukaryotes like yeast and prokaryotes like bacteria), plants, animals, fungi and protoctist

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5
Q

What is energy

A

The capacity to work

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6
Q

What is potential energy

A

Energy stored in complex organic molecules like fats, carbs and proteins

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7
Q

What is chemical energy

A

Converted from light energy in photosynthesis

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8
Q

What happens when energy is released from organic molecules via respiration

A

It can be used to make ATP to drive biological processes

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9
Q

examples of biological processes that ATP are needed for

A

Active transport, endocytosis, exocytosis, synthesis of large molecules, DNA replication
Cell division, movement of flagella/cilia, moving organelles, activation of chemicals

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10
Q

What is glucose at the start of respiration and what does this mean

A

It is phosphorylated so becomes more reactive and can be broken down to release more energy

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11
Q

What are all chemical reactions within a cell known as

A

Metabolism or metabolic reactions

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12
Q

What are anabolic reactions

A

Are metabolic reactions where large molecules are synthesised from small molecules

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13
Q

What is catabolic reaction

A

Metabolic reaction involving hydrolysis of large to smaller molecules

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14
Q

Within living cells what allows atoms, ions and molecules to move

A

Kinetic energy

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15
Q

What energy is used in diffusion

A

When molecules move down their concentration gradient the molecules have kinetic energy

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16
Q

What is ATP

A

Standard intermediary between energy releasing and energy consuming metabolic reactions in both eukaryotic and prokaryotic cells

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17
Q

What is ATP structure

A

It is a phosphorylated nucleotide and each ATP has adenosine, nitrogenous base-adenine, 5 carbon sugar ribose and 3 phosphate groups

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18
Q

Is ATP stable or unstable

A

Relatively stable in solution in cells but readily hydrolysed by enzyme catalysis. But while in solution it can be easily moved place to place within a cell

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19
Q

What is energy releasing hydrolysis of ATP coupled with

A

An energy consuming metabolic reaction, ATP is an immediate energy source for this metabolic reaction

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20
Q

What happens when ATP is hydrolysed to ADP + Pi

A

A small quantity of energy is released for use in cells, so cells can obtain energy they need for a process in small manageable amounts that won’t cause damage or be wasteful

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21
Q

Why is ATP referred to as universal energy currency

A

It occurs in all living cells and is a source of energy that can be used by cells in small amounts

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22
Q

What is some energy released as from hydrolysis of ATP

A

Heat energy, the release of heat in both respirator and during hydrolysis may appear inefficient and wasteful but heat helps keep living organisms warm and enables their enzyme catalysed reaction to proceed at or near optimum rate

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23
Q

What is the chemical energy released from hydrolysis of ATP

A

ATP+H2O -> 30.5kJmol-1 + Pi -> ADP+H2O -> 30.5kJmol-1 + Pi -> AMP+H2O -> 13.8 kJmol*-1 + Pi -> adenosine

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24
Q

What is glycolysis

A

Is biochemical pathway that occurs in cytoplasm of all living organisms that respire including many prokaryotes

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25
Q

What does glycolysis involve

A

Pathway involves sequence of 10 reactions, each catalysed by different enzymes, some with help of coenzyme, NAD

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26
Q

What are the 3 main stages of glycolysis

A
  1. phosphorylation of glucose to hexose biphosphate
  2. splitting each hexose biphospahte molecules into 2 triose phosphate molecules
  3. oxidation of triose phosphate to pyruvate
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27
Q

What are the 4 stages to glycolysis

A

Activation- glucose+2ATP -> phosphorylated hexose+2ADP
Splitting- phosphorylated hexose-> 2x3C sugars triose phosphate
Oxidation-2x3C sugars triose phosphate+2NAD-> 2x oxidised 3C sugars
Conversion-2x oxidised 3C sugars+4Pi+4ADP->3 pyruvate (3C) + 4ATP

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28
Q

What do enzymes that catalyse oxidation and reduction reactions need

A

Need help of coenzymes that accept hydrogen atoms removed during oxidation

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29
Q

What is NAD

A

A non-protein molecule that helps dehydrogenase enzymes to carry out oxidation reactions, NAD oxidises substrate molecules during glycolysis, link reaction and kerbs cycle

