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A Level (A2) OCR Biology > Unit 5.7- Respiration > Flashcards

Unit 5.7- Respiration Flashcards

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1
Q

Biological processes that require ATP:

A
  • Active transport
  • Endocytosis
  • Exocytosis
  • Synthesis of large molecules such as proteins
  • DNA replication
  • Cell division
  • Movement e.g. motor proteins walking along cytoskeleton threads
  • Activation of chemicals
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2
Q

How much energy is released from each phosphate ion hydrolysed from ATP?

A

Outer two: 30.5kJ

Inner one: 13.8kJ

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3
Q

Glycolysis definition:

A
  • First stage of respiration

- Converts glucose to pyruvate

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4
Q

What are the stages of glycolysis:

A
  • Phosphorilation of glucose to hexose bisphosphate
  • Splitting of each hexose bisphospahte molecule into two triose phosphate molecules
  • Oxidation of triose phosphate to pyruvate
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5
Q

What does NAD in glycolysis?

A
  • It is a coenzyme that helps dehydrogenease enzymes to carry out oxidation reactions
  • Oxidises molecules during glycolysis, the link reaction and the Krebs cycle
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6
Q

Structure of NAD:

A

Contains:

  • Adenine
  • Nicotinamide (vitamin B3)
  • Ribose
  • Two phosphoral groups
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7
Q

What can the nicotinamide ring of NAD accept?

A

Two hydrogen atoms to become reduced NAD

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8
Q

What does reduced NAD do?

A

Carries proteins and electron to the cristae of mitochondria and delivers them to be used in oxidative phosphorilation for the generation of ATP

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9
Q

What happens in the first stage of glycolysis (phosphorilation)?

A
  • One molecule of ATP is hydrolysed and the released phosphoryl group is added to glucose to make hexose monophosphate
  • Another molecule of ATP is hydrolysed and the phosphoryl group is added to the hexose monophosphate molecule to make hexose bisphosphate
  • The sugar has one phosphate group at carbon 1 and one at carbon 6
  • The energy from the hydrolysed ATP molecules activates the hexoses sugar and prevents it from being transported out of the cell
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10
Q

What happens in the second stage of glycolysis (Splitting the hexose bisphosphate)?

A
  • Each molecule of hexose bisphosphate is spit into two threee-carbon molecules, triose phosphate
  • Each has a phosphate group attached
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11
Q

What happens in the third stage of glycolysis (oxidation of triose phosphate to pyruvate)?

A
  • Dehydrogenase enzymes (and NAD) remove hydrogen from triose phosphate
  • The two molecules of NAD accept the hydrogen atom and become reduced NAD
  • Two moleules of NAD are reduced for every molecule of glucose undergoing this process.
  • Four molecules of ATP are made for every two triose phosphate molecules undergoing oxidation
  • This makes 2 pyruvate molecules. Each has 3 carbons
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12
Q

Why is oxidation of triose phosphate to pyruvate an oxidation reaction if it is anearobic?

A

It involves the removal of hydrogen atoms

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13
Q

What are the products of glycolysis?

A
  • Two molecules of ATP, (four have been made but two are used to start the reaction so the net gain is two)
  • Two molecules of reduced NAD
  • Two molecules of pyruvate
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14
Q

What are the stages of respiration?

A

-Glycolysis
-The link reaction
-The Krebs cycle
-Oxidative phosphorilation
The last three stages only take place under aerobic conditions. In the absence of oxygen, pyruvate is converted, in the cytoplasm, to lactate or ethanol.

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15
Q

Cristae definition:

A

Inner, highly-folded mitochondrial membrane. The intrusions

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16
Q

Mitichondrial matrix definition:

A

Fluid-filled inner part of the mitichondria

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17
Q

What is the shape of mitochondria?

A

Rod shaped, thread-like, or spherical

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18
Q

What is the diameter of a mitochondrion?

A

0.5-1um

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19
Q

What is the length of a mitichondrion?

A

2-5um but occasionally up to 10um

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20
Q

What kind of membrane do mitochondria have?

A
  • Outer and inner phospholipid membrane
  • Makes an envelope
  • Inner membrane folded into cristae to give a large surface area
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21
Q

What are embedded in the inner membrane of mitochondria?

A
  • Proteins that transport elections

- Protein channels associated with ATP synthase enzyme that allows protons to diffuse through them

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22
Q

What is between the inner and outer membranes of the mitochondria?

A

Intermembrane space

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23
Q

What is in the mitichondrial matrix?

