Respiration Flashcards
(102 cards)
1
Q
What does metabolism refer to?
A
All the reactions of the organism.
2
Q
What sort of pathway is respiration?
A
It is a metabolic pathway which is controlled by enzymes (catabolic). Energy rich macromolecules are broken down i.e. glucose and fatty acids to release energy: some is trapped as chemical energy in ATP and some is released as heat energy.
3
Q
What high energy bonds are broken down?
A
C-C
C-H
C-OH
4
Q
What happens when the high energy bonds are broken down?
A
Lower energy bonds are formed and the difference is released and used to attach a phosphate group to ADP to produce ATP.
5
Q
What is oxidative phosphorylation?
A
It’s the energy from the oxidation and reduction reactions to make ATP which is released as a transfer of electrons along a chain of electron carrier molecules.
6
Q
Where does oxidative phosphorylation occur?
A
On the inner membrane of the mitochondria in aerobic respiration
7
Q
What is substrate phosphorylation?
A
It occurs when phosphate groups are transferred from donor molecules or when enough energy is released so that ATP combined to a phosphate group.
8
Q
What is aerobic respiration?
A
It’s the release of large amounts of energy made available as ATP from the breakdown of molecules with oxygen as a terminal electron acceptor.
9
Q
What is anaerobic respiration?
A
The breakdown of molecules in the absence of oxygen releasing little energy making a small amount of ATP by substrate level phosphorylation.
10
Q
What energy does respiration provide for?
A
Condensation reactions of ADP to ATP, energy for this reaction comes from the chemical energy stored in glucose.
11
Q
What is each stage of respiration catalysed by?
A
A specific enzyme
12
Q
Catalyisation of enzymes are examples of what sort of reaction?
A
Oxidation (loss of H)
Reduction (gain of H)
13
Q
What do you coenzymes do?
A
They assist are the enzymes in oxidation and reduction reactions. Co enzymes are continuously cycled.
14
Q
What are the co-enzymes used in respiration?
A
NAD
FAD
Co- enzyme A
15
Q
What happens if the coenzymes are reduced?
A
They are use in the final stage of respiration (oxidative phosphorylation) which produces ATPThey are use in the final stage of respiration (oxidative phosphorylation) which produces ATP
16
Q
What is NAD used in?
A
Glycolysis, link reaction, Krebs cycle, anaerobic respiration (lactate pathways)
17
Q
What is NAD?
A
Dinucleotide.
Derived from vitamin B.
Niacinamide.
NAD (OX) NADH (RED)
18
Q
What is coenzyme A?
A
It derives from vitamin B
19
Q
What is CoA used in?
A
It’s used to transfer product of glycolysis into the mitochondria for the link reaction. It carries the acetyl groups created through oxidation during the link reaction onto the Krebs cycle.
20
Q
What is FAD?
A
Derives from B2.
Made from adenine, ribose, two phosphate groups.
FAD –> FADH
21
Q
Where is FAD used?
A
In the Krebs cycle
22
Q
What are the four stages of aerobic respiration?
A
Glycolysis, link reaction, Krebs cycle, oxidative phosphorylation
23
Q
Where does glycolysis occur?
A
In the cytoplasm
24
Q
Where does the link reaction occur?
A
In the mitochondrial matrix (pyruvate diffuses from the cytoplasm to the matrix)
25
Where does the Krebs cycle occur?
In the mitochondrial matrix
26
Where does oxidative phosphorylation occur?
On the inner mitochondrial membrane (Cristal)
27
What does glycolysis generate?
Pyruvate, ATP, NADH
28
What does LR generate?
Acetyle CoA
29
What does KC generate?
CO2, NADH, FADH
30
What does oxidative phosphorylation generate?
ATP from ADP + Pi
31
Glycolysis facilitate what pathways?
Aerobic and anaerobic
32
Where does glycolysis occur?
It occurs in the cytoplasm as glucose is too large to pass through the membrane, the enzymes are found in the cytoplasm.
33
What process is glycolysis?
Anaerobic
34
What does glycolysis produce?
