Gr 11 ATP Structure

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Why do we eat food?

To get Energy!

Our cells transform food energy into useable energy in the form of ATP

What is APT?

The chemical substance that serves as the currency of energy in a cell is adenosine triphosphate (ATP). ATP is referred to as currency because it can be “spent” in order to make chemical reactions occur. The more energy required for a chemical reaction, the more ATP molecules must be spent.

ATP Structure

atp.pdf

Presentation on ATP Structure and Functions in the human body

ATP (adenosine triphosphate) is a high energy molecule that functions as an immediate source of power for cell processes

One molecule of ATP contains three covalently linked phosphate groups – which store potential energy in their bonds
When ATP is hydrolysed (to form ADP + Pi) the energy stored in the phophate bond is released to be used by the cell
Cell respiration uses energy stored in organic molecules to regenerate ATP from ADP + Pi (via oxidation)

Biological Chemistry

Redox Reactions

When organic molecules are broken down by cell respiration, the chemical energy is transferred by means of redox reactions

Redox reactions involved the reduction of one chemical species and the oxidation of another (redox = reduction / oxidation)

Most redox reactions typically involve the transfer of electrons, hydrogen or oxygen

Reduction is the gain of electrons / hydrogen or the loss of oxygen
Oxidation is the loss of electrons / hydrogen or the gain of oxygen

Energy released by oxidation reactions is carried to the cristae of the mitochondria by reduced NAD and FAD

Cell respiration breaks down organic molecules and transfers hydrogen atoms and electrons to carrier molecules

As the organic molecule is losing hydrogen atoms and electrons, this is an oxidation reaction
Energy stored in the organic molecule is transferred with the protons and electrons to the carrier molecules

The carrier molecules are called hydrogen carriers or electron carriers, as they gain electrons and protons (H⁺ ions)

The most common hydrogen carrier is NAD⁺ which is reduced to form NADH (NAD⁺ + 2H⁺ + 2e^– → NADH + H⁺)
A less common hydrogen carrier is FAD which is reduced to form FADH₂ (FAD + 2H⁺ + 2e^– → FADH₂)

The hydrogen carriers function like taxis, transporting the electrons (and hydrogen ions) to the cristae of the mitochondria

The cristae is the site of the electron transport chain, which uses the energy transferred by the carriers to synthesize ATP
This process requires oxygen to function, and hence only aerobic respiration can generate ATP from hydrogen carriers
This is why aerobic respiration unlocks more of the energy stored in the organic molecules and produces more ATP

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