ATP and Energy

Forms of Energy To understand the cell completely we have to define how it gets energy and how it uses that energy Energy is the capacity to cause change or do work

Forms of Energy Kinetic energy is the energy of motion Moving objects can perform work by transferring motion to other matter Heat is a type of kinetic energy that is transferred among randomly moving atoms Light is another type of kinetic energy

Forms of Energy Potential energy is energy that matter posses as a result of its location or structure This is stored energy that can be released at any time Chemical energy is the potential energy available for release in a chemical reaction

Thermodynamics Thermodynamics is the study of energy transformations that occur in a collection of matter In thermodynamics everything that is being studied is called the system Everything else in the universe is the surroundings

Thermodynamics There are three laws of thermodynamics – We only care about two of them The first law of thermodynamics states energy in the universe is constant This means that energy can be transferred and transformed but not destroyed This means that a power plant does not create energy, it converts it from one form to another

Demo

Thermodynamics The second law of thermodynamics states that conversions of energy create entropy of the universe Entropy is the random disorder or randomness in the universe

DEMO

Exergonic and Endogenic Exergonic reactions are reactions that release energy Exergonic literally means energy outward Endergonic reactions are reactions that yield products rich in potential energy Endergonic means energy inward

ATP ATP (adenosine triphosphate) is a molecule that is vitally important to a cell It powers nearly every cellular function The name tells us how it is built

ATP Because of how it is structured it is often compared to a loaded spring All three phosphate groups are negatively charged, so they repel each other

ATP As a result the bonds can be broken by hydrolysis The hydrolysis of ATP is exergonic The energy that is released can be used to power other parts of the cell

ATP The phosphate group that leaves can be transferred to another molecule When this happens we transfer energy from an exergonic reaction to an endergonic reaction This is called phosphorylation

ATP Work There are three main types of work that ATP does – Chemical – Mechanical – Transport

ATP Work In chemical work the phosphorylation of reactants provides energy to drive the endergonic synthesis of products That’s a lot of fancy words that basically mean it helps create a potentially strong molecule

ATP Work In mechanical work the transfer of phosphate groups into motor proteins allows cells to change protein shape This physically moves cells and allows them to change shape and pull or push

ATP Work In transport work transport proteins use ATP to drive the cell membrane pumps that pump molecules across a concentration gradient This phosphorylation of transport proteins allows cells to move molecules across their membranes