A
  • Enzymes that catalyse stages of the link reaction and the Krebs cycle
  • Molecules of NAD and FAD
  • Oxaloacatate (4 carbon compound that accepts the acetyl group in the link reaction)
  • Mitochondrial DNA
  • Mitochondrial ribosomes
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24
Q

What is he structure of the outer mitichondrial membrane?

A

Phospholipid composition similar to that of other organelles in eukaryotic cells

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25
Q

What is the structure of the inner mitochondrial membrane?

A
  • Less permeable to small ions such as H+ than the outer membrane
  • The cristae give a large surface area for the electron carriers and ATP synthase enzymes all arranged in electron transport chains
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26
Q

What are electron transport chains involved in?

A

The final stage of aerobic respiration, oxidative phosporilation

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27
Q

Why can iron ions accept and donate electrons?

A

Because it can accept them, (becoming Fe2+), or donate them, (becoming Fe3+)

28
Q

What type of enzyme are electron carrier proteins?

A

Oxido-reductase enzymes

29
Q

How does the electron transport chain work?

A
  • The electron carriers have a coenzyme that uses energy released from electrons to pump protons from the matrix into the intermembrane space.
  • Protons accumulate in the intermembrane space and a gradient forms across the membrane
  • This causes a flow of flow of protons through the channels in the ATP synthase enzymes to make ATP
30
Q

What is a ATP enzyme?

A
  • Protons pass through from the intermembrane space to the matrix
  • This produces ATP
  • The ATP enzymes protrude from the inner membrane into the matrix
31
Q

Decarboxylation definition:

A

Removal of a carboxyl group from a substrate molecule

32
Q

Dehydrogenation definition:

A

Removal of hydrogen atoms from a substrate molecule

33
Q

Substrate-level phosphorylation definition:

A

Production of ATP from ADP and Pi during glycolysis and the Krebs cycle

34
Q

What happens to pyruvate after glycolysis?

A

It is transported across the outer and inner mitochondrial membranes vie specific pyruvate-H+ symports. There are transport proteins that transport two ions or molecules i the same direction

35
Q

Brieft overview of link reactions and Krebs cycle:

A
  • Pyruvate is converted into a two-carbon acetyl group

- The acetyl group is oxidised

36
Q

What happens in the link reaction?

A
  • Pyruvate (3C) is decarboxylated and dehydrogenated (catalysed by pyruvate dehydrogenase)
  • This forms an acetyl group which combines with coenzyme A to form acetyl CoA(2C), (reduced NAD and CO2 are produced)
37
Q

What is the equation for the link reaction?

A

2pyruvate + 2NAD + 2CoA -> 2CO2 + 2NADH + 2 acetylCoA

38
Q

What happens in the Krebs cycle

A
  • Acetyl group (2C) released from acetylCoA (2C) combines with oxaloacetate (4C) to form citrate (6C)
  • This is decarboxylated and dehydrogenated to produce a 5 carbon compound, one CO2 and one NADH
  • 5 carbon compound is further decarboxylated and dehydrogenated, producing a 4 carbon compound, one CO2 and one NADH
  • The 4 carbon compound bind temporarily with and is then released from coenzyme A. Substrate level phosphorylation takes place, which produces one ATP
  • 4 carbon compound is dehydrogenated, producing a different 4 carbon compound and one FADH
  • Rearrangement of atoms produces one oxaloacetate (4C) so the cycle can continue
39
Q

Krebs cycle molecules:

A
  • Acetyl group (2C) + oxaloacetate (4C) ->citrate (6C)
  • Citrate (6C) -> 5C (CO2, NADH)
  • 5C -> 4C (CO2, NADH)
  • 4C -> 4C (ATP)
  • 4C -> 4C (FADH)
  • 4C -> oxaloacetate (4C) (NADH)
40
Q

How many molecules of everything are produced in the link reaction from one molecule of glucose?

A
  • 2 NAHD
  • 0 FADH
  • 2 CO2
  • 0 ATP
41
Q

How many of everything are produced in the Krebs cycle from one molecule of glucose?

A
  • 6 NADH
  • 2 FADH
  • 4 CO2
  • 2 ATP
42
Q

What other substrates besides glucose can be respired aerobically?

A
  • Fatty acids are broken down into molecules of acetate that enter the Krebs cycle via acetyl CoA
  • Glycerol may be converted to pyruvate and enter the Krebs cycle via the link reaction
  • Amino acids may be deaminated and the rest of the molecule can enter the Krebs cycle directly or be changed to pyruvate or acetyl CoA
43
Q

Chemiosmosis definition:

A

Flow of protons, down their concentration gradient, across a membrane, through a channel associated with ATP synthase

44
Q

Oxidative phosphorilation definition:

A

The formation of ATP using energy released in the electron transport chain and in the presence of oxygen. It is the last stage of aerobic respiration

45
Q

What is the final electron acceptor?

