Oxidative Phosphorylation Flashcards
What happens to the hydrogen atoms from the Krebs cycle?
The are carried by the coenzymes NAD and FAD into oxydative phosphorylation
What are available in the cristae?
Proteins, lipids, traces of DNA and the enzymes and proteins needed for oxidative phosphorylation
What is the site of oxidative phosphorylation?
The cristae
Where do the mitochondria occur most frequently?
In metabolically active cells such as the liver, muscles and epithelial cells. Which all carry out active transport
What is different about the mitochondria in metabolically active cells?
The cristae are more densely packed, allowing for a greater surface area of membrane incorporating enzymes and other proteins involved in oxidative phosphorylation
How is the ETC formed?
The electrons from the Krebs cycle are transferred down a series of electron carriers which together form the ETC
What happens to the reduced NAD and FAD?
They donate the electrons of the hydrogen atoms they are carrying to the first molecule in the ETC
What happens to the electrons as they pass along the ETC?
They pass along the ETC in a series of oxidation-reduction reactions
What is released as electrons pass down the ETC?
Energy
What does the energy released from the ETC cause?
The active transport of protons across the inner mitochondrial membrane and into the inter-membrane space
What happens to the protons in the inter-membranal space?
They accumulate, before they diffuse back into the mitochondrial matrix through ATP synthase channels embedded in the inner mitochondrial membrane
What happens to the electrons at the end of the chain?
They combine with the protons that just diffuse through the ATP synthase channels and oxygen to form water
What is the final electron acceptor in the ETC?
Oxygen
What is the theory that describes the ETC?
Chemiosmotic theory
What would happen if oxygen wasn’t there to accept the hydrogen atoms?
The hydrogen ions and electrons would ‘back up’ along the chain and respiration would come to a halt
Why are electrons passed down a chain and not passed at once
The greater the energy that is released in a single step, the more of it is released as heat and then less is available for useful purposes
What is significant amount electron carrier molecules in the ETC?
Each carrier is at a slightly lower energy level therefore the electrons move down a gradient allowing their energy to be released gradually
What are the alternative respiratory substrates?
Lipids and proteins
How are lipids respired?
- they are first hydrolysed to glycerol and fatty acids
- the glycerol is then phosphorylated to triose phosphate which can enter the glycolysis pathway and then the Krebs cycle
- the fatty acid is broken down into 2-carbon fragments which are converted to acetyl coenzyme A
What does the oxidation of lipids produce?
2-carbon fragments of carbohydrate and hydrogen atoms which are used to produce ATP in oxidative phosphorylation
Compared to carbohydrates, how much energy is released from respiring a lipid molecule?
More than double
How are proteins respired?
- they are first hydrolysed to amino acids
- amino acids have their amino group removed in the process of destination before entering the Krebs cycle depending on the number of carbons they contain
When respiring proteins, what happens to the different carbon length molecules?
- 3-carbon molecules are converted to pyruvate
- 4- and 5-carbon compounds are converted to intermediates in the Krebs cycle
Why is the term oxidative phosphorylation used to describe the ETC?
The movement of electrons along the ETC is due to oxidation and the energy from the electrons combines with inorganic phosphate and ADP to form ATP in phosphorylation
State one advantage of the folding of the cristae on the ETC
It provides a large surface area of membranes which incorporate the coenzymes NAD and FAD and electron carriers that transfer electrons along the chain
Explain the role of oxygen in aerobic respiration
Oxygen is the final acceptor of the electrons and hydrogen ions in the ETC, without it, electrons would accumulate along the chain and respiration would cease
As part of what molecule does oxygen leave as after being respired?
Water molecule
