Cellular Respiration Flashcards
What is cellular respiration?
Step-by-step breakdown of high-energy glucose molecules to release energy
Takes place day and night in all living cells and occurs in stages controlled by enzymes.
What are the four metabolic stages of cellular respiration?
- Glycolysis
- Pyruvate oxidation
- Krebs cycle
- Electron transport chain
Where does glycolysis occur?
In the cytosol
What is the equation for cellular respiration?
C6H12O6 + 6O2 → ATP + 6H2O + 6CO2 (+ heat)
What is ATP in the context of cellular respiration?
Energy currency of cells
How often does a working muscle cell recycle its ATP molecules?
About once each minute
What is anaerobic respiration?
Respiration without O2, occurs in the cytosol
What is aerobic respiration?
Respiration using O2, occurs in mitochondria
What is the net gain of ATP from glycolysis?
2 ATP
What are the products of glycolysis?
- 2 ATP
- 2 NADH
- 2 pyruvate
What is the primary role of glycolysis in cellular respiration?
To break down glucose into pyruvate
What happens to pyruvate in the presence of oxygen?
It is converted to acetyl CoA and enters the Krebs cycle
What is the Krebs cycle also known as?
Citric Acid Cycle
Where does the Krebs cycle occur?
In the mitochondrial matrix
What is the primary function of the electron transport chain?
To produce ATP through oxidative phosphorylation
What is substrate-level phosphorylation?
ATP is formed when an enzyme transfers a phosphate group from a substrate to ADP
What is the fate of NADH during fermentation?
It is recycled to NAD+
What are the two types of fermentation?
- Alcoholic fermentation
- Lactic acid fermentation
What is produced during alcoholic fermentation?
- Ethanol
- CO2
What is produced during lactic acid fermentation?
Lactic acid
What is the role of ATP synthase in cellular respiration?
To allow H+ to flow through and bond Pi to ADP to form ATP
What is the significance of electron carriers like NADH and FADH2?
They transfer electrons to the electron transport chain
How many NADH are produced in one turn of the Krebs cycle?
3 NADH
Fill in the blank: Glycolysis is an _______ pathway.
[ancient]
True or False: Glycolysis occurs only in aerobic conditions.
False
What is the evolutionary significance of glycolysis?
It is utilized by all cells and evolved in an anaerobic atmosphere
What is the purpose of the grooming phase in cellular respiration?
To prepare pyruvate for entry into the Krebs cycle
How many ATP are generated from one molecule of glucose in glycolysis?
4 ATP produced, net gain of 2 ATP
What happens to pyruvate under anaerobic conditions?
It undergoes fermentation
What is the initial reactant for glycolysis?
Glucose
What is the net gain of ATP from the Krebs cycle?
2 ATP
The Krebs cycle also yields 8 NADH and 2 FADH2.
What are the primary roles of NADH and FADH2 in cellular respiration?
Electron carriers and H carriers
They are reduced molecules that move electrons and H+ ions to be used in the Electron Transport Chain.
How much ATP can be yielded from one glucose molecule in the Electron Transport Chain?
~34 ATP
This occurs only in the presence of O2 (aerobic respiration).
What is the function of the Electron Transport Chain?
Transport of electrons linked to pumping of H+ to create H+ gradient.
What is chemiosmosis?
The diffusion of ions across a membrane
It links the Electron Transport Chain to ATP synthesis.
Who proposed the chemiosmotic hypothesis?
Peter Mitchell
This revolutionary idea was proposed in 1961 and further developed in 1978.
What happens to electrons as they flow through the Electron Transport Chain?
They move downhill to O2, releasing energy in a controlled manner.
What is the final electron acceptor in the Electron Transport Chain?
O2
What occurs if O2 is unavailable during cellular respiration?
ETC backs up, ATP production ceases, and cells run out of energy.
What is the role of ATP synthase in cellular respiration?
Synthesizes ATP from ADP and Pi using the H+ gradient.
List the main products of glycolysis.
- 2 ATP
- 2 NADH
- 2 pyruvate
What are the products of the Krebs cycle per glucose molecule?
- 2 ATP
- 6 NADH
- 2 FADH2
- 4 CO2
Fill in the blank: The process by which glucose is broken down to pyruvate is called _______.
Glycolysis
What are the two main types of energy carriers produced during cellular respiration?
- NADH
- FADH2
True or False: The Krebs cycle directly produces the majority of ATP in cellular respiration.
False
The majority of ATP is produced during the Electron Transport Chain.
What is the significance of the proton motive force in ATP synthesis?
It drives the flow of protons through ATP synthase to generate ATP.
What happens to the protons (H+) during the Electron Transport Chain?
They are pumped across the inner mitochondrial membrane to create a gradient.
How do fats enter the Krebs cycle?
They are degraded into individual fatty acids and glycerol, which are then converted to acetyl-CoA.
What is the process called when excess intermediates from the Krebs cycle are used to build necessary molecules?
Biosynthesis
Fill in the blank: The main purpose of the Krebs cycle is to _______ energy carriers.
produce
What is the role of oxygen in cellular respiration?
It acts as the final electron acceptor in the Electron Transport Chain.
What does the term ‘oxidative phosphorylation’ refer to?
The process of ATP production linked to the transfer of electrons to O2.
What are the consequences of a lack of ATP in cells?
Cells run out of energy and can die.
List the energy tokens produced during cellular respiration.
- 2 ATP from Glycolysis
- 2 ATP from Krebs Cycle
- ~34 ATP from Electron Transport Chain