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30
Q

Where is NAD synthesised and what by

A

Synthesised in living cells from nicotinamide, 5 carbon ribose, nucleotide base adenine and 2 phosphoryl groups, nicotinamide ring can accept 2 hydorgen atoms becoming reduced NAD

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31
Q

What is reduced NAD

A

NAD when nicotinamide accepts 2 hydrogen atoms

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32
Q

What does reduced NAD do

A

Carries protons and electrons to cristae of mitochondria and delivers them to be used in oxidative phosphorylation from generation of ATP to ADP+Pi

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33
Q

What happens to reduced NAD when it gives up protons and electrons that is accepted during 1 of 1st stages of respiration

A

It becomes oxidised and can be reduced to oxidise more substrate in the process becoming reduced again

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34
Q

What sugar is glucose

A

Hexose sugar meaning it contains 6 carbon atoms, it’s molecules are stable and need to be activated before they can be split into 2-3 carbon compounds

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35
Q

What happens in phosphorylation in glycolysis

A
  1. 1 molecule of ATP is hydrolysed and released phosphoryl group added to glucose to make hexose monophosphate 2.another molecule of ATP is hydrolysed and phosphoryl group added to hexose phosphate to form a molecule of hexose biphosphate, this sugar has 1 phosphate group at carbon 1 and another at carbon 6. Energy from hydrolysis of ATP molecules activates hexose sugar and prevents it being transported outside the cell
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36
Q

What happens in splitting of hexose bisphosphate in glycolysis

A

Each molecule of hexose bisphosphate is split into 2-3 carbon molecules, triose phosphate, each with a phosphate group attached

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37
Q

What happens in oxidation of triose phosphate to pyruvate in glycolysis

A

Although process is anaerobic it involves oxidation as it involves removal of hydrogen atoms from substrate molecules. 1.dehydrogenase enzymes, aided by coenzyme NAD, remove hydrogen from triose phosphate 2. 2 molecules of NAD accept hydrogen atoms and become reduced 3. At this stage of glycolysis 2 NAD molecules were reduced for every molecule of glucose undergoing this process and 4 molecules of ATP made for every triose phosphate molecule undergoing oxidation

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38
Q

Stages of glycolysis

A

Phosphorylation-> splitting -> oxidation-> conversion

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39
Q

What are the products of glycolysis

A

For each glucose molecule at the end of glycolysis there are:
2 molecules of ATP, 4 made but 2 were used at the start, so net gain is 2ATP
2 molecules of reduced NAD
2 molecules of pyruvate

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40
Q

What are the 4 stages of respiration of glucose

A

1.glycolysis 2.link reaction 3.kerbs cycle 4.oxidative phosphorylation

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41
Q

What happens to respiration in anaerobic conditions

A

After glycolysis either lactate or ethanol fermentation occurs to produce either lactate or ethanol and CO2

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42
Q

What happens after glycolysis is aerobic conditions

A

Link reaction where pyruvate turns to acetyl coenzymeA then kerbs cycle which released CO2 and oxidative phosphorylation

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43
Q

What do the last 3 stages of respiration require

A

Only take place in aerobic conditions

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44
Q

In aerobic conditions what happens directly after glycolysis

A

Pyruvate molecules are actively transported into mitochondria for link reaction

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45
Q

Where does glycolysis occur

A

Cytoplasm

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46
Q

In anaerobic conditions what happens to pyruvate after glycolysis

A

It is converted in the cytoplasm to ethanol or lactate and in this process reduced NAD molecules are reoxidised so glycolysis can continue to run, generating 2 molecules of ATP for every glucose molecule metabolised

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47
Q

Where are mitochondria found

A

They are organelles in all types of eukaryotes

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48
Q

What shape are mitochondria

A

Rod or spherical shape

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49
Q

What is mitochondria structure

A

Have inner and outer phospholipid membrane making an envelope, the outer membrane is smooth and inner membrane folded into cristae giving larger surface area

