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A-level biology component 1 (+immunology) > Aerobic Respiration > Flashcards

Aerobic Respiration Flashcards

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1
Q

What type of process is respiration?

A

-a catabolic process involving a series of enzyme-catalysed reactions in cells. -Energy-rich substrates (e.g. glucose and fatty acids) are hydrolysed to release energy; some is trapped as chemical energy in ATP and some is released as heat energy.

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2
Q

What happens during respiration?

A

-high energy C-C, C-H and C-OH bonds are broken by enzymes in a series of small steps.
-These reactions provide the energy to produce ATP.

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3
Q

What is aerobic respiration?

A

-the release of large quantities of ATP energy from glucose or another organic substrate in the presence of oxygen. -Carbon dioxide is produced.

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4
Q

what is anaerobic respiration?

A

takes place in the absence of oxygen and produces lactate in animal cells and carbon dioxide and ethanol in yeast cells, together with a small yield of ATP energy.

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5
Q

What are two substrates that can be used to release energy in respiration?

A

glucose and fatty acids

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6
Q

Most of the energy released during respiration is used to synthesise ATP.
How is the rest of the energy released?

A

heat

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7
Q

What are the similarities between aerobic respiration and anaerobic respiration?

A

-both produce carbon dioxide (anaerobic only yeast/plant cells)
-both use ATP
-both use glucose as a substrate

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8
Q

What are the differences between aerobic respiration and anaerobic respiration?

A

-anaerobic does not require oxygen whereas aerobic does require oxygen;
-aerobic makes 38 ATP per glucose wheat as anaerobic makes 2 ATP
-both reactions start in the cytoplasm bit aerobic includes the mitochondria

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9
Q

What is anaerobic respiration in animals and yeast/plants?

A

-yeast/plants- glucose—>ethanol +CO2
-animal cells- glucose—> lactic acid (no gas (CO2) produced)

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10
Q

what is ATP and what does it stand for?

A

-nucleotide found in all living organisms
-stands for Adenosine triphosphate

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11
Q

What does ATP synthase do?

A

catalyses the condensation reaction which makes ATP

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12
Q

Where is energy stored?

A

in lipids or carbohydrates like glucose

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13
Q

What does respiration do to glucose?

A

oxidises glucose in a series of small reactions to release energy in the form of ATP- ATP is not an energy store but an energy source.

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14
Q

How is ATP involved in energy changes?

A

by carrying the energy to where it is needed and releasing the energy when ATP is broken down.

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15
Q

Why is ATP often called a ‘universal energy currency’?

A

because ATP provides energy in all cells in all reactions in all organisms

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16
Q

What is the role of ATP in protein synthesis?

A

ATP required for amino acid activation in the cytoplasm. (joining a specific AA to rNA)

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17
Q

What is the role of ATP in active transport?

A

ATP changes the shape of carrier proteins to move molecules against a concentration gradient. (alters the tertiary structure)

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18
Q

What is the role of ATP in secretion/bulk transport/exocytosis?

A

Packaging and transport of secretory products, like enzymes in vesicles.

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19
Q

What is the role of ATP in nerve transmission?

A

Sodium/ potassium pumps actively transport ions across the axon membrane.

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20
Q

What is the role of ATP in muscle contraction?

A

Energy is required for contraction of muscle fibres

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21
Q

What is the role of ATP in DNA replication (semi conservative replication)?

A

Synthesis of DNA from nucleotides during DNA replication at interphase.

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22
Q

How is ATP formed?

A

-The enzyme ATP Synthase combines ADP (adenosine diphosphate) and Pi (inorganic phosphate) in a condensation reaction.
-This requires an input of energy (30.6 kJ mol-1) in an ENDERGONIC reaction.

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23
Q

What is the addition of Pi to ADP called?

A

phosphorylation

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24
Q

What does condensation do when forming atp?

