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All 12 Flashcards — ATP — the cell's energy currency
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Question
What does ATP stand for?
Answer
**Adenosine triphosphate** — a molecule with **three** phosphate groups.
Question
Why is ATP called the cell's 'energy currency'?
Answer
It is the **universal, spendable** form of energy — every energy-requiring process in the cell is paid for in ATP.
Question
Where in ATP is the usable energy stored?
Answer
In the **bond to the third phosphate group**.
Question
What is produced when ATP releases its energy?
Answer
**ADP + Pi** (adenosine diphosphate + an inorganic phosphate).
Question
Which conversion releases energy: ATP → ADP + Pi, or ADP + Pi → ATP?
Answer
**ATP → ADP + Pi** releases energy; **ADP + Pi → ATP** stores it.
Question
What supplies the energy to recharge ADP + Pi back into ATP?
Answer
**Cell respiration** — it releases energy from glucose to rebuild ATP.
Question
What is the ATP–ADP cycle?
Answer
The continuous interconversion: ATP is broken to **ADP + Pi** (releasing energy) and rebuilt from **ADP + Pi** by respiration (storing energy).
Question
Name two cell processes powered by converting ATP into ADP.
Answer
Any two of: **active transport, muscle contraction, synthesis of macromolecules, nerve-impulse transmission**.
Question
Give one feature of ATP that suits it to powering cell processes.
Answer
It releases a **small, usable** amount of energy in a **single step** (also: soluble; quickly recharged).
Question
How many phosphate groups do ATP and ADP have?
Answer
**ATP has three**; **ADP has two** (one phosphate is removed to release energy).
Question
Is ATP used up permanently, or reused?
Answer
**Reused** — each molecule is recharged by respiration and recycled thousands of times a day.
Question
Why is being soluble an advantage for ATP?
Answer
Being soluble lets ATP **move freely through the cytoplasm** to wherever in the cell energy is needed.
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Topic 3.2 hub
Cell respiration
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