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50
Q

What is embedded in mitochondria inner membrane

A

Proteins that transport electrons and protein channels associated with ATP synthase enzyme that allow protons to diffuse through them

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51
Q

What is between inner and outer mitochondrial membrane

A

Inter-membrane space

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52
Q

What is the structure of mitochondrial matrix enclosed by inner membrane

A

It is semi ridged and gel like, it contains ribosomes, looped DNA and enzymes for links reaction and Krebs cycle

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53
Q

How does the matrix enable mitochondria to carry out its function

A

Matrix where links reaction and kreb cycle takes place contains enzymes that catalyse stages of these reactions, molecules of coenzymes NAD and FAD, oxaloacetate (4C compound that accepts acetyl from link reaction), mitochondrial DNA (codes for mitochondrial enzymes and other proteins), mitochondrial ribosomes

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54
Q

How does the outer membrane enable mitochondria to carry out its function

A

Phospholipid composition of outer membrane similar to other organelle membranes in eukaryotes, it contains proteins, some of which form channels or carriers that allow cells adage of molecules, like pyruvate into mitochondrion

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55
Q

How does the inner membrane enable mitochondria to carry out its function

A

Lipid composition of inner membrane differs form outer membrane, the lipid bilayer is less permeable to small ions like H+ (protons) than outer membrane, folds in inner membrane give large SA for electron carriers and ATP synthase enzymes embedded in them, electron carriers are protein complexes arranged in electron transport chains, they are involved in final stage of aerobic respiration (oxidative phosphorylation)

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56
Q

How does the inter membrane space enable mitochondria to carry out its function

A

Inter membrane space between outer and inner layer of mitochondrial envelope involved in oxidative phosphorylation, inner membrane is in close contact with mitochondrial matrix so molecules of reduced NAD and FAD can easily deliver hydrogen to electron transport train

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57
Q

What does each electron carrier protein contain

A

A cofactor (a non protein haem group that contain an iron ion)

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58
Q

What can iron ions do

A

Can accept and donate electrons as it can become reduced (Fe2+) by gaining electron and then oxidised (Fe3+) when donating electron to nest electron carrier

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59
Q

What are electron carrier proteins

A

Oxido-reductase enzymes

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60
Q

What do electron carriers have and what’s its function

A

Have Coenzymes that using energy released from electrons, pumps protons from matrix to intermembrane space so a proton gradient forms across membrane

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61
Q

What does a proton gradient across membrane produce

A

A flow of protons through channels in ATP synthase enzymes to make ATP

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62
Q

What are ATP synthase enzymes

A

They are large and protrude from inner membrane into matrix

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63
Q

What can pass through ATP synthase enzymes

A

Protons

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64
Q

What is another name for stalked particles

A

ATP synthase

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65
Q

How is pyruvate made in glycolysis transporter across and and inner mitochondrial membrane

A

Via specific pyruvate H+ symport (a transport protein that transports 2 ions or molecules in the same direction) and into the matrix

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66
Q

What happens once pyruvate is transported into the matrix by pyruvate H+ symports

A
  1. pyruvate converted into 2 carbon acetyl group during link reaction
  2. acetyl group is oxidised during kerbs cycle
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67
Q

What does link reaction occur

A

Mitochondrial matrix

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68
Q

What happens in the link reaction

A

Pyruvate is decarboxylated (loss of o2) and dehydrogenated (loss of H+), catalysed by a large multi enzyme complex, pyruvate dehydrogenase, which catalyses sequence of reactions that occur during link reaction

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69
Q

How much ATP produced in link reaction

A

No ATP produced

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70
Q

What is step one of link reaction

A

Carboxyl group removed form pyruvate and is the origin of some of the CO2 produced during respiration

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71
Q

What is step two of link reaction

A

2.the decarboxylation of pyruvate together with dehydrogenation produces acetyl group

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72
Q

What is step 3 of link reaction

A

Acetyl group combines with coenzyme A (CoA) to become acetyl coenzyme A

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73
Q

What is step 4 of link reaction

A

Coenzyme NAD becomes reduced

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74
Q

What is the equation to summarise link reaction for 2 molecules of pyruvate derived from 1 glucose molecule