A

takes out water and forms a bond which is very high energy

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25
How is ATP hydrolysed?
-The enzyme ATPase hydrolyses the terminal phosphate bond releasing a small packet of energy (30.6KJ mol-1) in an EXERGONIC reaction. -This forms ADP and Pi .
26
How are the properties, structure and formation of ATP linked to its role in cells?
1. The hydrolysis of ATP to ADP releases immediate energy. The hydrolysis of glucose takes much longer and involves many intermediate reactions. 2. Only one enzyme is needed to release energy from ATP, whereas many are needed in the case of glucose. 3. ATP releases energy in small packets when and where it is needed. 4. ATP is the universal energy currency in many reactions in all living organisms. 5. ATP is easily transported across membranes.
27
What are the 4 stages that the breakdown of a molecule of glucose to carbon dioxide and water in respiration involve?
1.Glycolysis- Cytoplasm 2. Link Reaction- Mitochondrial matrix 3. Krebs Cycle- Mitochondrial matrix 4. Electron Transport Chain- Inner mitochondrial membrane (cristae)
28
What happens during respiration? (redox reactions)
-During respiration, glucose is broken down in a series of reactions to synthesise ATP. -At various stages in this process, hydrogen atoms are removed from intermediate compounds and split into protons and electrons
29
What are examples of redox reactions in respiration?
In respiration, two co-enzymes act as hydrogen carriers: 1. NAD+ is reduced to form reduced NAD (NADH/H+) 2. FAD is reduced to form reduced FAD (FADH2)
30
How does glucose emerged the cell cytoplasm in glycolysis?
Facilitated diffusion through an intrinsic carrier protein. (large polar molecule)
31
How are ATP molecules synthesised in glycolysis?
-using energy derived from the breakdown of a substrate, which donates an inorganic phosphate. -This inorganic phosphate combines with ADP to form ATP. This is known as substrate level phosphorylation.
32
What is energy released from the breakdown of a substrate (e.g. oxidation of triose phosphate) used to do?
-transfer a phosphate from a donor to combine with ADP to make ATP (no electrochemical gradient)
33
How much ATP is produced per glucose molecule in glycolysis?
Reduced NAD produced = 2 ATP Gross Produced = 4 Used = 2 Net total produced = 2
34
What is the process of glycolysis?
-Glucose (6C) is phosphorylated to form hexose phosphate (6C)- requires the addition of 2 ATP molecules. -Hexose phosphate (6C) splits into two triose phosphate molecules (3C). -Each triose phosphate molecule is oxidised to pyruvate (3C). This means that hydrogen is removed by a dehydrogenase enzyme in a dehydrogenation reaction. The hydrogen is accepted by NAD forming reduced NAD. -The production of pyruvate from triose phosphate also results in the phosphorylation of 2 ADP molecules to produce 2 ATP – this is substrate level phosphorylation. -Overall, in glycolysis 2 reduced NAD and 2 pyruvate are produced. There is also a net gain of 2 ATP molecules as 4 ATP molecules were produced but 2 ATP were required in the first stage of the pathway to phosphorylate glucose.
35
Glycolysis results in a small yield of chemical energy in the form of ATP. What other form of energy is also released?
Heat/Thermal
36
How is the link reaction initiated?
Pyruvate (pyruvic acid) diffuses from the cytoplasm into the mitochondrial matrix where the link reaction occurs
37
When does glycolysis only occur?
In the presence of O2
38
Why is pyruvate provided as a respiratory substrate for mitochondria and not glucose? (link reaction)
-Glucose can only be hydrolysed in the cytoplasm during glycolysis. -Pyruvate can enter (by facilitated diffusion) the mitochondrion for the link reaction.
39
How many times does the link reaction go around for each glucose molecule?
2x
40
Per glucose molecule how much Reduced NAD and CO2 are produced?
2 reduced NAD 2 CO2
41
What is the process of the link reaction?
-In the presence of oxygen, pyruvate diffuses from the cytoplasm into the mitochondrial matrix where the link reaction takes place: -Pyruvate (3C) is decarboxylated by a decarboxylase enzyme which removes one molecule of CO2. Pyruvate is also oxidised to acetate: dehydrogenase enzymes remove hydrogen which is accepted by NAD to form reduced NAD. Acetate (2C) is produced. -Acetate (2C) combines with coenzyme A to form acetyl Coenzyme A which enters Krebs Cycle. -Overall in the link reaction 2 molecules of CO2, 2 molecules of reduced NAD and 2 molecules of acetyl coenzyme A are produced per glucose molecule.
