Energy is usually liberated from the ATP molecule to do work in the cell.
Energy is usually liberated from the ATP molecule to do work in the cell by a reaction that removes one of the phosphate-oxygen groups, leaving adenosine diphosphate (ADP). When the ATP converts to ADP, the ATP is said to be spent.  (First law of Thermodynamics states that energy in the universe is constant). Rather, cells make ATP in order to convert energy (such as the chemical energy stored in food) into a useful form that can be used to drive cellular work. ATP is the common energy currency of cells. Hydrolysis of its high energy phosphate bonds releases energy that can be used to perform cellular work, such as driving chemical reactions and transporting substances across membranes.  Jack Tormoehlen Cells use ATP for energy. The energy comes from releasing a phosphate group from ATP to create ADP. This energy is used throughout the Cell for various functions. ATP contains a purine base, adenine, a sugar, ribose, and three phosphate groups. The adenine and ribose combine to make adenosine. ATP is produced in many ways. Fermentation, respiration and photosynthesis are the main ways. Cells use ADP (Adenosine di-phosphate) and add a phosphate group. After ATP is broken down into ADP and a phosphate group, the parts recycle to form ATP again. The ongoing process of breaking and rejoining phosphate groups is what keeps the cell going There are several different ways that Cells can make ATP from ADP and inorganic phosphate (Pi). One of the more common ways is when the phosphate group is transferred to ADP f … rom a molecule that is more energetic than ATP. This form of biosynthesis is called substrate-level phosphorylation. It is one of two such reactions in glycolysis and is the main reason why the degradation of glucose can be used to produce useful energy. For example, when glucose is taken up from the blood stream by muscle cells and degraded to produce ATP that can be used in muscle contraction. ALL cellular work-all the activities of life-requires energy, either from ATP or from related molecules. A lot of oxygen is required for this process! The sugar AND the oxygen are delivered to your cells via your bloodstream. This process occurs partially in the cytoplasm, and partially in the mitochondria.  ATP transports chemical energy within cells for metabolism. It is one of the end products of photophosphorylation, cellular respiration, and fermentation and used by enzymes and structural proteins in many cellular processes, including biosynthetic reactions, motility, and cell division.  Confidence votes 20. When ATP drives work in cells, phosphate groups don't just fly off into space. ATP energizes other molecules in cells by transferring phosphate groups to those molecules. This helps cells perform three main kinds of work: mechanical work, transport work, and chemical work. It is one of two such reactions in glycolysis and is the main reason why the degradation of glucose can be used to produce useful energy. For example, when glucose is taken up from the blood stream by muscle cells and degraded to produce ATP that can be used in muscle contraction. When ATP drives work in cells, phosphate groups don't just fly off into space. ATP energizes other molecules in cells by transferring phosphate groups to those molecules. It is one of two such reactions in glycolysis and is the main reason why the degradation of glucose can be used to produce useful energy. For example, when glucose is taken up from the blood stream by muscle cells and degraded to produce ATP that can be used in muscle contraction. Just like we need energy to get through the day, individual cells need energy for survival too. Cellular respiration is the process by which cells get their energy in the form of ATP. There are two types of cellular respiration, aerobic and anaerobic. Aerobic respiration is more efficient and can be utilized in the presence of oxygen, while anaerobic respiration does not require oxygen. 
http://creationresearch.org/crsq/articles/36/36_1/atp.html https://answers.yahoo.com/question/index?qid=20100506185323AAeERTd https://prezi.com/goosjmtlkysh/why-do-cells-use-atp/ http://www.answers.com/Q/Why_does_the_cell_need_ATP http://www.biology.iupui.edu/biocourses/N100/2k4ch7respirationnotes.html https://en.wikipedia.org/wiki/Adenosine_triphosphate http://www.answers.com/Q/Why_does_the_cell_need_ATP http://www.answers.com/Q/Why_does_the_cell_need_ATP https://www.wyzant.com/resources/lessons/science/biology/cellular-respiration
why do cells need atp