2 pyruvate, 2 NADH, 2 (NET) ATP and heat energy
35
Use a flow chart to show glycolysis?
Glucose (6C) --> Hexose biphosphate ---> 2 Triose phosphate (TP)(3C) --> 2GP (3C) --> 2 pyruvate (3C)
36
Why is glucose is phosphorylated?
It lowers the activation energy for the enzyme controlled reactions. It becomes polar so less likely to diffuse out of the cell.
37
Show the equation for glycolysis?
Glucose + 2NAD + 2ADP +2Pi --> 2 Pyruvate + 2NADH + 2ATP + heat energy
38
Show the equation for LR?
pyruvate + CoA + NAD --> Acetyl CoA + CO2 + NADH
39
What does one glucose molecule in the link reaction produce?
2NADH, 2 Acetyl CoA, 2CO2
40
What two enzymes are used in the link reaction?
Dehydrogenase and decarboxylase
41
What happens when producing acetate?
The pyruvate is decarboxylated (oxidative decarboxylation of pyruvate) by decarboxylase. A molecule of CO2 is removed. Dehydrogenated (dehydrogenase) the NAD accepts a H --> NADH
42
What does acetate combine with?
It combines with CoA which makes as acetyl CoA which enters the Krebs cycle.
43
Describe the Krebs cycle?
The acetate is offloaded from CoA and combined with the a 4C molecule to form a 6C compound. The CoA is regenerated.
The 6C is dehydrogenated making NADH, decarboxylated to make CO2 and a 5C molecule.
The 5C molecule is decarboxylated and dehydrogenated to form a 4C, there's enough energy to phosphorylate ADP+ Pi--> ATP (SLP).
The 4C compound is dehydrogenated where FAD becomes FADH.
The other 4C compound is further hydrogenated and regenerated to make a 4C molecule, where another molecule of NADH is produced.
44
How many decarboxylation and dehydrogenation reactions occur in the KC?
```
2 Decarboxylation (removal of C from COOH group as CO2)
4 Dehydrogenation (removal of hydrogen)
```
45
What happens when the acetate fragment is broken down?
Its broken down to CO2, water and the 4C is regenerated via 6C and 5C intermediated. H2O is fed in at three reactions
46
Whats the function of the KC?
It is a means of liberating energy from carbon bonds via reduced intermediates to provide ATP, NADH, FADH with CO2 released.
47
What are the products per turn?
1 ATP
3 NADH
1 FADH
2CO2
TWO TURNS PER GLUCOSE
48
What are the products of the KC per glucose?
2 ATP
6 NADH
2 FADH
4 CO2
49
Where does oxidative phosphorylation occur?
Inner mitochondrial membrane
50
What stage is OP?
Its the final stage of aerobic respiration, with the involvement of 3 proton pumps (3 pumps associated with NADH and 2 pumps associated with FADH)
51
What is the final electron acceptor?
Oxygen is the final electron acceptor of the ETC
52
What happens to the NADH and FADH in OP?
They deliver their airs of hydrogen atoms to the electron transport system in the inner mitochondrial membrane, which splits into H+ and e-. The electrons pass along the chain of electron carriers and then donated to oxygen (final e- acceptor). When the electrons are transferred to O2, H+ from the matrix are also accepted to produce water.
1/2 O2 + 2e- + 2H+ --> H2O
53
What is chemiosmosis?
As electrons flows along the ETC, energy is released to pump the H+ across the intermembrane space. Building up the H+/ electrochemical/ pH gradient (conc is higher in the inter membrane space than the matrix). Protons flow back into the matrix via ATP Synthase generating ATP.
54
What is OP?
Its the formation of ATP by ADP + Pi in the presence of oxygen (final electron acceptor in the ETC) which removes protons and electrons (reduces O2) to form water.
55
What happens in the presence of cyanide
This is a non competitive respiratory inhibitor of the final electron acceptor in the ETC, H+ and e- can't be transferred to water. They accumulate destroying the H+ gradients. ATP synthase stops working and the cells die quickly.
