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Biology Module 5 > 5.7 Respiration > Flashcards

5.7 Respiration Flashcards

1
Q

what is the equation for aerobic respiration

A

glucose +water = carbon dioxide +water+energy

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2
Q

define respiration

A

the release of chemical potential energy from organic molecules

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3
Q

define the two metabolic processes

A

-catabolic (break down)
-anabolic (build up)

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4
Q

what is ATP

A

adenosine triphosphate
-it is a phosphorylated nucleotide
-cannot leave the cell where it is made

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5
Q

define hydrolysis

A

breaking molecules with the addition of water

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6
Q

define condensation

A

joining molecules resulting in removal of water

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7
Q

what can ATP be hydrolysed to

A

ADP + Pi

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8
Q

why is some energy released as heat

A

to keep living organisms warm and provide an optimum temperature for enzyme catalysed reactions

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9
Q

Why is ATP better than direct energy transfer

A

so cells can obtain the energy they need for a process in small manageable amount that will not cause damage or be wasteful

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10
Q

how much energy is released when ATP is catalysed by ATPases

A

ATP = ADP 30.5kJmol-1
ADP = AMP 30.5kJmol-1
AMP = adenosine 13.8kJmol-1

Total= 74.8kJmol-1

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11
Q

what is the role of ATP in the cell

A

-releases energy
-phosphate is removed in hydrolysis
-ADP can attach phosphate during respiration
-energy is released in small quantities to reduce waste

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12
Q

what are the 4 main processes in aerobic respiration

A
  1. glycolysis
  2. link reaction
  3. krebs cycle
  4. oxidative phosphorylation
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13
Q

define oxidation

A

loss of electrons/ hydrogen

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14
Q

define reduction

A

gain of electrons/ hydrogen

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15
Q

what does NAD do in respiration

A

NAD is a coenzyme. It accepts hydrogen molecules to form NADH (reduced NAD). This hydrogen can be removed and used to generate ATP

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16
Q

what is glycolysis

A

the first stage of respiration that converts glucose to pyruvate

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17
Q

where does glycolysis occur

A

in the cytoplasm

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18
Q

what are the 3 main stages of glycolysis

A
  1. phosphorylation of glucose to hexose bisphosphate
    2.lysis- splitting each hexose bisphosphate molecule into 2 triode phosphate molecules
  2. oxidation of triode phosphate to pyruvate
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19
Q

what are the 2 parts of glycolysis

A

energy investment phase - phosphorylation
energy pay off phase- oxidation

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20
Q

what is pyruvate

A

a 3 carbon sugar

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21
Q

Describe the NAD molecule

A

nicotinamide adenine dinucleotide
has 2 phosphate groups with an oxygen molecule between them.
each phosphate group is attached to ribose.
the bottom ribose is attached to adenine and the top one is attached to nicotinamide

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22
Q

describe the structure of ATP

A

3 phosphate groups which are joined with phosphoanhydride bonds
ribose which is joined to the phosphate by a phosphodiester bond
adenine which joins the ribose by a glycosidic bond

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23
Q

how does the structure of ATP compare to a nucleotide

A

-both have pentose sugar (ribose)
-ATP has 3 phosphate, nucleotide has 1
-both can have adenine

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24
Q

describe glycolysis

A

Glucose has 6 carbons
2 ATP are hydrolysed forming 2 ADP and they donate the phosphate groups to the glucose forming hexose bisphosphate (phosphorylation)
This goes through lysis forming 2x triose phosphate . 2 phosphate groups from the cytoplasm attach to each triose phosphate forming triose bisphosphate. 2 ADP take away the phosphate groups from the triose bisphosphates forming ATP. NAD takes away a hydrogen molecule becoming NADH (reduced NAH) (oxidation) forming pyruvate. 1 glucose molecule produces 2 pyruvate (3 carbon molecule)

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25
Q

what are the products of glycolysis

A

-2 ATP
-2 NADH
-2 pyruvate

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26
Q

what happens to the pyruvate that is produced during glycolysis

A

it is transported across the outer and inner mitochondrial membranes via specific pyruvate H+ symport into the fluid filled matrix of the mitochondria

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27
Q

define decarboxylation

A

removing carboxyl group

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28
Q

define dehydrogenation

A

removing hydrogen

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29
Q

describe the link reaction

A

pyruvate (3C molecule) goes through decarboxylation and dehydrogenation with the use of pyruvate dehydrogenase and pyruvate decarboxylase which changes it to an acetyl group (2 carbon molecule). The acetyl group combines with Coenzyme A becoming Acetyl Coenzyme A

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30
Q

describe the Krebs cycle

A

Acetyl Coenzyme A (2C molecule) reacts with oxaloacetate (4C molecule). Coenzyme A is removed and returns to the link reaction to be reused. 6C molecule is formed called Citrate. Co2 is released and NAD takes 2 hydrogen which forms a 5C compound and NADH. Decarboxylation and dehydrogenation occurs again which forms a 4C compound (oxaloacetate) and NADH. ATP, 2 molecules of reduced NAD, one molecule of FAD and carbon dioxide form in this step.

