Respiration Flashcards
Describe how oxidation takes place in glycolysis and in the Krebs cycle.
• removal of hydrogen/dehydrogenation;
• by enzymes/dehydrogenases;
• H accepted by NAD/reduced NAD formed;
• in Krebs cycle, FAD (used as well);
Water is a waste product of aerobic respiration. Describe how water is formed at the end of aerobic respiration.
• oxygen is terminal/final electron acceptor;
• combines with electrons and protons (to form water);
Explain how the amount of ATP is increased by reactions occurring inside a mitochondrion
• oxidation of/removal of electrons and H+
• from pyruvate
• acetyl CoA / 6 carbon compound; (credit oxidative decarboxylation)
• substrate level production of ATP / ATP produced in Krebs cycle;
• production of reduced NAD / FAD (allow they take up hydrogen);
• in matrix of mitochondria;
• electrons fed into electron transport chain / used in oxidative
• (Electrons) pass along carriers/through electron transport chain/through series of redox reactions;
• Energy released;
• Protons move into intermembrane space;
• ADP/ADP + Pi;
• ATP synthase;
Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP.
OR
Describe the events of oxidative phosphorylation
• NAD/FAD reduced / hydrogen attached to NAD/FAD;
• H+ ions/electrons transferred from coenzyme to coenzyme/carrier to carrier (ETC on cristae of inner membrane)
• Energy released (from electrons) through series of redox reactions;
• Energy released used to pump H+/ protons into intermembrane space;
• H+/ protons flow back through ATP synthase to produce ATP from ADP and phosphate.
The mitochondria in muscles contain many cristae. Explain the advantage of this.
• larger surface area for electron carrier system / oxidative phosphorylation;
• provide ATP / energy for contraction;
Give two reasons why the respirometer was left for 10 minutes when it was first placed in the water bath.
• Equilibrium reached;
• Allow for expansion/pressure change in apparatus;
• Allow respiration rate of seeds to stabilise;
Explain why a log scale is used to record the number of cells/bacteria.
• Large range/difference/increase in numbers;
• Accept reference to exponential (increase)
Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration.
• Regenerates NAD / Oxidises reduced NAD;
• (So) glycolysis continues;
Why is glucose not used directly as a source of energy
Takes time to break the bonds compared to ATP which requires only 1 step to break down
Explain the advantage of a mitochondria containing many Cristae
- larger surface area for electron carrier system
-oxidative phosphorylation
-provides more ATP for muscle contraction
What are the 4 stages in aerobic respiration
- glycolysis (cytoplasm)
- link reaction (matrix)
- kerbs cycle (matrix)
- Electron transport chain (mitochondrial membranes)
What is substrate level phosphorylation
ATP generated directly through energy released via respiration reactions. This occurs in glycolysis and the Krebs cycle.
What is oxidative phosphorylation
ATP generated from the chemical energy released when a reduced hydrogen carrier or coenzyme (NADH2) OR (FADH2) has been oxidised at the electron transfer chain.
Glycolysis involves the conversion of…
….glucose to pyruvate
Glycolysis of glucose yields
- 2 NET ATP directly by substrate level phosphorylation
- 2 reduced NAD which will also be used to produce ATP by oxidative phosphorylation
-2 molecules of pyruvate
The steps to glycolysis
- Glucose is a stable molecule
- glucose is phosphorylated by the hydrolysis of 2 ATP to 2 ADP to provide 2 phosphates
- to produce phosphorylated glucose which is unstable
- phosphorylated glucose spilts into 2 x triose phosphate
- triose phosphate is then oxidised to pyruvate
- this step involves the loss of H from dehydrogenase enzyme which reduces the hydrogen carrier molecules NAD to NADH2 (reduced NAD)
- 2 x ATP is produced directly at this stage via substrate level phosphorylation
Each link reaction produces…
- (2) reduced NAD (which will be used to produce ATP by oxidative phosphorlyalation)
- (2) acetyl co A
- (2)CO2
- As 2 molecules of pyruvate are produced from one molecule of glucose there will be 2 molecules of acetyl co A produced
After pyruvate is produced in glycolysis where does it go
It is actively transported into the matrix
Steps of the link reaction
- Pyruvate is oxidised to acetate
- The hydrogen removed is used to reduce the NAD
- A molecule of CO2 is lost (decarboxylation)
- Coenzyme A binds to the acetate
- to produce acetyl coenzyme A
Equation for the link reaction
Pyruvate (3c) + NAD + coA ——> acetyl coA (2C) + NADH2 + CO2
What is the Krebs cycle
A series of enzyme controlled redox reactions that take place in the MATRIX of the mitochondria
Steps to the Krebs cycle
- acetyl co A combines with 4c molecule to form 6c compound
- 6c compound loses CO2 and hydrogen
- NAD is reduced
- Forms 5c compound
- converts to 4c compound loses CO2 and produces 1x ATP via substrate level phosphorylation, 2x reduced NAD, 1x reduced FAD
- cycle continues
X2 PER GLUCOSE
The Krebs cycle produces…
- 2 x CO2 produced
- some ATP produced directly by substrate level phosphorylation
-3 x reduced NAD and 1 reduced FAD to be used in oxidative phosphorylation
Describe how oxidation takes place in glycolysis and in the Krebs cycle
- Removal of hydrogen/dehydrogenation
2.by enzymes/dehydrogenase - H accepted by NAD to form reduced NAD
- Reduced FAD is also produced in the Krebs cycles
Water is a waste product of aerobic respiration. Describe how water is formed at the end of aerobic respiration
- Oxygen is the final electron acceptor
- Combines with electrons and protons to form water
Steps of the electron transport chain or oxidative phosphorylation
- The reduced H carriers (reduced NAD and FAD) are oxidised losing hydrogen.
- The electrons from the hydrogen pass down a series of electron carriers in a series of redox reactions
- Electrons lose energy which is used to pump protons into the inter membrane space
- Some energy lost as heat
- H+ diffuse down a proton gradient into the matrix via ATP synthase
- Energy from this forms ATP
- Electrons and H+ recombine with oxygen gas to form water
- Oxygen is the final electron acceptor
Without oxygen at the ETC what would happen
Without oxygen removing the H+ protons and electrons, there would be a back up of electrons along the ETC and the process of cellular respiration in the mitochondria will stop
What is the net gain of ATP in aerobic respiration
38 per glucose molecule
What is the net gain of ATP in anaerobic respiration
2 ATP per glucose molecule
What is the equation to calculate the rate of respiration in a respirometer
Rate = volume
————
Time x mass