A

2 pyruvate + 2NAD + 2CoA -> 2co2 + 2 reduced NAD + 2 acetyl coenzyme A

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75
Q

How does coenzyme A accept the acetyl group

A

In the form of acetyl coenzyme A and carriers the acetyl group to kerbs cycle

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76
Q

What does Krebs cycle occur

A

Matrix

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77
Q

What is the Krebs cycle

A

Series of enzyme catalysed reactions that oxidise acetate from link reaction to 2 molecules of CO2 while converting energy to be reducing coenzyme NAD and FAD

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78
Q

What do the reduced NAD and FAD coenzymes do in Krebs cycle

A

They carry hydrogen atoms to electron chain on cristae where they’ll be involved in production of many more ATP molecules

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79
Q

What is step 1 of Krebs cycle

A

Acetyl group is released from acetyl coenzyme A and combines with 4 carbon compound, oxaloacetate, to form 6 carbon compound, citrate

80
Q

What is step 2 of Krebs cycle

A

Citrate is decarboxylated and dehydrogenated, producing a 5 carbon compound, 1 molecule of CO2 and 1 molecule of reduced NAD

81
Q

What is step 3 of Krebs cycle

A

5 carbon compound is further dehydrogenated and decarboxylated producing 4 carbon compound, 1 molecule of CO2 and 1 molecule of reduced NAD

82
Q

What is step 4 of Krebs cycle

A

4 carbon compound combines temporarily with and then released from coenzyme A, at this stage substrate level phosphorylation takes place, producing 1 molecule of ATP

83
Q

What is step 5 of Krebs cycle

A

4 carbon compound is dehydrogenated, producing different 4 carbon compound and a molecule of reduced FAD

84
Q

What is step 6 of Krebs cycle

A

Rearrangement of atoms in 4 carbon molecule, catalysed by isomerase enzyme, followed by further dehydrogenation, regenerate a molecule of oxaloacetate so cycle can continue

85
Q

How many turns of the Krebs cycle are there for each glucose molecule

A

2 turns

86
Q

How much reduced NAD produced by link reaction

A

2

87
Q

How much reduced FAD produced by link reaction

A

0

88
Q

How much carbon dioxide produced by link reaction

A

2

89
Q

How much ATP produced by link reaction

A

0

90
Q

How much reduced NAD produced by Krebs cycle

A

6

91
Q

How much reduced FAD produced by Krebs cycle

A

2

92
Q

How much carbon dioxide produced by Krebs cycle

A

4

93
Q

How much ATP produced by Krebs cycle

A

2

94
Q

Is oxygen used in link reaction and Krebs cycle

A

Not directly but they occur in presence of oxygen so they are aerobic

95
Q

What has occurred by end of Krebs cycle

A

Production of CO2 from glucose is completed

96
Q

What other substrates besides glucose can be respires aerobically

A

Fatty acids are broken down to many molecules of acetate that enter Krebs cycle via acetyl coenzyme a, glycerol maybe converted to pyruvate and enter Krebs cycle via link reaction, amino acids may be deaminated (amine group removed) and rest of molecule can enter Krebs cycle directly or be change to pyruvate or acetyl coenzyme a

97
Q

What is the final stage of aerobic respiration

A

Oxidative phosphorylation

98
Q

What is oxidative phosphorylation and where does it occur

A

Production of ATP in presence of oxygen and takes place in mitochondria

99
Q

What is chemiosmosis

A

Involves electron carrier proteins, arranged in chains called electron transport chains embedded in inner mitochondrial membrane (cristae)

100
Q

What is purpose of flooded cristae

A

Give large surface area for electron carrier proteins and ATP synthase enzymes

101
Q

What is step one of oxidative phosphorylation

A

Reduced NAD and reduced FAD are reoxidised when they deliver their hydrogen atoms to the electron transport chain