31
Q

What are the products of the link reaction per glucose molecule

A

2 NADH
2 Co2

32
Q

what are the products of the Krebs cycle per glucose molecule

A

6 NADH
2 reduced FAD
4 Co2
2 ATP

33
Q

define chemiosmosis

A

flow of protons down their conc. gradient across a membrane, through a channel associated with ATP synthase

34
Q

define oxidative phosphorylation

A

the formation of ATP using energy released in the electron transport chain and in the presence of oxygen

35
Q

where does oxidative phosphorylation take place and what does it involve

A

In mitochondria and it involves electron carrier proteins, arranged in chains called the electron transport chains, embedded in the inner mitochondrial membranes

36
Q

What happens to NADH and FADH at the electron transport chain

A

NADH and FADH are deoxidised when they deliver their hydrogen atoms to the electron transport chain.
The hydrogen atoms released from the reduced coenzymes split into protons and electrons and the protons go into solution in the mitochondrial matrix

37
Q

describe what happens at the electron transport chain

A

the electrons from the hydrogen atoms pass along the chain of electron carriers. Each electron carrier has an iron ion and they can gain an electron becoming reduced iron. The reduced iron ion can donate the electron to the iron ion in the next electron carrier in the chain, becoming reoxidised. As electrons pass down the chain, some of their energy is used to pump protons across the inner mitochondrial membrane into the intermembrane space.

38
Q

describe the proton gradient

A

as protons accumulate in the intermembrane space, a proton gradient forms across the membrane. this gradient generates a chemiosmotic potential (proton motive force) and it is a source of potential energy. ATP is made using the energy of the proton motive force.

39
Q

describe chemiosmosis

A

protons cannot diffuse through the lipid bilayer of the mitochondrial membranes . however, they can diffuse through protein channels associated with ATP synthase enzymes that are in the inner membrane. As protons diffuse down their concentration gradient, the flow of protons causes a shape change in the ATP synthase enzyme that allows ADP to combine with Pi, forming ATP. The formation of ATP this way is called oxidative phosphorylation and the final electron acceptor is oxygen.

39
Q

describe chemiosmosis

A

protons cannot diffuse through the lipid bilayer of the mitochondrial membranes . however, they can diffuse through protein channels associated with ATP synthase enzymes that are in the inner membrane. As protons diffuse down their concentration gradient, the flow of protons causes a shape change in the ATP synthase enzyme that allows ADP to combine with Pi, forming ATP. The formation of ATP this way is called oxidative phosphorylation and the final electron acceptor is oxygen.

40
Q

after oxidation phosphorylation, what happens to the electrons?

A

They are accepted by oxygen. It combines with electrons coming off the electron transport chain and with protons, diffusing down the ATP synthase channel, forming water.

41
Q

what is the total amount of ATP made during aerobic respiration per glucose molecule

A

glycolysis- 2
link- 0
krebs- 2
oxidative phosphorylation- 28
total- 32

42
Q

why is the theoretical yield of ATP rarely achieved

A

-some ATP is used to actively transport pyruvate into the mitochondria
-some ATP is used in a shuttle system that transported NADH made during glycolysis into mitochondria
-some protons may leak out through the mitochondrial membrane

43
Q

describe the structure of the mitochondrion

A

-can be rod shaped, thread like or spherical
-outer membrane is smooth, inner membrane is folded into cristae
-inner membrane contains proteins that transport electrons and protein channels associated with ATP synthase that allow protons to diffuse

44
Q

what does the mitochondrial matrix contain

A

contains mitochondrial ribosomes, looped DNA and enzymes for the link reaction and Krebs cycle
molecules of coenzymes NAD and FAD
oxaloacetate

45
Q

what is the function of oxaloacetate

A

accepts acetyl group from link reaction

46
Q

what is the function of mitochondrial DNA

A

codes for mitochondrial enzymes and proteins

47
Q

describe the outer membrane of the mitochondrion

A

contains proteins, some which form channels or carriers that allow passage of molecules such as pyruvate into the mitochondrion