56
Summarise oxidative phosphorylation?
1. Hydrogen atoms are removed from NADH to NAD by dehydrogenase and split into protons and electrons (FADH is oxidised further down etc).
2. Electrons enter the ATC and pass down a series of electron carriers in the inner membrane.
3. Energy released from ETC pumps H+ into the inter membrane space creating a H+ gradients.
4. The end of mitochondrial membrane is impermeable so H+ can only return to the matrix through ATP synthase (proton motive force) resulting in ATP formed in chemiosmosis (ADP is phosphorylated).
5. At the end protons and electrons are accepted by oxygen (final electron acceptor) to form water.
57
What does ATP production require?
Oxygen
58
What does the complete oxidation of one glucose yield produce?
10NADH
2FADH
In the mitochondrial matrix
59
What is the energy yield for NADH?
3 ATP
60
What is the energy yield for FADH?
2 ATP
61
What happens if there is no oxygen present?
The electron transport can't function (no oxygen to remove H from NADH and produce water).
No oxidative phosphorylation.
No ATP formed.
NADH (and FADH) can't be re-oxidised and no NAD is regenerated to pick up hydrogen.
LR and KC can't take place
62
What stage of respiration can take place in aerobic respiration?
Glycolysis
63
What is fermentation?
It's an anaerobic process which follows glycolysis to continue ATP production until oxygen is available. Some organisms inhabit anaerobic conditions like bacteria and yeast.
64
What are the two types of fermentation?
```
Lactic acid (lactate) fermentation.
Alcohol (ethanol) fermentation
```
65
What is lactic acid fermentation?
It's a series of anaerobic reactions in which pyruvate uses NADH to form lactic acid and NAD. The NADH formed in glycolysis is oxidised when to pyruvate are reduced to lactate. This is because pyruvate is not transferred to the mitochondria and finally oxidised to CO2 but reduced to lactate.
66
What are formed in lactic acid fermentation?
NAD is regenerated in glycolysis and fermentation.
| Two ATP formed in glycolysis but none in fermentation.
67
What happens when lactic acid builds up?
A buildup in the muscles and causes muscle fatigue. Lactic acid leaves the muscles and goes to the liver to be converted back to pyruvate.
68
What is alcohol fermentation?
One glucose breaks into two pyruvate producing 2 ATP and 2NADH.
2 pyruvate are then decarboxylated by decarboxylase into two ethanal molecules and 2CO2
2 ethanal molecules are reduced to 2 ethanol by using H from NADH
69
What are formed in ethanol fermentation?
NAD regenerated
| Yield 2 ATP from glycolysis
70
Is ethanol fermentation irreversible or reversible?
It is irreversible even if oxygen must be present ethanol is not broken down accumulates in the cells which could rise to toxic levels.
71
How many terms of the Krebs cycle is for one glucose molecule?
2
72
How many ATP are produced from oxidative phosphorylation (conversion from NADH and FADH)?
34
73
How many ATP are produced from substrate level phosphorylation (from ADP + Pi)?
4
74
How many total molecules of ATP are produced per glucose?
38
75
Why is the theoretical total of ATP molecules not the actual total?
ATP is used to move pyruvate, ADP, NADH and FADH into the mitochondrial matrix.
A proton gradient may be compromised by a proton leakage across the inner mitochondrial membrane rather than passing through ATP synthase.
Molecules may leak through membranes (leaky membranes)
76
On average how many ATP molecules does a cell produce per glucose respired?
30-32
77
How much energy is required to make one mole of ATP?
30.6 KJ
78
What's the formula for efficiency of ATP production?
energy made available through ATP/ energy released in combustion x100
79
What is the efficiency of ATP production in aerobic respiration?
40.4%
80
What is the efficiency of ATP production in anaerobic respiration?
2.1%
81
Why is there only 2 ATP molecules produced in anaerobic respiration?
Without ATP synthase associated with the electron transport system only two ATP molecules per glucose are formed which is during glycolysis by substrate level phosphorylation.
82
What happens to the pyruvate in anaerobic respiration?