102
Q

What is step two of oxidative phosphorylation

A

Hydrogen atoms released from reduced coenzymes split into protons and electrons

103
Q

What is step 3 of oxidative phosphorylation

A

Proton goes into solution in mitochondrial matrix

104
Q

What passes along chain of electron carriers

A

Electrons from each atom pass along chain of electron carriers

105
Q

What does each electron carrier protein have at its core

A

An iron ion which can gain an electron to become reduced (Fe2+)

106
Q

What can a reduced iron ion do in electron transport chain

A

It can then donate electron to iron ion in the next electron carrier becoming reoxidised (Ge3+)

107
Q

What happens as electrons pass along electron transport chain

A

Some of their energy is used to pump protons across inner mitochondrial membrane into inter membrane space

108
Q

What happens as protons accumulate in inter membrane space

A

A proton gradient forms across membrane which generates a cheiosmotic potential known as a proton motive force

109
Q

What is a proton motive force

A

They are a source of potential energy (ATP made using energy of proton moving force)

110
Q

Why can protons easily diffuse through lipid bilayer of mitochondrial membrane

A

As outer membrane has low degree of permeability to protons and inner membrane is impermeable to protons

111
Q

How do protons diffuse through mitochondrial membranes

A

Through protein channels associated with ATP synthase enzymes that are in the inner membrane

112
Q

What happens as protons diffuse down their concentration gradient through protein channels

A

The flow of protons causes a conformational change in ATP synthase enzymes that allow ADP and Pi to combine to form ATP

113
Q

What is the flow of protons known as

A

Chemiosmosis

114
Q

What is the formation of ATP in the presence of oxygen by causing a conformational change to ATP synthase enzymes known as

A

Oxidative phosphorylation

115
Q

How is oxygen a final electron acceptor in oxidative phosphorylation

A

It combines with electrons coming off electron transport chains and with protons diffusing down ATP synthase channels, forming water

116
Q

What does this equation summarise: 4H+ + 4e- + O2 -> 2H2O

A

The combination of oxygen with electrons coming off electron transport chains and with protons diffusing down ATP synthase channels, forming water

117
Q

How many reduced NAD and reduced FAD were produced in glycolysis

A

Reduced NAD - 2 and reduced FAD - 0

118
Q

How many reduced NAD and reduced FAD were produced in link reaction

A

Reduced NAD - 2 and reduced FAD - 0

119
Q

How many reduced NAD and reduced FAD were produced in Krebs cycle

A

Reduced NAD - 6 and reduced FAD - 2

120
Q

What do reduced coenzymes provide to electron transport chain

A

Both protons and electrons

121
Q

How much ATP can be produced from protons and electrons from 10 molecules of reduced NAD (2 in glycolysis, 2 in link, 6 in Krebs)

A

In theory it can produce 25 ATP molecules

122
Q

How many ATP molecules can be produced from protons and electrons from 2 molecules of reduced FAD

A

In theory 3 ATP molecules

123
Q

How many ATP molecules can be produced during oxidative phosphorylation

A

28 ATP molecules per molecule of glucose

124
Q

What was the net gain of ATP per glucose molecule in glycolysis

A

2

125
Q

What was the net gain of ATP per glucose molecule in link reaction

A

0

126
Q

What was the net gain of ATP per glucose molecule in Krebs cycle

A

2

127
Q

What was the net gain of ATP per glucose molecule in Oxidative phosphorylation

A

28

128
Q

What was the net gain of ATP per glucose molecule in total

A

32

129
Q

Is the theoretical yield of ATP every achieved

A

Rarely it’s more often net gain of 30

130
Q

Why do we not usually reach the theoretical net gain of ATP

A

Some ATP used to actively transport pyruvate into mitochondria, some ATP used in shuttle system that transports reduced NAD, made during glycolysis, into mitochondria, some protons may leak out through outer mitochondrial membrane

131
Q

What happens if oxygen is absent in respiration

A

1.oxygen can’t act as final electron acceptor at end of oxidative phosphorylation, protons diffusing through channels associated with ATP synthase can’t combine with electrons and o2 to form water 2.concentration of protons increases in matrix and reduces proton gradient across inner mitochondrial membrane 3.oxidative phosphorylation ceases 4.reduced NAD and reduced FAD can’t unload their hydrogen atoms and can’t be reoxidised 5.Krebs cycle and link reaction stop