A

Oxygen

46
Q

What is the equation for when oxygen is used as the final electron acceptor?

A

4H+ + 4e- + O2 -> 2H2O

47
Q

How many ATP molecules are produced at each stage of respiration from one glucose molecule?

A 
Glycolysis: 2
The link reaction: 0
The Krebs cycle: 2
Oxidative phosphorilation: 28
Total: 32
48
Q

Why in reality is there probably not going to be a whole 32 molecules of ATP produced from one glucose molecule?

A
  • Some ATP used to actively transport pyruvate into the mitochondria
  • Some ATP used in shuttle system that transports reduced NAD made in glycolysis, into mitchondira
  • Some protons may leak out through the mitochondrial membrane
49
Q

Why can’t aerobic respiration happen in the absence of oxygen?

A
  • Oxygen cannot act as final electron acceptor at the end of oxidative phosphorylation, so protons that have travelled through ATP synthase cannot combine with electrons and form water
  • Concentration of protons in matrix increases and reduces proton gradient across inner mitochiondrial membrane
  • Oxidative phosphorylation ceases
  • NADH and DADH can not unload their hydrogen atoms and can’t be reoxidised
  • The Krebs cycle stops and so does the link reaction
50
Q

Ethanol fermentation pathway equation:

A

Pyruvate -> (with pyruvate decarboxylase, releases CO2) -> ethanAl -> (with ethanOl dehydrogenase, NADH becomes NAD) -> ethanOl

CH3COCOOH -> (with pyruvate decarboxylase, releases CO2) -> CH3CHO -> (with ethanOl dehydrogenase, NADH becomes NAD) -> CH3CH2OH

51
Q

Lactate fermentation pathway equation:

A

Pyruvate -> (with lactate dehydrogenase, NADH becomes NAD) -> lactate

CH3COCOOH -> (with lactate dehydrogenase, NADH becomes NAD) -> CH3CHOHCOOH

52
Q

What happens to lactate after it is produced?

A
  • May be converted to pyruvate, which may enter the Krebs cycle via the link reaction
  • May be recycles to glucose and glycogen
53
Q

What would happen if lactate was not removed from the muscle tissues?

A

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

54
Q

Respiratory substrate definition:

A

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

55
Q

Which cells can only use glucose for respiration?

A

Some mammalian cells such as brain cells and erythrocytes

56
Q

What is changed about lipids so that part of it can be repsired?

A

Triglycerides are hydrolyses by lipase to glycerol and fatty acids. Glycerol can then be converted to triose phosphate and respired

57
Q

Why are fatty acids good for respiring?

A

They have lots of protons

58
Q

How do fatty acid chains enter the Krebs cycle?

A
  • Energy is used to combine each fatty acid with coenzyme A
  • The fatty acid- CoA complex is transported to the mitochondrial matrix, where it is broken into two-carbon acetyl groups, each attached to a CoA
  • This beta-oxidation pathway generates NADH and FADH
  • The acetyl groups are released from CoA and enter the Krebs cycle by combining with the four-carbon oxaloacetate
59
Q

Which part of proteins can be respired?

A

The keto acid

60
Q

How does a keto acid enter the respiratory pathway?

A

As pyruvate, acetyl CoA, or a Krebs cycle acid such as oxaloacetic acid

61
Q

Energy value for carbohydrates:

A

15.8kJg-1

62
Q

Energy value for lipids:

A

39.4kJg-1

63
Q

Energy value for proteins:

A

17.0kJg-1

64
Q

Respiratory quotient

A

RQ= CO2 produced / O2 consumed

65
Q

Respirometer definition:

A

Apparatus used to measure the rate of respiration of living organisms by measuring the rate of exchange of oxygen and carbon dioxide

66
Q

Setting up a respirometer:

A
  • Place coloured liquid into manometer tube and connect the apparatus with the taps open, enabling the air in the apparatus to connect with the atmosphere
  • Find mass of organism
  • With the taps still open, the whole set up, including organisms is placed in a water bath for at least 10 minutes, until it reaches the temperature of the water bath
  • Syringe plunger should be near the top of the scale on the syringe barrel, and its level noted
  • Levels of coloured liquid should be marked
  • Taps are closed and apparatus left in water bath for 10 minutes
  • Change in level of manometer liquid can be measured, and the syringe barrel depressed to reset apparatus. This also enables you to measure the volume of oxygen absorbed
  • Calculate the volume of oxygen absorbed per minute per gram of living organism
67
Q

What does the sodium hydroxide solution in a respirometer do?

A

Absorbs CO2

A Level (A2) OCR Biology (13 decks)

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