The live-cell is a small chemical factory, with thousands of processes taking place inside a minuscule area. When needed, sugars can be transformed into amino acids, which are then linked together to form proteins.

Proteins, on the other hand, are broken down into amino acids that can be converted to glucose during digestion. Many cells in multicellular creatures release chemical compounds that are utilized in other areas of the organism.

This cellular economy is powered by the process of cellular respiration, which extracts the energy stored in sugars and other fuels. Cells use this energy to do a variety of tasks, such as transporting solutes across the plasma membrane.

The energy held in specific chemical compounds is converted to light by these dinoflagellates, a process known as bioluminescence. The majority of bioluminescent creatures live in the waters, although some may be found on land, such as the bioluminescent firefly seen in the little photo.

A cell's bioluminescence and other metabolic processes are carefully coordinated and regulated. As a chemical factory, the cell is unparalleled in its complexity, efficiency, and reactivity to small changes. This chapter's metabolic ideas will help you comprehend how matter and energy move during life's activities and how that flow is controlled.

Energy is the ability to effect change. Energy is essential in everyday life because various types of energy may be utilized to accomplish work—that is, to move matter against opposing forces like gravity and friction.

• The term Energy, in other words, is the power to reorganize a group of matter. You expend energy, for example, turning the pages of this book, and your cells expend energy in moving some chemicals across membranes. Energy occurs in different forms, and the capacity of cells to convert energy from one form to another is essential to life.

• The term kinetic energy refers to the energy that can be associated with the relative motion of objects. Moving objects can perform work by imparting motion to other matter

Pool players utilize the motion of the cue stick to push the cue ball, which in turn moves the other balls; water flowing through a dam powers turbines; and leg muscles contract to push bicycle pedals.

The term Thermal energy is the kinetic energy associated with the random movement of atoms or molecules; heat is thermal energy transferred from one item to another.

Light is a sort of energy that may be used to power labor, such as photosynthesis in green plants.

An item that is not currently moving may nonetheless have energy. Potential energy is nonkinetic energy; it is energy that matter contains due to its position or structure.

We may imagine a cell's metabolism as a detailed road map of the hundreds of chemical processes that occur within it, organized into intersecting metabolic pathways.

A metabolic route starts with a certain molecule that is subsequently changed in a series of specified steps to produce a specific product.

Each stage of the route is catalyzed by a different enzyme: there are mechanisms that regulate these enzymes, balancing metabolic supply and demand, similar to how red, yellow, and green stoplights control the flow of car traffic.

Metabolism as a whole controls the cell's material and energy resources. Some metabolic processes provide energy by decomposing complex molecules into simpler ones.

Catabolic routes, or breakdown pathways, are the names given to these degradative processes. Cellular respiration is a key route of catabolism in which sugar glucose and other organic fuels are broken down to carbon dioxide and water in the presence of oxygen. (Pathways may begin with more than one molecule and/or product.)

Energy stored in organic molecules becomes accessible for cell activity such as ciliary beating or membrane transfer.

Anabolic routes, on the other hand, use energy to construct complex molecules from smaller ones; they are also known as biosynthetic pathways.

The energy of the cosmos is constant, according to the fundamental rule of thermodynamics: energy may be moved and changed, but it cannot be generated or destroyed.

The first law is often known as the concept of energy conservation. The electric company does not create energy; rather, it converts it into a form that we can utilize. A plant functions as an energy transformer, not an energy generator, by converting sunlight to chemical energy.

If energy cannot be destroyed, why can't organisms just recycle their energy? It turns out that with every energy transfer or transformation, some energy becomes unavailable for use in doing labor. Most energy transformations convert the more useful types of energy to thermal energy, which is then emitted as heat.

Only a tiny portion of the chemical energy from the meal is converted into the motion of the brown bear shown; the majority is lost as heat, which dissipates fast through the environment.

Living cells unavoidably convert different sources of energy to heat while carrying out chemical processes that do various types of labor.

As a result of the loss of useable energy as heat to the environment, each energy transfer or transformation causes the cosmos to become more chaotic. We are all familiar with the term "disorder" in the context of a cluttered space or a dilapidated structure. However, the term "disorder" as used by scientists has a particular chemical definition relating to how distributed energy is in a system and how many distinct energy levels are present.

For the sake of simplicity, we will refer to molecular disturbance as “disorder” in the following discussion because our common concept (the dirty room) provides a fair parallel for the molecular disorder.