132
Q

How do organisms survive in absence of oxygen

A

Glycolysis can take place but reduced NAD generated during oxidisation of triose phosphate to pyruvate has to be reoxidised so glycolysis can continue, these reduced coenzymes molecules can’t be reoxidised at electron transport chain, so another metabolic pathway must operate to reoxidise them

133
Q

What are the 2 metabolic pathways eukaryotes have to reoxidse reduced NAD

A

Fungi and plants use ethanol fermentation pathway and mammals use lactate fermentation pathway

134
Q

Where do lactate and ethanol fermentation pathways take place

A

In cells cytoplasm

135
Q

What is stage one of ethanol fermentation pathway

A

Each molecule of pyruvate produced during glycolysis is decarboxylated and converted to ethanal, this stage is catalysed by pyruvate decarboxylase which has a coenzyme, thiamine diphosphate, bound to it

136
Q

What is stage two of ethanol fermentation pathway

A

Ethanal accepts hydrogen atoms from reduced NAD, becoming reduced to ethanol and enzyme ethanol dehydrogenase catalyses the reaction

137
Q

What is stage three of ethanol fermentation pathway

A

In the process reduced NAD is reoxidised and made available to accept more hydrogen atoms from triose phosphate, allowing glycolysis to continue

138
Q

Where does lactate fermentation occur

A

In mammalian muscle tissue during vigorous activity like running to escape predator, when demand of ATP for muscle contraction is high and there’s an oxygen deficit

139
Q

What is step one of lactate fermentation pathway

A

Pyruvate produced during glycolysis accepts hydrogen atoms from reduced NAD, also made during glycolysis, the enzyme lactate dehydrogenase catalyses the reaction and there are 2 outcomes 1.pyruvate reduced to lactate 2.reduced NAD becomes reoxidised

140
Q

What is step two of lactate fermentation pathway

A

Reoxidised NAD can accept more hydrogen atoms from triose phosphate during glycolysis and glycolysis can continue to produce enough ATP to sustain muscle contraction for a short period

141
Q

Where is lactate produced and where is carried to

A

Produced in muscle tissue and carried away from muscle tissue in blood to the liver

142
Q

What may happen to lactate when more oxygen is available

A

It may be converted to pyruvate which may enter Krebs cycle via links reaction or be recycled to glucose and glycogen

143
Q

What would happen if lactate weren’t removed from muscle tissues

A

pH would be lowered and this would inhibit action of many enzymes involved in glycolysis and muscle contraction

144
Q

How much ATP does lactate and alcohol fermentation produce

A

Nether produce any ATP

145
Q

Even though lactate and ethanol fermentation don’t produce ATP how is ATP produced

A

They allow glycolysis to continue so net gain of 2 ATP molecules per glucose molecule is still obtained

146
Q

How is the overall net yield of ATP quite large in anaerobic respiration

A

Glucose is only partially broken down so many more molecules can undergo glycolysis per min

147
Q

For each molecule of glucose what is the proportion of the yield of ATP with anaerobic respiration compared to aerobic respiration

A

1/15

148
Q

What is yeast

A

A facultative anaerobe, it’s a single celled fungus and eukaryotic, it contains mitochondria and they reproduce asexually by mitosis

149
Q

How do yeast respire when oxygen is present

A

Aerobically by glycolysis, link reaction, Krebs cycle and oxidative phosphorylation producing many ATP molecules per glucose molecule

150
Q

What do yeast cells require to divide

A

ATP

151
Q

What does rate of production of ATP depend on in yeast cells

A

Rate of production of yeast cells depends on amount of ATP available l, we would expect yeast to have faster rate of reproduction under aerobic conditions

152
Q

What can yeast also do under aerobic conditions

A

Can oxidise ethanol

153
Q

What can yeast cells do with oxygen

A

Can oxidise ethanol and any sugar in cider and is not killed by alcohol, they will respire aerobically and produce ATP for cell division

