Energy Carriers in Respiration (Leaving Cert Biology): Revision Notes

Energy Carriers in Respiration

Respiration involves energy carriers that store and transport energy during the process. The two main carriers are ATP and NADH.

1. ATP (Adenosine Triphosphate)

What is ATP?

• ATP is the primary energy carrier in cells.
• It stores energy in its chemical bonds and releases it when needed.

Structure of ATP:

• ATP is made of:
  1. Adenine (a nitrogen base).
  2. Ribose (a sugar molecule).
  3. Three phosphate groups.

How ATP Works:

1. When the bond between the last two phosphate groups is broken, energy is released.

• Reaction: ATP → ADP + P + Energy

2. ATP is then rebuilt using energy from respiration:

• Reaction: ADP + P + Energy → ATP

2. NADH (Nicotinamide Adenine Dinucleotide)

What is NADH?

• NADH is a high-energy electron carrier.
• It transports electrons and hydrogen ions (H⁺) during respiration.

How NADH is Formed:

• During respiration, NAD⁺ (low-energy form) picks up: 4. Two high-energy electrons (2e⁻). 5. One hydrogen ion (H⁺).
• This forms NADH, a high-energy molecule.
  • Reaction: NAD⁺ + 2e⁻ + H⁺ → NADH

Role of NADH in Respiration:

When NADH breaks down, it releases high energy electrons and a hydrogen ion.

NADH → NAD⁺ + 2e⁻ + H⁺