Respiration Flashcards
(91 cards)
1
Q
What is respiration?
A
series of metabolic reactions where respiratory substrate molecules are metabolised to produce ATP molecules which can then be hydrolysed to release energy for energy requiring processes in cells
2
Q
What is a respiratory substrate?
A
any molecule that can be metabolised to produce ATP
3
Q
Why is glucose not very useful (why does it need to be respired)?
A
1 glucose molecule has a lot of chemical potential energy but not very useful because energy in 1 big package
4
Q
Why is ATP more useful than glucose?
A
- around 32 ATP molecules produced by resp
- high energy molecules but much more useful bc energy is in small packages
5
Q
respiration does not produce…
A
ENERGY, produces ATP
6
Q
ATP requiring processes e.g.?
A
- AT
- muscle contraction
- protein synthesis
- cilia movement
- bulk transport
- DNA rep
7
Q
Stages?
A
- Glycolysis
- link reaction
- Krebs cycle
- Oxidative Phosphorylation
8
Q
Glycolysis?
A
- splitting of glucose
- occurs in aerobic and anaerobic
9
Q
Size of ribosomes in mitochondria?
A
70s, needed for translation of mitochondrial proteins
10
Q
Why are there stalked particles in mitochondria?
A
- all along IMM
- ATP synthase molecules 1-2micrometer long
- H+ move through ATP synthase molecules by FD allowing synthesis of ATP
11
Q
why does mitochondria have DNA?
A
• contains genes for mitochondrial proteins e.g. ATP synthase
12
Q
cristae in mitochondria?
A
- folds
- inc SA
- for e- carrier proteins - OP
13
Q
membrane of mitochondria?
A
- inner membrane
- intermembranal space
- outer membrane
envelope
14
Q
inner mitochondrial membrane?
A
- folds to inc SA
- separates intermembranal space from matrix
- contains membrane proteins involved in OP
- H+ ion move thru ATP synthase
15
Q
intermembranal space?
A
provides a space for the build up of a H+ proton gradient
16
Q
outer mitochondrial membrane?
A
compartmentalises the link reaction, krebs cycke, and OP from cytoplasm of the cell
17
Q
glycolysis doesn’t occur in?
A
mitochondria, actually occurs in cytoplasm
18
Q
Steps in glycolysis?
A
Glucose
⬇ (ATP ➡ ADP + Pi)
hexose phosphate
⬇ (ATP ➡ ADP + Pi)
hexose bisphosphate
⬇
2 TP
⬇ (4ADP ➡ 4ATP), (2redNAD produced)
2Pyruvate
19
Q
Glucose to hexose bisphosphate is
A
phosphorylation
20
Q
triose phosphate to pyruvate is ?
A
oxidation, (2redNAD produced)
21
Q
how many ATP needed to start resp
A
2
22
Q
NAD?
A
- coenzyme
- H carrier
- takes part in reactions catalysed by dehydrogenases (takes H)
- when it gets reduced, gains 2 H atoms (2H+ + 2e-)
23
Q
reduction of NAD equation?
A
NAD + 2H+ + 2 e- ➡ NADH + H+
24
Q
The link reaction?
A
- happens in matrix
* links glycolysis and krebs cycle
25
Steps of link reaction?
```
2 Pyruvate (3C)
⬇ (2CO2 removed, decarboxylation reaction)
(H lost, dehydrogenation)
2 Acetate (2C)
⬇ ⬅ coenzyme A
2 Acetyl coenzyme A
⬇
2 Acetate
```
26
what happens to acetate?
combines with the coenzyme A (upwards arrow), fed into KC
27
How many acetates from 1 pyruvate?`
1
28
H that are lost are used to
reduce NAD
29
KC a.k.a
citric acid cycle or TCA
30
What enters the krebs cycle?
* acetyl coA combines with oxolacetate (4C)
* forming citrate (6C)
* goes off to collect more acetate
* Citrate then decarboxylated and dehydrogenated (oxidised)
* H combine with NAD to form redNAD and FAD to form redFAD
31
KC summary - per 1 turn ?
* 3 redNAD
* 2 CO2 produced
* 1 ATP
* redFAD
32
ATP produced from glycolysis and KC is
substrate level phosphorylation, OP contrasts
33
⭐ 2 TURNS OF KC PER
1 GLUCOSE
34
OP?
