Cellular Respiration Part I: Introduction to Energy Harvesting

It sound simple but…… Why do you have to eat? – What does it have to do with entropy? Why do you have to breathe? Can you give an AP Biology level answer to these questions? 2

What do you know about this molecule?

ATP The cell’s energy currency Energy is released when a phosphate is removed from the molecule. Respiration fuels the addition of P to ADP Unstable, short-term energy storage

High Energy Phosphate Bonds 5 Ribose -

Light energy ECOSYSTEM Photosynthesis in chloroplasts Cellular respiration in mitochondria CO 2  H 2 O  O 2 Organic molecules ATP powers most cellular work ATP Heat energy

Sequence These From Greatest To Least Chemical Energy

Greatest to Least

The Principle of Redox Chemical reactions that transfer electrons between reactants are called oxidation- reduction reactions, or redox reactions In oxidation, a substance loses electrons, or is oxidized (its oxidation number increases) In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)

Example 11 Energy Products Reactants becomes reduced becomes oxidized Methane (reducing agent) Oxygen (oxidizing agent) Carbon dioxideWater

Oxidation of Organic Fuel Molecules During Cellular Respiration During cellular respiration, the fuel (such as glucose) is oxidized, and O 2 is reduced becomes oxidized becomes reduced

Cellular respiration includes both aerobic and anaerobic respiration but is often refers to aerobic respiration Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with the sugar glucose C 6 H 12 O O 2  6 CO H 2 O + Energy (ATP + heat energy) Respiration

Big Energy Events of Respiration – Glycolysis (breaks down glucose into two molecules of pyruvate) – The citric acid cycle (completes the breakdown of glucose) – Oxidative phosphorylation (accounts for most of the ATP synthesis)

So…..Why do we have to eat? Answer the question using your AP Biology level understanding of energy transfer. Be ready to share your answer. 16