It is reduced to ethanol or lactate (it stays in the cytoplasm, NOT moved to the mitochondrion). The two hydrogens are released and the conversion of glucose to pyruvate, reduces NAD and is given up again in the formation of ethanol or lactate.
83
What is the respiratory substrate?
An organic molecule which can be oxidised to produce usable energy in the form of ATP.
84
What happens at the Krebs cycle?
It is where the metabolic pathways of carbohydrates, lipids and proteins can feed into it and some cases fat and proteins can be used as respiratory substrates.
85
Why is acetyl-CoA a significant molecule?
As it links the metabolism of glucose, fatty acids and amino acids
86
What are the respiratory substrates?
Carbohydrates - its the only substrate in some tissues e.g brain cells and RBC
Lipids
Proteins
87
When is lipids used as a respiratory substrate?
It is when carbohydrates in the body i.e. glycogen and glucose is low. As fat provides an energy store it is hydrolysed into fatty acids and glycerol.
88
What happens to the fatty acids in the lipids?
They are oxidised to produce to 2C acetate fragments which are fed into the Kreb cycle as acetyl CoA.
89
What do you longer fatty acid chains have?
More carbon atoms so more CO2 is produced if muscles were to respire fat more CO2 would be produced than could be removed.
More hydrogen atoms so more NADH so more ATP produced. Tissues with a high blood supply respire more fat as a large amount of ATP is produced to be transported around the body.
With more hydrogen atoms more metabolic water can be produced
90
What happens to the glycerol in the lipids?
It is phosphorylated with ATP, dehydrogenated with NAD and converted into a 3C sugar (TP) and intermediate of glycolysis. It's converted to pyruvate and fed into the KC via LR
91
When is proteins used as a respiratory substrate?
When dietary energy supplies are inadequate. In prolonged starvation tissue protein is mobilised to supply energy. Heart muscle and kidney tissue breakdown to release protein.
92
How are proteins used as respiratory substrates?
They are hydrolysed into their constituent amino acid which are deaminated in the liver forming a keto acid and ammonia. The amino group is converting to urea and excreted. Some keto acids are fed into glycolysis (e.g pyruvate) and others are fed into the KC. The residue carboxylic acid is converted into acetyl coenzyme A, pyruvate or other intermediates.
93
What is the function of the mitochondria?
Site of aerobic respiration which synthseises ATP
94
Give the structure of the mitochondria?
They have an inner and outer phospholipid membrane ie mitochondrial envelope.
Outer membrane is smooth, the inner is folded into cristae to give the inner membrane a large SA.
The inter-membrane space (between the inner and outer membrane).
The matrix is enclosed by the inner membrane.
The matrix consist of a mixture of proteins and lipids. Contains 70 S ribosomes and loops of mitochondrial DNA.
95
What happens at the inner membrane space?
Protons are pumped into the space using energy released by electron transport. Protons flow back into the matrix via ATP synthase generating ATP.
96
What happens at the matrix?
It contains enzymes for LR and KC.
| Hydrogen passes to ETC and CO2 is excreted.
97
What happens at the cristae?
The folding is provide a large internal surface area, the membrane contains the ETC and stalked particles (ATP synthase).
98
What is the mitochondrial envelope?
The double membrane which surrounds the mitochondria.
99
Describe the mitochondria outer membrane?
It has a similar protein to phospholipid ratio to eukaryotic plasma membranes.
It contains numerous integral membrane proteins called Porins which contain an internal channel permeable to molecules of 5000 daltons or less. Larger molecules can only transfers the outer membrane by active transport i.e. proteins.
100
What are the three types of functions that the proteins in the mitochondria in a membrane have?
1. Oxidation reactions of the respiratory chain i.e. electron carriers.
2. ATP synthase uses a proton gradient to make ATP.
3. Transport proteins which regulate the passage of metabolites in and out of the matrix.
101
Why is the inner membrane highly impermeable?
It doesn't contain Porins so almost all ions and molecules require special membrane transporters to enter and exit the matrix.
102
Where is the membrane potential?
Across the inner membrane.