* ETC
* located within mitochondrial membrane, happens in IMM, IMS and matrix
* where the most energy required
35
OP?
* redNAD and redFAD give up their H to the ETC where the H are split into H+ + e- using energy from e- movement
* H+ are pumped (not AT) into IMS
* more H+ in IMS = diffusion gradient
* H+ move into matrix through ATP synthase, producing ATP
* -chemisosmosis
* O2 accepts e- from ETC - final electron acceptor
* O- + 2H+ -> H2O
36
OP is not?
substrate level phosphorylation
37
OP - if O is not available?
* If O2 not avbl to collect e-, e- is stuck
* traffic jam queue of NAD and FAD waiting to drop off H+
* causes shortage for krebs cycle
* prevents other stages
38
why do we not achieve the potential yield of ATP molecules?
* only get potentials if enough ADP + Pi in mitochondria
| * 25% of ATP made is used to transport ADP into mitochondria and ATP out into cell
39
how many ATPs produced in OP?
• 28, 32 in total from resp - 2 gained in KC and 2 in Gly
40
How many turns of KC for every glucose ?
* 2
* Glycolysis: 2 molecules of pyruvate formed
* make 2 molecules of acetyl coA
* so, for each molecule of glucose, 2 turns of krebs cycle
41
Other reasons why max theoretical yield of glucose of not achieved ?
* 38
* pyruvate has to be AT from cytoplasm into matrix
* ADP and Pi have to be AT from cytoplasm into matrix
* some H+ leak across IMM back into matrix
42
H+ ion movement thru ATP synthase is?
facilitated diffusion
43
Evid for chemisosmosis?
1. pH gradient, high in matrix - chemiosmosis
2. dinitrophenol causes IMM to be very leaky to H+. Mit treated with DNP produce less ATP - H+ can bypass ATP synthase so less ATP made
3. isolated thylakoids can be made to produce ATP
44
When there's no O2?
* O cannot accept electron
* so ETC stops
* redNAD can't be reoxidised so
* Krebs cycle stops
* pyruvate not made so acetyl coA not made
45
Why should glycolysis no longer continue?
• redNAD made can no longer release H and be recycled
46
2 pathways of anaerobic resp?
* ethanol pathway (yeast and some bacteria)
| * lactate pathway
47
Ethanol pathway?
* 2 pyruvate produced in pyruvate
* 2Pyruvate decarboxylated into 2 Ethanal by pyruvate decarboxylase
* Ethanal reduced from ethanal into 2 ethanol by ethanol dehydrogenase
* redNAD to oxNAD - oxNAD regen so glycolysis can continue
48
ethanol pathway - ATP yield & plants?
* low ATP yield
| * occurs in waterlogged plants bc they're O2 deprived
49
lactate pathway?
* all mammals
* only 2 mols of ATP produced
* glycolysis continues
* but pyruvate is reduced to lactate generating oxNAD so glycolysis can continue
50
what happens to pyruvate in lactate pathway?
Pyruvate ➡ lactate by lactate dehydrogenase
| oxNAD made
51
in both anaerobic systems ?
* there is a toxic build up
| * if toxic levels of ethanol, reaction can be reversed
52
how do we deal w lactate?
* travels in blood to liver
* where it's combined with O2 (the oxygen debt!) to form CO2 and H2O - 20% oxidised
* lactate to pyruvate in liver
* if there's a lot: pyruvate ➡ glucose➡glycogen
53
which reactions happen to keep glycolysis going?
* mammals: lactate pathway
| * yeast: ethanol pathway
54
what are the disadvantages of anR comp to AR?
* lactate and ethanol r toxic
* lactate causes pain, can't happen for long
* ethanol kills yeast cells if closed envir
* 2 ATP produced in lactate
55
what happens to the lactate when ATP demand returns to a level where it can be met by AR?
* lactate ➡ pyruvate in the liver
* pyruvate enters link reaction
* pyruvate can b converted to glycogen for storage
56
Removal of lactate also needs?
* to become oxidised back to pyruvate, lactate also needs oxNAD to be reduced
* oxNAD supplied by OP when AR restarts
57
What is a resp substrate?
substance used to produce ATP in a cell by respiration
58
How can triglycerides be respired?