48
Q

describe the inner membrane of the mitochondrion

A

-lipid bilayer is less permeable to small ions than outer membrane
-cristae gives large surface area for electron carriers and ATP synthase embedded in it
-electron carriers are protein complexes arranged in electron transport chains

49
Q

describe the inter membrane space of the mitochondrion

A

-between inner and outer layers of the mitochondrial envelope
-inner membrane is in close contact with the mitochondrial matrix so molecules of NADH and FADH can easily deliver hydrogens to the electron transport chain

50
Q

what is substrate level phosphorylation

A

when ATP is given off at glycolysis and krebs cycle

51
Q

what happens to respiration when oxygen is absent

A

oxidative phosphorylation does not occur and link and krebs stop so only glycolysis occurs which produces 2 ATP. But in order for glycolysis to keep running, the NADH must be reoxidised to lose the hydrogen. Fungi and Mammals have two processes to reoxidise the NADH

52
Q

what are the two metabolic pathways that eukaryotic cells use to reoxidise NADH

A

Fungi and plants use the ethanol fermentation pathway
Mammals use the lactate fermentation pathway

53
Q

describe the ethanol fermentation pathway

A

pyruvate gets catalysed by pyruvate decarboxylase (CO2 is given off) to form ethanal and ethanal gets catalysed by ethanol dehydrogenase (NADH is reoxidised) to form ethanol.

54
Q

describe the lactate fermentation pathway

A

pyruvate gets catalysed by lactate dehydrogenase (NADH is reoxidised) and forms lactate

55
Q

what are the 2 outcomes of the lactate fermentation pathway

A

-pyruvate is reduced to lactate
-NADH is deoxidised into NAD

56
Q

where is lactate produced

A

It is produced in muscle tissue and is carried away from muscles in the blood to the liver

57
Q

what happens to lactate when more oxygen is available

A

-lactate converts to pyruvate which may enter the Krebs cycle via link
-lactate can be recycled to glucose and glycogen

58
Q

what would happen if lactate was not removed from the muscle tissue

A

the PH would lower and this would inhibit the action of many of the enzymes involved in glycolysis and muscle contraction

59
Q

How much ATP is released in anaerobic respiration

A

ethanol and lactate fermentation pathways do not release ATP but they allow glycolysis to continue. Only 1/15 of ATP produced in aerobic respiration is released because glucose is only partly broken down

60
Q

define respiratory substrate

A

organic substance which can be oxidised by respiration, releasing energy to make molecules of ATP

61
Q

How does glucose act as a chief respiratory substrate

A

it can be stored as glycogen in mammals or starch in plants as it can be hydrolysed to glucose for respiration

62
Q

how can disaccharides be used for respiration

A

they can be converted into monosaccharides and can be changed by isomerase enzymes into glucose

(monosaccharides such as fructose and galactose)

63
Q

how can lipids (fats) be respired

A

triglycerides can be hydrolysed by lipase to glycerol and fatty acids. Glycerol can then be converted to triose phosphate, enter glycolysis and be respired. The fatty acids are activated by reacting with CoEnzyme A in the cytoplasm. This enters the mitochondrial matrix where it is broken down into 2 carbon acetyl groups each attached to COA. The beta oxidation pathway generates NADH and FADH. The acetyl groups are released from CoA and enter the Krebs cycle by combining with oxaloacetate

64
Q

Why do we respire glucose first rather than fats

A

because to respire fats, it takes a lot of energy to break the bonds even though it produces a lot more ATP

65
Q

which respiratory substrate produces the most energy

A

lipids (39.4kj)
proteins (17kj)
carbohydrates (15.8kj)

66
Q

how can proteins be respired

A

excess amino acids are deaminated in the liver (which removes the amino group). The rest of the amino acid (a keto acid) enters the respiratory pathway as pyruvate, acetyl CoA or as a Krebs cycle acid such as oxaloacetic acid. During fasting/starvation, when glucose or lipids are insufficient, protein from muscles can be hydrolysed to amino acids which are then respired.

67
Q

how do you work out the respiratory quotient

A

Co2 produced/ O2 consumed

68
Q

Using the respiratory quotient, how can you identify if the molecule is a carbohydrate

A

value is close to 1

69
Q

Using the respiratory quotient, how can you identify if the molecule is an amino acid

A

value is around 0.9

70
Q

Using the respiratory quotient, how can you identify if the molecule is a fatty acid

A

value is around 0.7

71
Q

Using the respiratory quotient, how can you identify if anaerobic respiration is taking place

A

the value is above 1

72
Q

why will the fluid in a respirometer move towards the living organism doing respiration

A

as the Co2 will be swapping with O2 as the Co2 would be getting absorbed in the filter paper

Biology Module 5 (7 decks)

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