2.3 energy and atp Flashcards
Q: Why do organisms need energy?
A: For biological processes such as active transport, muscle contraction, DNA replication, cell division, and protein synthesis.
Q: What is the immediate source of energy for cellular processes?
A: ATP (adenosine triphosphate).
Q: Why is ATP known as the “energy currency” of the cell?
A: It transfers energy from energy-yielding processes (e.g., respiration) to energy-requiring processes.
Q: What is the structure of ATP?
A: ATP is composed of adenine (a nitrogenous base), ribose (a pentose sugar), and three phosphate groups.
Q: What type of bonds are found between the phosphate groups in ATP?
A: High-energy bonds (phosphoanhydride bonds).
Q: What happens when ATP is hydrolyzed?
A: ATP is broken down into ADP (adenosine diphosphate) and an inorganic phosphate (Pi), releasing energy.
Q: What enzyme catalyzes the hydrolysis of ATP?
A: ATP hydrolase (also called ATPase).
Q: Write the equation for ATP hydrolysis.
A: ATP + H₂O → ADP + Pi (+ energy).
Q: How is the energy released during ATP hydrolysis used?
A: It is coupled to energy-requiring reactions (e.g., active transport or muscle contraction)
Q: Why is ATP a good energy carrier?
A: It releases energy in small, manageable amounts, is rapidly hydrolyzed, and can be regenerated.
Q: How is ATP synthesized?
A: By the condensation of ADP and Pi using energy from respiration.
Q: What enzyme catalyzes the synthesis of ATP?
A: ATP synthase.
Q: Write the equation for ATP synthesis.
A: ADP + Pi → ATP (+ H₂O).
Q: What are the three ways ATP can be synthesized?
A:
1. Photophosphorylation: In chloroplasts during photosynthesis.
2. Oxidative phosphorylation: In mitochondria during aerobic respiration.
3. Substrate-level phosphorylation: When phosphate groups are directly transferred from a molecule to ADP.
ATP in Cells
Q: Why is ATP not stored in large amounts?
A: ATP is unstable and is constantly regenerated from ADP and Pi as needed.