* hydrolysed to FA
* which enters KC via acetyl coA
* and glycerol which ➡ pyruvate
59
lipids & resp?
lipids store and release about 2x as much energy as carbs
60
how can proteins be respired?
* proteins are hydrolysed to AA
* AA have to be deaminated at hepatocytes - ornithine cycle
* requires ATP, reducing net ATP production
61
how is RQ measured?
using a respirometer
62
Where does each RS enter resp?
* glycerol in TP (gly)
* FA in acetyl coA
* lactate at pyruvate
* AA from proteins at pyruvate or KC
63
energy content in decreasing order?
lipids > alcohol > carbs/ proteins
64
oxidation involves ?
dehydrogenation - loss of H atoms
65
why do different RS have diff energy densities?
* ATP is obtained from RS thru oxidation forminh redNAD
* involves dehydrogenation
* if a molecule has proportionally more H atoms, then more redNAD molecules are formed and more ATP molecules can be synthesised in OP
* also means more O2 needed to accept e-s at the end of ETC - so lipids have RQ of >1
66
What can the RQ value show?
* what is being respired
| * whether or not anR is occuring
67
RQ equation?
vol of CO2 out (in a set time)/ vol of O2 in (in a set time)
68
RQ values ?
carbs: 1
protein: 0.8-0.9
lipids: 0.7
69
RQ general?
* can be volume, n, molecules
| * if RQ values are high, more CO2 is being produced than O2 is being used, indicating high levels of anR
70
if RQ is over 2 ?
* ethanol pathway
| * some O2 in the yeast may be taken up
71
RQ for lactate pathway?
• can't calc
72
Why is the RQ for complete anR of glucose in yeast infinite?
2CO2 produced but none used -2/0 = infintity
73
why can the RQ for anR of glucose in humans can't be calc?
no O2 used and no CO2 produced
74
Respirometer: bubble movement?
* when O2 taken in, would move ⬅ towards the thing
| * when CO2 exhaled (more than taken in) moves ➡
75
when something is respiring (taking in O2) as much as it is exhaling CO2?
• bubble would move the same amount in each direction so no overall movement: RQ is 1
76
respirometer: why does the exp need to be done 2x?
* with KOH/ sodalime - absorb CO2
* more movement towards organism
* record movement - will tell us the O2 consumption
* repeat w/o absorber - to get CO2 production along (minus the values)
77
if RQ is >1?
could be respiring anR, producing more CO2 than O2 consumption
78
Glycolysis is?
substrate level phosphorylation
79
Why is ATP needed in glyolysis?
* addition of phosphate group to glucose destabilises glucose bc P = polar which makes it more likely to undergo the following reactions
* glucose = stable so ATP needed
80
what is the point of the KC?
To make red coenzymes
81
KC products?
* 3redNAD, 1red FAD for acetyl
| * 6 redNAD, 1 redFAD, 1 ATP per glucose
82
if ETC stops, how are other stages affected?
* NADH and FADH build up
* this is bc they can't give up e- bc the 1st e- carrier is already occupied w e-
* means no oxNAD and oxFAD regen
* so KC will stop ^ are needed there
* link reaction stops - needs NAD and coA
* glycolysis continues
83
when the coenzymes are reoxidised in OP?
can go back to KC and accept more H+.
84
Respirometer: why is a gauze platform used?
• stops organisms from falling into the liquid
85
Respirometer: why is a screw clip used?
seal apparatus
86
Respirometer: why is a syringe used?
to reset position of liquid in capillary tube
87
Respirometer: 3 way tap?
• to top up O2 to inc volume
88
Respirometer: why are glass beads used in the control tube?
to ensure exactly the same V as respiring organisms
89
Respirometer: why is a capillary U tube used?
to measure CO2 production and O2 consumption
90
Respirometer: why is a control tube used?
* Cancels out the effect of temp in respirometer
* same V of air in each tube because same vol of organisms and beads
* so if T inc, air inside both tubes expands so the liquid is pushed up and down by the same degree - doesn't move
91
effect of T on respirometer?
* causes gas to expand
* which causes the movement of fluid
* but fluid should only move due to O2/ CO2
