TCA cycle and Oxidative Phosphorylation Flashcards
What does TCA cycle stand for and what is it?
Tricarboxylic acid cycle aka Krebs cycle and is the final pathway where oxidative metabolism of AA, carbs, and fatty acids converge
AEROBIC PATHWAY
Where does the Citric acid cycle occur?
The cycle occurs in mitochondria close to the electron transport chain (ETC)
What happens to reduced co-enzymes produced by glycolysis, lipid metabolism, and TCA cycle?
The reduced co enzymes such as NADH are oxidised
The cycle is not viewed as a closed circle but instead as a?
A traffic circle with compounds entering and leaving as required (many intermediates too)
What can catabolism of some AAs lead to?
Can generate intermediates of the cycle important to glucose formation from AAs
Where are TCA cycle enzymes located?
TCA cycle enzymes are located in a free or attached state to the inner mitochondrial membrane close to respiratory enzymes
Following glycolysis, pyruvate moves into the mitochondria however it is catalysed into Acetyl CoA? How and what helps it become this?
Pyruvate dehydrogenase aids the oxidative decarboxylation reaction that turns pyruvate +CoA into acetyl CoA + CO2
This reaction produces 2 ATP and 2NADH
What co enzymes help pyruvate dehydrogenase form acetyl CoA?
NAD,FAD,CoA, thiamine
Explain step one of the citric acid cycle
Acetyl CoA (C2) joins with oxaloacetate (C4) via citrate synthase (no energy required) to form CITRATE (C6)
Explain step two of the citric acid cycle involving citrate
Citrate is isomerised and hydroxyl group moved via h20 moving in and out to form isocitrate (C6)
Enzyme involved is aconitase
What is the step in the citric acid cycle involving isocitrate?
Isocitrate dehydrogenase produces NADH and CO2 by removing a carboxyl and hydrogen from the isocitrate, forming Alpha-ketoglutarate (C5)
Explain the step in the citric acid cycle involving alpha ketoglutarate
a-ketoglutarate dehydrogenase produces NADH and CO2 and succinyl CoA (C4)
(Same as isocitrate step basically)
Explain the step of the citric acid cycle involving succinyl CoA?
Succinate thiokinase forms succinate (C4) and byproduct of GTP
Explain the step involving succinate
Succinate (C4) oxidised into numerate (C4) and byproduct of FADH2 is formed
Explain the step involving fumarate
Fumarate catalysed by fumarase to form malate no byproducts
Explain last step of citric acid cycle involving malate
Malate dehydrogenase forms oxaloacetate and byproduct of NADH
Circle of life the two extra carbons that enter the cycle leave as CO2
How many NADH, FADH2, and direct ATP are formed?
3 NADH= 3 ATP each = 9 ATP
1 FADH2 = 2 ATP each = 2 ATP
1 direct ATP
Total ATP of citric acid cycle = 12 ATP
How many runs does the citric acid cycle do from one glucose molecule and where do the byproducts go such as NADH,CO2?
Two runs for each glucose (pyruvate is C3 and two are formed)
Byproducts go to ETP electron transport chain
Transamination of amino acids what does it lead to in citric acid cycle?
Leads to formation of TCA cycle intermediates
What happens to the FADH2 and NADH generated in glycolysis and citric acid cycle?
These reduced coenzymes can enter the electron transport chain where each coenzyme donates a pair of electrons to specialised electron carriers
Where are the electron carriers and coenzymes and what are they called?
They are embedded within the inner membrane
Complex I
CoQ
Complex III
Cytochrome C
Complex IV
Complex V (ATP Synthase)
What is the process of oxidative phosphorylation (ETP)
As electrons are passed down energy is lost from them and placed into the production of ATP
What do the electrons do specifically to lead to ATP production
Electrons from NADH FADH2 pass through complexes generating a proton motive force which is used to produce ATP via ATP synthase
How many ATP are produced from the oxidation of a single glucose molecule? (remember glucose gives two pyruvate)
40-2= 38 ATP in total
