Respiration Flashcards
Outline aerobic respiration
Requires oxygen and produces carbon dioxide, water and much ATP
Outline anaerobic respiration
Takes place in the absence of oxygen, and produces lactate (animals), or ethanol and CO2 (plants and fungi). Only a little ATP.
4 stages of respiration?
Glycolysis, link reaction, krebs cycle, oxidative phosphorylation
What does glycolysis produce?
Two 3C pyruvate molecules
Where does glycolysis occur?
Cytoplasm
Outline the process of glycolysis.
- Phosphoylation occurs (2 ATP hydrolysed into 2 ADP + Pi).
- Each molecule pf phosphorylated glucose is split into 2x 3C molecules (triose phosphate).
- This triose phosphate is oxidised, forming two molecules of pyruvate. The hydrogen (lost from oxidation) is transferred to NAD to form NADH.
- 4ATP are produced (net gain of 2).
What are the energy yields from glycolysis?
2 ATP
2NADH
2 pyruvate
How can glycolysis provide evidence for evolution?
Because it’s a universal feature of every organism
Why can glycolysis take place in the cytoplasm and not an organelle?
Because the enzymes for the glycolytic pathway are found in the cytoplasm.
Where does the link reaction occur?
Mitochondria
What is produced in the link reaction?
Acetyl CoA
How do the pyruvate molecules produced in glycolysis get from the cytoplasm to mitochondria?
Active transport
Outline the process of the link reaction
- The pyruvate molecules are actively transported to matrix of mitochondria.
- The pyruvate is oxidised into acetate. In this, the 3C pyruvate molecule loses a CO2 molecule and 2 hydrogens (which are used to form NADH).
3 The 2C acetate combines with CoA to produce acetyl CoA.
What is the word equation of the link reaction?
Pyruvate + NAD + CoA —> Acetyl CoA + NADH + CO2
The link reaction and krebs cycle occur twice for every glucose molecule. Why?
Because 2 pyruvate molecules are made for every glucose molecule entering glycolysis.
What is produced from the krebs cycle?
she ATP and a large quantity of NADH and FADH
Where does the krebs cycle occur?
Matrix of mitochondria.
What type of reactions occur in the krebs cycle?
A series of oxidation-reduction reactions.
Outline the process of the krebs cycle
- Acetyl CoA (from LR) combines with a 4C molecule to produce a 6C compound.
- In a series of oxidation-reduction reactions. the 6C compound loses 2 molecules of CO2 and hydrogen to give to a 4C molecule, and 1 ATP produced due to substrate level phosphorylation.
- The 4C molecule can now combine with a new molecule of acetyl CoA to begin the cycle again.
How many carbons does acetyl CoA have?
2C
For each molecule of pyruvate, the krebs cycle produces…
- 1 ATP
- 3x CO2
- reduced coenzymes e.g. NAD and FAD
How is the CO2 produced as a waste product in respiration removed?
During gaseous exchange
Where does oxidative phosphorylation occur?
Mitochondria (within the cristal (folded inner membrane), the enzymes and other proteins involved in OP are found)
What’s the difference between mitochondria in metabolically active cells?
- larger quantities
- more densely packed christie
Outline the process of oxidative phosphorylation
- NADH and FADH donate the hydrogen atoms they’re carrying to the first molecule in the electron transfer chain/
- The electrons pass along a chain of electron transfer molecules in a series of oxidation-reduction reactions .
As electrons flow down this chain, the energy they release causes the active transport of protons across the inner mitochondrial space into the inter-membranal space. - Protons accumulate in the inner membrane space. Then, they diffuse back into the matrix through ATP synthase channels imbedded in the inner-mitochondrial membrane.
- At the end of the chain, electrons and protons combine with oxygen to form water. (Oxygen is there terminal acceptor of electrons).
Why are the electrons carried by NAD and FAD not transferred in one explosive step in OP, but instead are passed along a series of electron transfer carrier molecules?
Because the transfer of electrons down an energy gradient allows their energy to be released gradually, therefore more usefully (e.g. not as heat).
Name two alternative respiratory substrates
Lipids and proteins
Outline the respiration of protein as an alternative respiratory substrate
It is first hydrolysed into its constituent AAs. These have their amino group removed (deamination) before entering the respiratory pathway at different point depending on the amount of carbon they contain.
Outline the respiration of lipids as an alternative respiratory substrate
Lipids are first hydrolysed into glycerol and fatty acids.
The glycerol is then phosphorylated and converted into triode phosphate which enters the glycolysis pathway and subsequently the Krebs cycle.
The fatty acid component is broken down into 2C fragments which are converted to acetyl CoA (then enters Krebs cycle)
How many times does decarboxylation happen during one turn of the Krebs cycle?
Twice
What do electrons lose as they move along the electron transport chain in oxidative phosphorylation?
Energy
What is the total amount of ATP that can be produced from one glucose molecule?
32
