8.2 Cell respiration (HL) Flashcards
5 steps of respiration `
- Glycolysis
- Link reaction
- Krebs cycle
- Electron transport chain
- Chemiosmosis
Mitochondria: Function of outer membrane
Contains transport proteins that enable movement of pyruvate from cytosol
Mitochondria: Function of inner membrane/cristae and how its adapted for efficiency
Contains ETC and ATP synthase. Inner membrane is folded which increases SA:V ratio for more available surface
Mitochondria: Function of matrix
Central cavity that contains all the enzymes and suitable pH for Krebs cycle and link reaction
Mitochondria: Function of DNA and ribosomes
Ribosomes synthesize proteins/enzymes for aerobic respiration while naked DNA maintains function
Mitochondria: Inter-membrane space function and how its adapted for efficiency
Used to create hydrogen ion gradient upon proton accumulation. It has a small space between membrane to maximize gradient
What is electron tomography?
A technique for obtaining 3D structures of sub-cellular structures using electron micrographs
Electron carrier
A molecule that is capable of accepting electrons from one molecule and donating it to another in process of electron transport
What are the two most common electron carriers in cell respiration? Give oxidized and reduced form
- NAD+–> NADH + H+
- FAD+ –> FADH2
FAD and NAD are reduced
When does oxidative phosphorylation take place?
During ETC and chemiosmosis
Phosphorylation and its effect
Addition of phosphate groups, making molecule less stable and reaction occurs faster
Glycolysis: Why are lipids and proteins not preferred compared to carbs?
Lipids are harder to transport and digest but will yield more energy. Proteins can release dangerous nitrogenous compounds
Glycolysis: Where does it occur?
In the cytosol
Glycolysis: Summary of process
- Hexose is broken down into molecules of pyruvate (3C) + one phosphate group through hydrolysis
- Two hydrogen carriers are reduced
- Net total of 2 ATP molecules are produced
Glycolysis: Where does energy go when glucose molecule is broken down?
Most of the potential energy is retained in the two pyruvates
Glycolysis: Where is there net total of 2 ATP?
Phosphate group from pyruvate is added back to initial 2 ADP however other inorganic phosphate groups are also present so they get added to ADP due to energy release. 4 ATP produced but 2 were used up in the beginning
Glycolysis: What is direct synthesis of ATP called?
Substrate level phosphorylation
Glycolysis: What happens to hydrogen in pyruvate molecule?
It reduces NAD+ to NADH. NADH will go through ETC to produce more ATP
Glycolysis: How does this process relate to anaerobic respiration?
As glycolysis is the only process that doesn’t require oxygen, only 2 ATP is produced. Pyruvate will be converted to lactic acid or ethanol+CO2
Link reaction: What process takes place?
Oxidative decarboxylation
Link reaction: Summary of process
- Pyruvate enters matrix
- Enzymes uses O2 to remove one carbon and make CO2 and also remove one hydrogen
- NAD+–> NADH
- CoenzymeA has acetyl group (2C)and becomes acetyl CoA which enters Krebs cycle
Link reaction: How many times does reaction occur?
2 pyruvates means link reaction occurs twice per molecule of glucose
Link reaction: What does the acetyl group consist of?
2 remaining carbons
Krebs cycle: Where does it occur?
Matrix
Krebs cycle: Summary of process
- Pyruvate + acetyl CoA enter
- 2C + 4C sugar form hexose
- Oxidative decarboxylation of 6C=>5C + CO2
- Again 5C=> 4C + CO2
- Between 6-5C and 5-4C, NAD and FAD are reduced and provide electrons for ETC
Krebs cycle: What happens to acetyl CoA after decarboxylation?
It becomes CoA which returns to link reaction and is recycled
Krebs cycle: How many NADH and FADH2 are produced?
3 NADH and 1 FADH2 per cycle
Krebs cycle: How much ATP is produced?
1 ATP per cycle
Krebs cycle: How much CO2 is produced?
2 per cycle between each decarboxylation
Krebs cycle: How many times does it occur?
Occurs twice as there are two molecules of acetyl CoA
How many decarboxylation reactions are there in aerobic respiration?
- 1 in link reaction and 2 in Krebs cycle
What is the max yield of one glucose?
38 ATP
ETC: Why does it happen?
Electrons have to be removed as energy to synthesize ATP is derived from oxidation of H carriers
ETC: Where does it happen?
Inner mitochondrial membrane
ETC: What is the process called?
Oxidative phosphorylation part I
ETC: Summary of process
- Oxidization of carriers lead to release of high energy electrons and photons
- Energy is used to pump H+ ions in the matrix across inner membrane and electrons lose energy
- H+ ions accumulate in inter-membrane space creating conc. gradient
- Ions then return to the matrix through ATP synthase down EC gradient
Chemiosmosis: What is it?
Diffusion of protons across semi-permeable membrane, through ATP synthase
Chemiosmosis: What is the process involved called?
Oxidative phosphorylation part II
Chemiosmosis: Summary of process
- Proton motive force will cause H+ ions to move down gradient and diffuse into matrix
- Once through ATP synthase, the H+ ions trigger molecular rotation of enzyme, synthesizing ATP
Chemiosmosis: Why does reduction of oxygen take place?
- De-energized electrons must be removed for ETC to continue
Chemiosmosis: Summary of oxygen reduction
- Oxygen is final electron acceptor for ETC and combination prevents chain from being blocked
- O2 also binds with free protons to form water in matrix which removed excess ions and maintains gradient
Chemiosmosis: What happens in absence of oxygen?
Hydrogen carriers cannot transfer energized electrons to ETC and ATP production is stopped
During aerobic respiration, which sequence do electrons follow?
Glucose>NADH>ETC>Oxygen
In cellular respiration, the energy for most ATP synthesis is supplied by?
A proton gradient across a membrane
