Respiration Flashcards
What are the 4 stages of respiration?
Glycolysis
Link Reaction
Krebs Cycle
Oxidative Phosphorylation
Describe glycolysis
Stages are investment, cleavage and energy harvest
Takes place in the cytoplasm
Stage 1 -investment
- Glucose is an unreactive molecule so must be phosphorylates to become reactive
- Phosphate molecule comes from the conversion of ATP to ADP
Stage 2 - cleavage
- 6C phosphorylated glucose is split into 2 3C sugars called triose phosphate
Stage 3 - energy harvest
-2 pairs of hydrogen atoms are removed and donated to NAD
- This is oxidation
- NAD+ = electron carrier
- 2 x 3C molecules of pyruvate are formed resulting in the formation of 2 ATP
Describe the Link reaction
Happens in the matrix of the mitochondria
- Pyruvate is decarboxylated and is also being oxidised.
- This is because NAD+ is reduced by the gain of hydrogen to form NADH.
- This then makes a 2C compound called acetate.
- CoA ( co enzyme A) is then added to form acetyl CoA, a 2 carbon compound
Describe the Krebs Cycle
Happens in the matrix of the mitochondria
- Acetyl CoA react with oxoaloacetate, a 4C compound, and the CoA is removed to form a 6C compound called citrate.
- Citrate is then decarboxylated and oxidised through the reduction of NAD+ to NADH.
- This forms alpha ketoglutarate, a 5C compound.
- This is then decarboxylated further as well as being oxidised by the reduction of NAD+
- It is then further oxidised by FAD2+ being reduced to FADH.
- ADP + Pi forms ATP again
- This all forms oxoaloacetate again, a 4C compound.
Can happen 2 times as glycolysis due to 2 x pyruvate
Describe oxidative phosphorylation
Happens in the membrane across the cristae
- NADH is oxidised and loses H+ and electrons.
-H+ then gains energy from the excited electrons and move into the space between membranes and electrons are in the electron transport chai. - Electrons also come from oxidised FADH2
- There will be a high concentration of H+ in the membrane space which means they need to use facilitated diffusion
- This cause an electrochemical gradient and ATP synthase is used to aid diffusion
- This causes ADP + Pi –> ATP
-2H+ and 2e- combine to form hydrogen and react with oxygen to form water - Oxygen is the terminal acceptor
Aerobic respiration makes 32 ATP
How many are made in each stage?
Glycolysis = 2 ATP
Krebs = 2 ATP
Oxidative phosphorylation = 28 ATP
Give examples of when anaerobic respiration will occur
When there is a lack of oxygen
- intense exercise
- underwater
- water logged soils
Only the ______ stage of aerobic respiration occurs with anaerobic respiration
Net gain of ___ ATP
first
2
Give the equation for anaerobic respiration in animals
pyruvate + NADH –> Lactic acid + NAD+
the NADH donates H to pyruvate
NAD+ can then be recycled
Give the equation for anaerobic respiration in plants
pyruvate + NADH –> ethanol + carbon dioxide + NAD+
NADH donates H to pyruvate and the NAD+ can be recycled to be used again in glycolysis
The energy produced in anaerobic respiration is ___ ATP compared to the energy produced in aerobic respiration is ____ ATP
2
32
Why is it important that lactic acid is converted back to pyruvate?
It is important that lactic acid is converted back to pyruvate when oxygen is available so that aerobic respiration can restart at the link reaction and produce significantly more ATP.
Lipids in respiration?
Lipids are first hydrolysed into glycerol and fatty acids
Glycerol is phosphorylated into 2 triose phosphate
TP enters glycolysis
Fatty acids are broken down into 2C compounds and are converted into acetyl CoA
They enter at the Krebs Cycle
Breaking down lipids releases lots of H+ which feed into the electron transport chain producing more energy than when glucose is used
Proteins in respiration?
Protein is first hydrolysed into amino acids
These have their amino group removed (deaminated) before entering the respiratory pathways at different points
3C compounds are converted into pyruvate and enter link reaction
4-5C compounds are converted into intermediated in the Krebs cycle
Look at folder / GC / book for practicals