42
Six molecules of glucose enter glycolysis and are oxidised. How many acetate molecules would be produced at the end of the link reaction?
12
43
Why is it an advantage to have pyruvate as an intermediate compound in respiration?
-3C compound easily diffuses into the mitochondrion. -There are no carrier proteins for glucose on the membrane of a mitochondrion.
44
What is the role of coenzyme A?
Transports 2C acetate to the Krebs cycle.
45
How many times does the kreb’s cycle go round for each glucose molecule?
2
46
How many reduced NAD, CO2, reduced FAD and ATP produced by krebs are produced per glucose molecule?
Reduced NAD produced = 6 Carbon dioxide produced = 4 Reduced FAD produced = 2 ATP produced by substrate level phosphorylation = 2
47
What is the krebs cycle also known as?
citric acid cycle
48
What is the process of the krebs cycle?
-Krebs cycle liberates energy from carbon-carbon bonds to make ATP, reduced NAD (NADH/H+ and reduced FAD (FADH2). Carbon dioxide is also released as a waste product. -The acetate (2C) from acetyl coenzyme A combines with a 4C compound to form a 6C compound. Coenzyme A is regenerated and returns to the link reaction to collect another acetate. -A series of enzyme controlled reactions then takes place; there are two decarboxylation reactions and four dehydrogenation reactions per turn of the cycle. -The acetate which enters Krebs cycle is completely broken down to CO2 and water and the 4C compound is regenerated via 6C and 5C intermediates.
49
What happens to the coenzyme A after it has delivered acetate to Krebs cycle?
Coenzyme A is regenerated and returns to link reaction to collect more acetate
50
What is the fate of the NADH and FADH2 produced in Krebs Cycle?
delivers hydrogen to the ETC for synthesis of ATP by chemiosmosis
51
Name the molecule required for hydrolysis reactions to occur.
water
52
What is decarboxylation?
any chemical reaction in which a carboxyl group (-COOH) is split off from a compound as CO2. -Catalysed by decarboxylase enzymes.
53
What is dehydrogenation?
-a chemical reaction that involves the elimination of hydrogen. -It is catalysed by dehydrogenase enzymes.
54
What are examples of dehydrogenation in respiration?
Glycolysis - triose P to pyruvate, Link - pyruvate to acetate, Krebs - 6C-5C, 5C-4C, 4C-4C
55
What are examples of decarboxylation in respiration?
Link pyruvate to acetate, Krebs 6C-5C, 5C-4C
56
What is the final stage of respiration?
electron transport chain which takes place in the inner mitochondrial membrane.
57
Why is it an advantage for the inner mitochondrial membrane to be folded into cristae?
Increased SA for stalked particles so more ATP can be synthesised
58
What are 2 functions mitochondrial DNA?
Codes for its own replication Codes for enzymes involved in aerobic respiration
59
What happens in Oxidative phosphorylation?
-NADH and FADH2 get oxidised (lose H) at the etc chain -energy lost from e- build an electrochemical gradient used to combine ADP and Pi to ATP (ATP synthase) = chemi osmosis gradient
60
What is the process of ATP production at the inner mitochondrial membrane?
1. Reduced NAD and reduced FAD deliver their pairs of hydrogen atoms to the electron transport chain at the inner mitochondrial membrane. 2. The hydrogen atoms split into protons (H+) and electrons (e-). 3. The high energy electrons are transferred along carriers in the inner mitochondrial membrane along the electron transport chain, moving from high energy levels to lower energy levels. 4. The energy released during electron transport fuels the proton pumps. 5. Protons are pumped through channel proteins from the matrix to the intermembrane space. 6. The build up of protons in the intermembrane space forms an electrochemical gradient. 7. Stalked particles lining the cristae contain the enzyme ATP synthase. 8. Protons flow down their concentration gradient through an ion channel in ATP synthase. This is the only part of the membrane permeable to H+. 9. The flow of protons releases enough energy for the synthesis of ATP from ADP and Pi (catalysed by ATP synthase). 10.The production of an electrochemical gradient which results in the diffusion of protons through a proton channel in ATP synthase, fuelling the synthesis of ATP, is known as chemiosmosis. 11. Oxygen acts as the final electron acceptor; the electrons and protons combine with oxygen to form water. 4H+ + 4e- + O2  2H2O. 12. This method of producing ATP is called oxidative phosphorylation.