154
Q

WhT do yeast cells do in anaerobic conditions

A

Ethanol can’t be oxidised and will eventually kill yeast, so when respiration is aerobic, more yeast cells should be present per cm3 at end of the week

155
Q

How would you investigate respiration rates in yeast

A

1.add cider and yeast suspension and cover with muslin cloth to stop dust entering but allowing oxygen in 2.leave flask in warm place for a week 3.use drop off solution in haemocytometer and count number of yeast cells. More yeast cells = aerobic respiration

156
Q

How do u use a haemocytometer

A

1.breathe on underside of coverslip to moisten it 2.horizontally slide coverslip onto slide and carefully press down 3.when coverslip in good position you will see 6 rainbow patterns, depth of central chamber 0.1mm 4.place pipette tip at entrance to groove and leg lipid fill chamber, leave 5mins before counting 5.place haemocytometer slide on microscope stage and focus using x40 magnification 6.then x100 and central section of grid will now fill field of view 7.count cells in central and 4 corner squares

157
Q

What other ways can be used to compare aerobic and anaerobic respiration in yeast

A

Rate of respiration can be measured by measuring rate of evolution of CO2, as CO2 dissolved in culture medium it lowers the pH and this is measured using pH meter

158
Q

Which molecules can also provide respiratory substrates

A

Carbs, lipids and proteins

159
Q

How are carbs lipids and proteins respiratory substrates

A

They can be oxidised in presence of oxygen to produce ATP molecules, CO2 and water

160
Q

Do carbs lipids and proteins all have the same relative energy values

A

No they are all different

161
Q

What is the biggest carb respiratory substrate

A

Monosaccharide Glucose

162
Q

Why is glucose an important respiratory substate

A

Some mammalian cells like brain and red blood cells can only use glucose for respiration

163
Q

How do animals and some bacteria store carbs

A

As glycogen which can be hydrolysed to glucose for respiration

164
Q

How do plant cells store carbs

A

As starch which can also be hydrolysed to glucose for respiration

165
Q

How are disaccharides prepped for respiration

A

They can be digested to monosaccharides

166
Q

How are monosaccharides like fructose and galactose changed to make glucose for respiration

A

Can be changed by isomerase enzymes

167
Q

What tissues are lipids important respiratory substrates for

A

Many tissues like muscle tissue

168
Q

How are triglycerides used in respiration

A

They are hydrolysed by lipase to glycerol and fatty acids and glycerol can then be converted to triose phosphate and respired

169
Q

What are fatty acids

A

Long chain hydrocarbons with a carboxylic acid group, songs in each molecule there are many carbon and hydrogen atoms and few oxygen atoms

170
Q

What are fatty acids a source of

A

Many protons for oxidative phosphorylation and so fats produce much more ATP than equivalent mass of carbs

171
Q

How is fatty acid used in respiration

A

1.with help of energy from hydrolysis of 1ATP molecule to AMP, each fatty acid combines with coenzyme A 2.fatty acid coenzyme A complex is transported to mitochondrial matrix where it’s broken down to 2carbon acetyl groups, each attached to CoA 3.this beta oxidation pathway generates reduced NAD and reduced FAD 4.acetyl groups are released from CoA and enters Krebs cycle by combing w 4C oxaloacetate

172
Q

For every acetyl group oxidised in Krebs cycle how may reduced NAD, reduced FAD and ATP made by substrate level phosphorylation

A

3 reduced NAD, 1 reduced FAD, 1 ATP

173
Q

What happens to excess amino acids

A

They are released after digestion of proteins and deaminated in the liver

174
Q

What does deaminated of amino acid involve

A

Removal of amino group and its subsequent conversion to urea that’s removed via kidneys, rest of amino acid molecule l, keto acid, enters respiratory pathway as pyruvate, acetyl CoA or Krebs cycle acid like oxaloacetic acid

175
Q

What happens during fasting, starvation or prolonged exercise when insufficient glucose or lipids are available for respiration

