carbohydrate metabolism Flashcards
(24 cards)
glycolysis converts 1 molecule of glucose into two molecules of what
pyruvate
what is carbon monoxide an inhibitor of and what impact does it have
cytochrome c in the mitochondrial electron transport chain
it prevents oxygen from binding, effectively halting the electron transport chain and cellular respiration
cytochrome c function
transferring electrons to oxygen, which is the final electron acceptor in the chain.
what is the chemiosmotic mechanism
the primary mechanism for ATP synthesis in mitochondria
It involves the electron transport chain (ETC), which generates a proton gradient across the inner mitochondrial membrane. The energy from this gradient is used by ATP synthase to produce ATP. This process is called oxidative phosphorylation.
what is substrate level phosphorylation
occurs during glycolysis and the citric acid cycle.
In this case, ATP is directly synthesized from high-energy substrates like phosphoenolpyruvate or GTP (which can be converted to ATP) without the involvement of the electron transport chain or a proton gradient.
The pentavalent form of arsenic (AsO43-) inhibits which enzyme?
glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the glycolytic pathway.
When arsenate is present, it forms arsenate ester instead of the normal phosphate ester. This results in the loss of energy (ATP production) because arsenate cannot be further metabolized in the glycolysis pathway in the same way phosphate can.
Which is the correct order for the stages involved in the full biological oxidation of glucose in cells with mitochondria, under aerobic conditions?
1.Glycolysis (cytoplasm) – Converts glucose to pyruvate, generating ATP and NADH.
2.Pyruvate Transport into Mitochondria – Via pyruvate shuttles (malate-aspartate or glycerol-3-phosphate shuttle).
3.Pyruvate Decarboxylation (Pyruvate Dehydrogenase Complex) – Converts pyruvate to acetyl-CoA, producing NADH and CO₂.
4.Citric Acid Cycle (Krebs Cycle) – Acetyl-CoA is oxidized to produce NADH, FADH₂, ATP (or GTP), and CO₂.
5.Electron Transport Chain (ETC) – NADH and FADH₂ donate electrons to the chain, creating a proton gradient.
6.Oxidative Phosphorylation (Chemiosmosis) – ATP synthase uses the proton gradient to produce ATP; oxygen accepts electrons to form water.
what are the substrates of the first reaction in glycolysis
glucose and ATP
catalysed by hexokinase (or glucokinase in liver)
the overall equation of Glycolysis is:
Glucose+2NAD++2ADP+2Pi→2Pyruvate+2NADH+2ATP+2H2O
Glucose (6 carbons) is metabolized through a series of enzyme-catalyzed reactions.
2 NAD⁺ molecules are reduced to 2 NADH, capturing high-energy electrons.
2 ADP and 2 inorganic phosphate (Pᵢ) are used to generate 2 ATP molecules through substrate-level phosphorylation.
2 Pyruvate molecules (3 carbons each) are produced as the end product.
2 molecules of water (H₂O) are released as byproducts during the process.
what does the chemosmotic mechanism involve
The storage of energy in the form of a proton gradient, which is then used to drive the phosphorylation of ADP to ATP by the ATP-synthase complex
How much ATP is produced through oxidative phosphorylation?
Approximately 2.5 ATP for each NADH reduced and 1.5 ATP for each FADH2 reduced
whats the overall equation of the citric acid cycle in animal cells
Acetyl-CoA + 2H2O + 3NAD+ + FAD + GDP + Pi –> 2CO2 + 3NADH + FADH2 + CoA-SH + GTP
Which subunit of ATP synthase contains the catalytic centre responsible for synthesizing ATP?
The F1 subunit of the ATP synthase contains the catalytic centre that synthesises ATP
What happens to the NADH and FADH2 resulted from the oxidation of glucose, fatty acids and amino acids in cells, in order to produce more ATP under aerobic conditions?
They are oxidized to NAD⁺ and FAD by transferring electrons to components of the mitochondrial electron transport chain.
fructose can also be metabolised by glycolysis. This is achieved in muscle cells by its conversion to:
Fructose 6-phosphate
Glycolysis is the pathway that fully oxidises glucose to carbon dioxide and water. true or false
false
The final step in Gluconeogenesis is catalysed by which enzyme and where does it occur
glucose-6-phosphatase.
The final step involves the conversion of glucose-6-phosphate to glucose. This step occurs in the endoplasmic reticulum of the liver and kidneys.
The enzyme glucose-6-phosphatase catalyses the hydrolysis of glucose-6-phosphate, releasing free glucose into the bloodstream.
what is a competitive inhibitor of succinate dehydrogenase
malonate
Malonate is a competitive inhibitor of succinate dehydrogenase because it closely resembles succinate and competes for the enzyme’s active site, preventing succinate from binding and being converted to fumarate. However, malonate cannot undergo the reaction, effectively inhibiting the enzyme.
what is most likely to be caused by an uncoupler of oxidative phophorylation
Operation of the electron transport chain without ATP production
An uncoupler of oxidative phosphorylation is a substance that disrupts the coupling between the electron transport chain (ETC) and ATP production.
dissipating the proton gradient as heat rather than using it to produce ATP.
Which compounds store the majority of the chemical energy from glucose by the end of glycolysis, pyruvate dehydrogenase reaction and the citric acid cycle?
NADH and FADH₂
These NADH and FADH₂ will then proceed to the electron transport chain (ETC), where they will donate their electrons to generate ATP through oxidative phosphorylation.
what is not true about the pyruvate produced through glycolysis
Pyruvate is decarboxylated to acetaldehyde, which is then reduced to ethanol and NADH is reoxidised to NAD+
what is the best representation of the overall reaction of the biological oxidation of glucose through cellular respiration is
glucose + 6 oxygen = 6 carbon dioxide + 6 water + energy
What happens to the carbon atoms from sugars, fatty acids and amino acids that undergo biological oxidation in the process of cell respiration?
they get fully oxidized and released as carbon dioxide
Glycogen phosphorylase exists as two isoforms (a and b). What is an allosteric activator of the a isoform, but not the b isoform?
AMP
