Respiration Flashcards
(29 cards)
What are the 4 stages of aerobic respiration?
1) Glycolysis
2) Link reaction
3) Krebs cycle
4) Oxidative phosphorylation
Where does glycolysis occur?
In the cytoplasm
What are the 3 steps of glycolysis?
1) Phosphorylation of glucose - glucose phosphate using ATP
2) Production of TP
3) Oxidation of TP into pyruvate with gain of ATP + NADH
Describe phosphorylation of glucose
- 2 ATP are hydrolyzed to ADP and each releases a phosphate which attach at each end of the 6C glucose
- Glucose phosphate produced = very high energy
Describe production of TP
- Since glucose phosphate is very high energy and highly reactive it will split into 2 3C TP
Describe production of pyruvate
- Both TP will be oxidized
- The coenzyme NAD picks up a H from the TP = NAD is now reduced to NADH = TP oxidized
- This forms 2 pyruvate
- 2 ATP produced per pyruvate
Why is there a net gain of only 2 ATP when 4 are produced?
- Since we use 2 ATP at the start of glycolysis
- 4 are produced but overall the net gain will be 2 excluding the 2 ATP used
What are the products of glycolysis and what happens to them?
- 2 Pyruvate
- 2 NADH
- 2 net gain ATP
The pyruvate and NADH are actively transported to the mitochondrial matrix
Where does the link reaction take place?
In the mitochondrial matrix
Describe the link reaction
- Pyruvate is oxidized into a 2C acetate
- The H that is released during oxidation is picked up by coenzyme NAD - NADH
- 1C is released as CO2
- Acetate is then converted into 2C acetylcoenzyme A
- Acetate + Coenzyme A = Acetylcoenzyme A
What are the products of the link reaction for a glucose molecule?
- 2 Acetyl CoA
- 2 NADH
- 2 CO2
Where does the krebs cycle take place?
In the mitochondrial matrix
Describe the krebs cycle
- Acetyl CoA reacts with a 4C releasing CoA back to be recycled = 6C which enters cycle
- Decarboxylation to remove 2C as CO2
- Substrate level phosphorylation will form ATP from ADP + Pi
- A series of redox reactions that reduce 3 NAD and 1 FAD -> NADH + FADH
What are the products of the krebs cycle per cycle?
- 3 NADH
- 1 FADH
- 1 ATP
- 2 CO2
Where does oxidative phosphorylation take place?
In the mitochondrial cristae
Describe oxidative phosphorylation
- NADH + FADH carry the H to the cristae
- The H will split into H+ and e-
- e- move down the ETC through the embedded proteins in the cristae
- As it moves from protein-protein it releases energy
- The H+ is pumped across from matrix to intermembrane space using the energy
- Results in an electrochemical gradient in the IMS
- Go down the concentration gradient via ATP synthase via facilitated diffusion
- Diffusion causes the catalysis and phosphorylation of ADP + Pi = ATP
- Oxygen is the final electron acceptor in the chain
- The O2 in the matrix will pick up e- from the of ETC + H+ that have come back via ATP synthase = H2O
- 1/2(O2) + (2H+)+ 2e- → H2O
Why is aerobic respiration only 32% efficient?
- Proton leaks across mitochondrial membrane during oxidative phosphorylation
- ATP used to transport pyruvate and NADH to matrix
- Energy lost as heat
What is anaerobic respiration?
-Respiration in the absence of oxygen
- Takes place only in the cytoplasm
Describe anaerobic respiration for animals
- Incomplete breakdown of glucose
- Pyruvate is produced at the end of glycolysis and a net gain of 2 ATP
- Pyruvate is reduced by gaining a H+ from NADH which is oxidized to NAD
- Lactate is produced + H2O = Lactic acid which will denature enzymes = muscle fatigue = therefore anaerobic short term
- NAD can be reused in glycolysis and it can keep happening in absence of O2
What happens to the lactate produced in anaerobic respiration
- Transported to liver via bloodstream
- Converted into pyruvate
- Can enter the link reaction in liver cells
Describe anaerobic respiration for plants and microorganisms
- Incomplete breakdown of glucose
- Pyruvate is produced at the end of glycolysis and a net gain of 2 ATP
- Pyruvate is reduced by gaining a H+ from NADH which is oxidized to NAD
- Ethanol and CO2 is produced
- Ethanol = toxic = denature enzymes = only short term
- NAD can be reused in glycolysis and it can keep happening in absence of O2
Compare the efficiency between both respirations
AEROBIC:
- Total yield from 1 glucose molecule is 38 ATP
- More efficient
ANAEROBIC:
- Total yield from 1 glucose molecule is 2 ATP
- Less efficient
How do you investigate a variables effect on rate of respiration?
- Use a respirometer
- As the pressure changes in test tube as oxygen is taken in and CO2 is absorbed by NaOH
- Set a timer and see how far the colored liquid moves in a set period of time
- The volume decreases = pressure decreases
- Pressure is higher in the control tube = liquid moves towards experimental tube
How do you calculate rate of respiration?
Volume of O2 consumed or CO2 produced/ time * mass of sample
- Volume = π r2 * distance moved by colored liquid