61
What is the final electron acceptor in aerobic respiration?
oxygen
62
How many ATP molecules are produced by oxidative phosphorylation?
-Reduced NAD (NADH/H*) generates 3 molecules of ATP because the carrier system involving NAD involves 3 proton pumps. -Reduced FAD (FADH,) generates 2 molecules of ATP because the carrier system involving FAD involves 2 proton pumps.
63
What is the PH change in the inter membrane space during chemiosmosis?
As protons (hydrogen ions) are pumped into the space the pH becomes more acidic (lower)
64
What is the ETC?
The movement of high energy electrons along electron carriers, releasing energy to fuel proton pumps
65
What is chemismosis?
Production of an electrochemical gradient resulting in the diffusion of protons through a proton channel past ATP synthase, fuelling the synthesis of ATP.
66
What is oxidative phosphorylation?
-The process by which ATP is produced at the electron transport chain on the inner mitochondrial membrane. Involves the oxidation of reduced NAD and reduced FAD.
67
How many molecules of ATP are produced from substrate level phosphorylation?
4
68
How many ATP molecules are produced from oxidative phosphorylation?
34
69
Suggest why cells may not actually produce 38 ATP molecules from one glucose molecule.
-In the absence of oxygen only glycolysis will occur producing a net gain of 2 ATP (anaerobic respiration using glycolysis only). -Some of the intermediate compounds of respiration may be used in biosynthetic pathways within cells.
70
Glucose catabolism during aerobic respiration is spread out over many reactions, suggest an advantage of this.
Energy is released in small packets rather than all at once which could release too much heat. Excessive increases in temperature could lead to denaturation of proteins in cells.
71
describe the structure of an enzyme molecule.
Enzyme – dehydrogenase, globular tertiary structured protein with specific 3D shape. Substrate – respiratory intermediates. Substrate complementary shape for enzyme active site.
72
Describe and explain the effects of temperature on pyruvate dehydrogenase enzymes within yeast cells. Refer to oxidation and reduction.
Astemp increases up to optimum the rate of reaction gradually increases. More kinetic energy – enzyme dehydrogenase and respiratory intermediates. More successful collisions/ESC More H removed by dehydrogenase in a shorter period of time (oxidation) More NADH/H+ is produced (reduction). An example of where dehydrogenation takes place e.g. glycolysis. As temp increases past the optimum rate of reaction has a steep decline. Dehydrogenase starts to denature - H bonds broken, change to tertiary structure and change in shape of active site Less H removed by dehydrogenase and so less NADH/H+ produced. Use of figures – e.g. optimum 37oC. Completely denatured at 63oC..
73
What is the definition of exogernic?
A reaction that releases energy e.g. from the hydrolysis of ATP.
74
What is the definition of endogernic?
A reaction that requires energy e.g. to produce ATP.
75
What is phosphorylation?
The addition of phosphate.
76
When is an electrochemical gradient created?
Created when protons H+ are pumped into a cavity.
77
What is an election carrier?
High energy electrons are passed from one to the next, releasing energy as they pass
78
What is a proton pump?
Actively transports protons against their concentration gradient
79
What is yield?
The total number of molecules produced in a reaction.
80
What is net gain?
total gained – that used.
81
What is substrate level phosphorylation?
-ATP molecules are synthesised using energy derived from the breakdown of a substrate, which donates an inorganic phosphate. -This inorganic phosphate combines with ADP to form ATP. Occurs during glycolysis + Krebs cycle.

A-level biology component 1 (+immunology) (8 decks)

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