Energy for the Cell

What is ATP?Universal energy currency - large amount of free energy

ATP - adenosine triphosphate

ATP is made up of: adenine, ribose, 3 phosphate groups

Energy stored in phosphate bonds

ATP Hydrolysis - ATP breaks down to produce ADP, a phosphate group, and a large amount of energy

ADP - adenosine diphosphate

ATP Synthesis - combining of ADP with P - requires energy

What is ATP?

How is ATP Formed?ATP can be synthesized in two ways:

Substrate Level Phosphorylation

Oxidative Phosphorylation

Substrate-Level Phosphorylation - formation of ATP by direct transfer of a phosphate group from a substance to ADP

Enzyme catalyzed

Oxidative Phosphorylation - formation of ATP using energy transferred indirectly from a series of redox reactions

Involves final electron acceptor (oxygen - electronegative)

Food as FuelMolecules with lots of C-H bonds are high in energy

Potential energy stored in food molecules is released during oxidation reactions

Oxidation - loss of electrons (removal of H, addition of O)

Reduction - gain of electrons (removal of O, addition of H)

Energy released is transferred to energy carrying molecules

Energy CarriersNAD+ - positively charged coenzyme

- called nicotinamide adenine dinucleotide

- high energy electron carrier (oxidized form)

NADH - reduced form of NAD+

- carries potential energy to drive ATP synthesis

What is Cellular Respiration?

Both plants and animals use aerobic cellular respiration to extract energy from food when oxygen is present

Aerobic Cellular Respiration - process that uses oxygen to harvest energy from organic compounds

C6H12O6 + 6O2 -> 6CO2 + 6H20 + energy

Oxidation of glucose occurs through a series of enzyme catalyzed reactions

Occurs in cytoplasm and mitochondria of cells

Mitochondria generate most of the ATP used in eukaryotes

What is Cellular Respiration?

Two ways to extract energy from food in absence of oxygen:

Anaerobic Respiration - uses an inorganic substance other than oxygen as the final oxidizing agent to produce ATP

Fermentation - uses an organic compound as the final oxidizing agent to produce ATP

2 types: Alcohol Fermentation and Lactate Fermentation

Alcohol FermentationAlcohol Fermentation - glucose from food is converted into carbon dioxide, ethanol (alcohol), and ATP (energy)

C6H12O6 -> 2CO2 + 2C2H6O + energy

Example: bread making, brewing beer, wine

Lactate FermentationLactate Fermentation - glucose from food is converted into lactate and ATP (energy)

C6H12O6 -> 2C3H5O3 + energy

Example: yogurt, some cheeses, strenuous exercise

To Summarize3 pathways produce ATP: aerobic respiration, anaerobic respiration, and fermentation

Respiration pathways use electron transport systems to generate ATP by oxidative phosphorylation

Fermentation pathways lack electron transport systems