A

Protein from muscle can be hydrolysed to amino acids which are then respired, these amino acids may be converted to pyruvate or acetate and enter Krebs cycle

176
Q

What stage is most of ATP produced in aerobic respiration made

A

Oxidative phosphorylation

177
Q

What does greater availability of protons for chemiosmosis equal

A

More ATP can be produced, more hydrogen atoms therefore the more ATP that can be generated per molecule of substrate

178
Q

What happens as protons (hydrogen ions) combine with oxygen atoms to form water

A

The greater the proportion of hydrogen atoms in a molecule the more oxygen needed for its respiration

179
Q

What is carb, lipid and protein mean energy value in kJ g-1

A

Carbs-15.8, lipid-39.4, protein-17.0

180
Q

How is respiratory quotient for different respiratory substrates calculated

A

RQ=CO2 produced/o2 consumed

181
Q

If RQ value is greater than 1 what does it indicate

A

Some anaerobic respiration taking place as it shows more CO2 is being produced than oxygen being consumed

182
Q

What would RQ value of glucose be - C6H12O6 + 6O2 -> 6CO2 +6H2O

A

RQ= 6/6=1

183
Q

What do organisms absorb and give out when they aerobically respire

A

Absorb o2 and give out CO2

184
Q

When using a respirometer what does it mean if CO2 produced is absorbed by soda lime

A

Then the only volume change within respirometer is due to oxygen volume absorbed by the organism

185
Q

When using a respirometer what does it mean if oxygen is absorbed from the tube with the organism

A

Then that tube has reduced volume of air in it, exerting less pressure than the greater volume of air in the other tube, as a result coloured liquid in manometer tube rises upwards to respirometer tube(look at image of respirometer)

186
Q

When can volume of CO2 absorbed during a specific period be calculated with a respirometer

A

If original level of liquid in manometer tube is marked and radius of bore in the capillary tube is known

187
Q

How do you reset respirometer apparatus

A

Syringe is depressed to inject air into system and reset the liquid in manometer tube back to original position which allows a reading of volume of oxygen absorbed by noting change in level of syringe plunger as measured from graduated scale on syringe barrel

188
Q

How do u set up the apparatus for a respirometer to test respiration rates (steps 1-4)

A

1.after placing coloured liquid, methylene blue solution w 1 drop of detergent, into the manometer tube, apparatus is connected with taps open enabling air in apparatus to connect with atmosphere 2.mass of living organism found 3.w taps open whole setup and living organism in place, it’s placed in water bath for 10min until it reaches water baths temp 4.syringe plunger should be near top of scale on syringe barrel and it’s level noted

189
Q

How do u set up the apparatus for a respirometer to test respiration rates (steps 5-8)

A

5.levels of colour in manometer tubes marked with felt tip pen or Chinagraph pencil 6.taps closed and apparatus left in water bath for specific period like 10mins 7.change in level of manometer liquid can be measured and syringe barrel depressed to reset apparatus, enabling u to measure volume of oxygen absorbed 8.u can then calculate volume of oxygen absorbed per min per gram of living organism

190
Q

How is effect of temp on respiration rate investigated

A

Using a respirometer, 3 readings should be taken at each temp

191
Q

What should happen in between temp readings when investigating effect of temp of respiration rate

A

Apparatus and organism should be allowed time to adjust to new temp

192
Q

What organisms r suitable to measure rate of respiration

A

Blowfly maggots, woodlice, yeast in glucose suspension liquid or soaked pea seeds beingning to germinate

193
Q

When can animals be used when measuring effect of temp on respiration rate

A

Only with narrow temp range, 10-40degreesC (extreme temps fungal material used)

194
Q

Effect of temp on respiration rate

A

Higher temp faster respiration rate as more enzyme catalysed reactions occur till a certain temp when the enzymes denature

195
Q

How would you investigate effect of substrate concentration on respiration rate in yeast

A

Respirometer used so suspension of yeast, with differing concentrations of glucose solutions, is placed in one of the tubes, if sodium hydroxide solution is omitted, evolution of CO2 during a specific time period can be measured

Alevel Biology (25 decks)

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