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M104 T2 > M104 T2 L3 > Flashcards

M104 T2 L3 Flashcards

1
Q

Why is pyruvate useful?

A

bc it can turn into whatever molecule the cell needs it to be

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2
Q

Which enzyme helps pyruvate turn into lactase?

A

lactase dehydrogenase

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3
Q

What can pyruvate turn into?

A

lactase
oxaloacetate
alanine
acetyl-CoA

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4
Q

Which enzyme helps pyruvate turn into oxaloacetate?

A

pyruvate carboxylase

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5
Q

Which enzyme helps pyruvate turn into alanine?

A

alanine aminotransferase

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6
Q

Which enzyme helps pyruvate turn into acetyl-CoA?

A

pyruvate dehydrogenase complex

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7
Q

In what conditions does pyruvate turn into acetyl-CoA?

A

aerobic conditions

with the enzyme pyruvate dehydrogenase complex

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8
Q

What happens to pyruvate under aerobic conditions when turning into acetyl-CoA?

A

it is oxidised

it is completely degraded

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9
Q

Where in the cell does pyruvate turn into acetyl-CoA?

A

in the mitochondria

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10
Q

Where in the cell does glycolysis occur?

A

in the cytosol

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11
Q

In what conditions does glycolysis occur?

A

aerobic and anaerobic conditions

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12
Q

Where does pyruvate have to move from in the cell to turn into acetyl-CoA?

A

was made in the cytosol

has to move to the mitochondria

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13
Q

Where does the TCA cycle occur?

A

in the mitochondria

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14
Q

What are other names for the TCA cycle?

A

Krebs cycle

citric acid cycle

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15
Q

What is gained from the TCA cycle?

A

energy is produced

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16
Q

What can FAs be activated by?

A

the addition of an acyl group

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17
Q

How are activated FAs transported into the mitochondria?

A

via carnitine shuttles

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18
Q

What happens to activated FAs in the mitochondria?

A

they are used to generate acetyl CoA

this enters the TCA cycle

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19
Q

How is pyruvate transported into a mitochondrion?

A

via the MCP-2 carrier protein embedded in the mitochondrial membrane in aerobic conditions

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20
Q

What is the name of the reaction by which pyruvate is converted into acetyle CoA?

A

oxidative decarboxylation

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21
Q

What does pyruvate turn into after oxidative decarboxylation?

A

Acetyl CoA

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22
Q

What is the equation by which pyruvate is converted into acetyl CoA?

A

Pyruvate + CoA + NAD+

acetyl CoA + CO2 + NADH + H+

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23
Q

Is the oxidative decarboxylation of pyruvate reversible?

A

no
the reaction is irreversible
acetyl CoA can’t turn back into pyruvate

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24
Q

How many carbons are in pyruvate?

