2.2 Cell Respiration Flashcards
What is ‘Respiration’?
A series of enzyme-controlled reactions that releases energy from glucose to synthesise ATP molecules.
What is the word equation for respiration?
Glucose + Oxygen –> Carbon Dioxide + Water
What is the preferred respiratory substrate?
Glucose
What does ATP stand for?
Adenosine TriPhosphate
What are the two main roles of ATP?
- Act as energy transfer molecules
2. Carry out phosphorylation of molecules
What is ‘Phosphorylation’
Addition of an inorganic phosphate molecule
What is the role of coenzymes NAD in respiration?
Collect hydrogen ions and high energy electrons and deliver them to the electron transfer chain of aerobic respiration
What is the role of dehydrogenase enzymes?
1 - Remove hydrogen ions and high energy electrons during breakdown of glucose
2 - Pass them to coenzymes
What is the first stage of respiration?
Glycolysis
Where does Glycolysis occur?
Cytoplasm
What are the two stages known as in glycolysis?
Energy investment and Energy Payoff
What is meant by ‘Net gain of 2 ATP in Glycolysis’
- Invest 2 ATP
- Releases 4 ATP
Gain two more ATP than put in
What happens in animals after glycolysis in the absence of oxygen?
Pyruvate is converted into Lactic Acid
What is the end product of glycolysis?
Pyruvate
Is the conversion of pyruvate to lactic acid reversible or irreversible?
Reversible
What is pyruvate converted into in the absence of oxygen in yeast cells?
Ethanol and CO2
What is energy from the breakdown of ATP used for?
Muscle Contraction
Repair of Cells
Transport
What is the second stage of aerobic respiration?
Citric Acid Cycle
Where does the Citric Acid Cycle Occur?
Matrix of Mitochondria
What does the citric acid cycle result in?
- Generation of ATP
- Release of CO2
- Regeneration of Oxaloacetate
What happens to pyruvate before it becomes part of the cycle?
Converted into Acetyl Group, and then combines with coenzyme A to form Acetyl CoA
What is released in the conversion of pyruvate to Acetyl CoA?
CO2
NADH
What does Acetyl CoA combine with to form citric acid?
Oxaloacetate
At what two stages in the citric acid cycle is CO2 released?
During conversion of Pyruvate to Acetyl Group and during the conversion of Citric Acid to Oxaloacetate
What is the key product from stage 1 and 2 that is transported to stage 3?
NADH
What do dehydrogenase enzymes pass to coenzymes NAD?
High energy electrons
Hydrogen Ions
What is the final stage in aerobic respiration?
Electron Transport Chain
Where does the electron transport chain take place?
Inner membrane folds of the mitochondria (Cristae)
What is the final hydrogen/electron acceptor?
OXYGEN
Why do we need to breathe in every few seconds (in relation to respiration)?
In order to provide oxygen as the final hydrogen/electron acceptor
Describe the steps in the electron transport chain?
1 - Receives hydrogen and electrons from NADH
2 - Electrons are passed along the electron transport chain releasing energy.
3 - This energy is used to move H ions across the inner membrane.
4 - Flow of these H ions back across the membrane through ATP synthase results in ATP production
5 - Final hydrogen and electron acceptor is oxygen to create water.
Describe the role of NADH in the electron transport chain?
NADH provides hydrogen ions and high energy electrons. The high energy electrons are used to pump the hydrogen ions across the membrane.
