Respiration Flashcards
How does the structure of the mitochondria relate to its function
- ## Large surface area due to cristae which enables the membrane to hold many electron transport proteins and ATP synthase channels
Overall equation for respiration
C6H1206 + 6 O2 → 6 CO2 + 6 H20
What are autotrophs
organisms that are able to synthesise their own usable carbon compounds from carbon dioxide in the atmosphere through photosynthesis
Describe the process of glycolysis
- Phosphorylation of glucose using ATP
- Oxidation of triose phosphate to pyruvate
- Net gain of ATP
- NAD reduced
What is the overall yield from glycolysis
- 2 molecules of ATP
- 2 molecules of reduced NAD
- 2 molecules of pyruvate
Where does the link reaction take place
matrix of the mitochondria
Describe the stages of the link reaction
- pyruvate is oxidised to to acetate. - Hydrogens are accepted by NAD to reduce NAD
- acetate combines with co-enzyme A to form acetyl co-enzyme A
- each pyruvate molecule produces a CO2 molecule
-link reaction occurs twice for every glucose molecule
What is the overall equation for the link reaction
pyruvate+ Co enzyme A+ NAD —-> acetyl co enzyme A + reduced NAD + CO2
Describe the Krebs cycle
- Acetyl co A reacts with a 4-carbon molecule, releasing co-enzyme A and producing a 6-carbon molecule that enters the Krebs cycle
- In a series of redox reactions the Krebs cycle generates reduced co enzymes and ATP by substrate level phosphorylation
What does the Krebs cycle and link reaction produce for each molecule of pyruvate
- reduced co enzymes
- 3 molecules of Co2
- one ATP
What is the significance of the Krebs cycle
- Breaks down macromolecules into smaller ones- pyruvate broken down into CO2
- produces hydrogen atoms that are carried by NAD in the form of NADH to the electron transfer chain and provide energy for oxidative phosphorylation.This leads to the production of ATP which provides energy for the cell
- regenerates the 4 carbon molecule that combines with acetyl co enzyme A which would otherwise accumulate
The electron transfer chain in oxidative phosphorylation
- The hydrogen atoms produced in glycolysis and the Krebs cycle combine with co-enzymes NAD and FAD
- The reduced NAD and FAD donate the electrons from the hydrogen atoms to the first molecule in the electron transfer chain
- The electrons pass along a series of electron carrier transfer molecules in a series of oxidation-reduction reactions. As the electrons flow along the chain they release energy which causes the active transport of protons across the inner mitochondrial membrane and into the inter-membranal space
- Protons accumulate in inter-membranal space and then diffuse into the matrix through ATP synthase channels which causes ATP to be produced
- At the end of the chain electrons combine with these protons and oxygen to form water. Oxygen is the final electron acceptor
Where does oxidative phosphorylation take place
The mitochondrial membrane
What is the benefit of the energy being released in stages in the electron transfer chain
- when energy is released a little at a time more of it can be harvested
- for this reason the electrons are passed along a series of electron transfer carrier molecules down an energy gradient
-this allows the energy to be released gradually and more usefully
Respiration of lipids
- Lipids hydrolysed to glycerol and fatty acids
- Glycerol is phosphorylated and converted to triose phosphate which enters glycolysis and then krebs
- Fatty acid component is broken down into 2- carbon fragments which are converted to acetyl co-A. This then enters Krebs
- The oxidation of lipids produces 2-carbon fragments of carbohydrate and many hydrogen atoms (used to produce ATP during oxidative phosphorylation. For this reason lipids release more than double the amount of energy for the same mass of carbohydrate
Respiration of protein
- Hydrolysed to amino acids
- These have their amino groups removed before entering the respiratory pathway at different point depending on the number of c atoms they contain
- 3-c compounds are converted to pyruvate while 4 and 5 carbon compounds are converted to intermediates in the Krebs cycle
why can’t the Krebs cycle or electron transfer chain continue when oxygen isn’t present
- No FAD or NAD available to accept protons produced in krebs
- enzymes stop working
How is NAD regenerated in yeast cells
-pyruvate loses a molecule of CO2 and accepts a hydrogen atom from NADH to produce ethanol
How is NAD regenerated in animal cells
- each pyruvate molecule takes up two hydrogen atoms from the reduced NAD to form lactate
Why does converting pyruvate to lactate allow for the continued production of ATP
- Regenrates NAD
- NAD used in glycolysis
what is the advantage of converting lactate back to pyruvate when the muscles are well supplied with oxygen
- pyruvate is used in aerobic respiration
- lactic acid is toxic and causes cramp
Why does respiration produce more molecules of ATP per molecule of glucose in the presence of oxygen then without
- Oxygen is the final electron acceptor
- Oxidative phosphorylation provides most ATP
- Only glycolysis occurs without oxygen not the other stages
What happens to reduced NAD when the cell is respiring anaerobically
- converted back to NAD
- passes H to pyruvate