A

three C

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25
How many carbons are in acetyl CoA?
two C
26
What two stages of metabolism are linked by the oxidative decarboxylation of pyruvate?
links glycolysis and the TCA cycle
27
What is the role of the PDH complex?
to convert pyruvate to acetyl-CoA
28
What does a PDH complex consist of?
3 enzymes | 5 co-enzymes
29
Why is the TCA cycle known as a final COMMON pathway for the oxidation of fuel molecules?
bc it doesn't matter which metabolic fuel is being used, so whether it's a glucose or lipids or proteins all of them end up in the TCA cycle
30
How many steps are in the TCA cycle?
8 steps
31
What happens overall in the TCA cycle?
acetyl residues from acetyl CoA | they are oxidised to co2
32
What is the formula for acetyl residues?
(CH3-CO-)
33
What is the role of reducing equivalents?
to transfer one electron in redox reactions
34
Where are the reducing equivalents transferred to? What do they form?
NAD+ or FAD to form NADH and FADH2
35
Why is the generation of NADH and FADH2 useful?
bc later on they will be transferred to the respiratory chain and used to generate ATP
36
What happens overall in the TCA cycle carbon-wise?
a 4C unit condenses with a 2-C unit. as the cycle goes on, 2Cs leave the cycle in the form of two CO2 mlcs the 4-C unit is regenerated
37
How many redox reactions occur through one TCA cycle?
four redox reactions
38
What substances are produced for each molecule of acetyl CoA entering the TCA cycle?
NADH x3 CO2 x2 FADH2 GTP (directly makes ATP)
39
What happens to the GTP molecule produced from one TCA cycle?
it goes on to directly generate a molecule of ATP
40
What are the eight different intermediates of the TCA cycle?
``` 1 - citrate 2 - isocitrate 3 - a-ketoglutarate 4 - succinyl CoA 5 - succinate 6 - fumerate 7 - L-malate 8 - oxaloacetate ```
41
How can you remember the eight intermediates of the TCA cycle?
A Certificate In Kama Sutra Should Further My Orgasm | After Class I Keep Some Specific Facts More Or-less
42
Of the eight enzymes involved in the TCA cycle, which three do you need to know?
1 - citrate synthase 3 - isocitrate dehydrogenase 4 - a-ketoglutarate dehydrogenase
43
Why are there only three enzymes of the eight in the TCA cycle that you need to know?
they are very important regulatory points of control for the TCA cycle their activity is controlled IOT control the speed of the TCA cycle
44
Which reaction in the TCA cycle does citrate synthase catalyse?
condensation reaction | reaction 1
45
What happens during the condensation reaction (reaction 1) of the TCA cycle?
oxaloacetate + acetyl CoA < citrate
46
Which reaction in the TCA cycle does isocitrate dehydrogenase then a-ketoglutarate catalyse?
iso - reaction 3 | aket - reaction 4
47
Which enzyme in the TCA cycle is part of the respiratory chain?
succinate dehydrogenase
48
At which two points of the TCA cycle is the flow of C-atoms TIGHTLY regulated at?
when pyruvate is converted into acetyl-CoA (under PDH enzyme control) the entry of acetyl-CoA into the TCA cycle (citrate synthase reaction)
49
At which additional lesser two points of the TCA cycle is the flow of C-atoms regulated at?
at the isocitrate dehydrogenase reaction | at the a-ketoglutarate dehydrogenase reaction
50
What happens if the E levels in a cell are high?
the activity of the TCA cycle will be inhibited
51
What molecules in high levels indicate the presence of high E levels in a cell?
ATP acetyl CoA FAs NADH
52
What molecules in high levels indicate the presence of low ATP levels in a cell?
AMP (present when ATP has been used up) CoA NAD+ Ca 2+
53
Why can calcium ions increase the rate of the TCA cycle?
they stimulate muscle contraction | they act as second messengers in some cells
54
What are alternative sources of acetyl CoA (other than glucose)?
FAs | amacs (less common)
55
Why are intermediate compounds of the TCA cycle constantly being replenished?
bc they have other biological roles in their cells
56
How are the intermediate compounds of the TCA cycle replenished?
via anaplerotic reactions
57
What is the role of anaplerotic reactions?
to maintain the concentrations of TCA cycle intermediates so that the cycle can function efficiently
58
How many turns of the TCA cycle occur from one glucose mlc (6C)?
two turns, so twice the amount of products than from just one mlc of acetyl CoA (3C)
59
What happens to the products of the TCA cycle that have been reduced in the process?
they are re-oxidised by the electron transport chain
60
When NADH is produced by glycolysis, where is it located and where does it need to go?
located - in the cytoplasm, this is where glycolysis occurs | going - the mitochondrial inner membrane, this is where the electron transport chain occurs
61
Why can't NADH get across the mitochondrial inner membrane?
the inner membrane is impermeable to NADH | there's no carrier in the membrane to transport NADH across
62
What happens to the NADH product of glycolysis?
shuttles transfer two electrons from each NADH mlc into the mitochondria rather than transferring the NADH itself
63
When NADH is produced by glycolysis, why does it need access to the mitochondrial inner membrane?
this is where the electron transport chain occurs | the NADH needs to be re-oxidised
64
What are the two types of shuttles involved in giving NADH electrons from the electron transport chain?
the glycerol-3-phosphate shuttle | the malate-aspartate shuttle
65
What areas is the glycerol-3-phosphate shuttle especially prevalent in?
the brain and muscle
66
What areas is the malate-aspartate shuttle especially prevalent in?
in the liver and the heart
67
What is the role of shuttles?
to give NADH e-s to the electron transport chain and regenerate NAD+ if the G3P shuttle is used, 1.5 mols of ATP is produced if the MAS shuttle is used, 2.5 mols of ATP is produced
68
What does the amount of ATP produced from shuttles depend on?
the type of shuttle used
69
What is DHAP reduced to and how?
G3P by accepting electrons from NADH | at the same time, NADH is oxidised back into NAD+
70
The redox reaction involving the reduction of DHAP and the oxidation of NADH is catalysed by what enzyme?
G3P dehydrogenase
71
What is special about G3P?
this molecule is able to diffuse into the inter membrane space of mitochondria
72
What happens to G3P once it is in the inter membrane space of mitochondria?
is oxidised back into DHAP by donating its two electrons to FAD
73
What is FAD reduced to?
FADH2
74
What happens to the DHAP once it has been converted from G3P?
it is able to diffuse back into the site of the cytosol | the process starts again
75
What is the effect of FAD turning into FADH2?
the FADH2 goes through the electron transport chain and results in the production of 1.5 M of ATP
76
Overall what happens in the G3P shuttle reactions?
a molecule of NADH / FADH2 transfers electrons into the mitochondria via a G3P shuttle 1.5 M of ATP is produced
77
What does the malate-aspartate shuttle involve?
two pools of NADH and NAD+, one in the mitochondrial matrix and the other in the cytosol
78
How does the process of the malate-aspartate shuttle start?
oxaloacetate in the cytosol accepts electrons from NADH and is reduced to malate
79
What happens to NAHD once it has donated electrons in the malate-aspartate shuttle?
it is oxisised back to NAD+
80
In the malate-aspartate shuttle, what is oxaloacetate converted into? What happens to it?
aspartate transported out of the mitochondria again in exchange for a molecule of glutamate once in the cytosol it turns back into oxaloacetate cycle begins again
81
Overall what happens in the malate-aspartate shuttle reactions?
NADH electrons are transported into the mitochondrial matrix used to reduce a mlc of NAD+, generates NADH the electrons are passed onto the electron transport chain

M104 T2 (15 decks)

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