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By the end of this section, you will be able to:
  • Describe the process by which polymers are broken down into monomers
  • Describe the process by which monomers are combined into polymers
  • Discuss the role of ATP in metabolism
  • Explain oxidation-reduction reactions
  • Describe the hormones that regulate anabolic and catabolic reactions

Metabolic processes are constantly taking place in the body. Metabolism is the sum of all of the chemical reactions that are involved in catabolism and anabolism. The reactions governing the breakdown of food to obtain energy are called catabolic reactions. Conversely, anabolic reactions use the energy produced by catabolic reactions to synthesize larger molecules from smaller ones, such as when the body forms proteins by stringing together amino acids. Both sets of reactions are critical to maintaining life.

Because catabolic reactions produce energy and anabolic reactions use energy, ideally, energy usage would balance the energy produced. If the net energy change is positive (catabolic reactions release more energy than the anabolic reactions use), then the body stores the excess energy by building fat molecules for long-term storage. On the other hand, if the net energy change is negative (catabolic reactions release less energy than anabolic reactions use), the body uses stored energy to compensate for the deficiency of energy released by catabolism.

Catabolic reactions

Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in the chemical bonds. These energy releases (conversions) are not 100 percent efficient. The amount of energy released is less than the total amount contained in the molecule. Approximately 40 percent of energy yielded from catabolic reactions is directly transferred to the high-energy molecule adenosine triphosphate (ATP). ATP, the energy currency of cells, can be used immediately to power molecular machines that support cell, tissue, and organ function. This includes building new tissue and repairing damaged tissue. ATP can also be stored to fulfill future energy demands. The remaining 60 percent of the energy released from catabolic reactions is given off as heat, which tissues and body fluids absorb.

Structurally, ATP molecules consist of an adenine, a ribose, and three phosphate groups ( [link] ). The chemical bond between the second and third phosphate groups, termed a high-energy bond, represents the greatest source of energy in a cell. It is the first bond that catabolic enzymes break when cells require energy to do work. The products of this reaction are a molecule of adenosine diphosphate (ADP) and a lone phosphate group (P i ). ATP, ADP, and P i are constantly being cycled through reactions that build ATP and store energy, and reactions that break down ATP and release energy.

Structure of atp molecule

This diagram shows the chemical structure of adenosine triphosphate, and how different reactions add or remove phosphate groups.
Adenosine triphosphate (ATP) is the energy molecule of the cell. During catabolic reactions, ATP is created and energy is stored until needed during anabolic reactions.

Questions & Answers

What is a dorsal cavity?
John Reply
Explain in detail mitosis and meiosis
sedeck Reply
What is Sodium Potassium Pump?
Mwamba Reply
The process of moving sodium and potassium ions across the cell membrance is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+-ATPase
USAMA
yes men.
Carlos
does it mean that there are two definitions of gross anatomy
Esther Reply
what is anatomy?
Hridy Reply
I think it's the study of the internal and external features of the body and its physical relationship between body parts
Esther
anatomy is the study of all the structure of body parts of living organisms
Kishan
jaundice causes by when bilirubin blockage of bilary system
mahamed Reply
Yeah, when there is a blockage in the bilary system( bile ducts) which lead to obstruction of the bile pigments called bilirubin leading to a characteristically yellowish appearance of the eyes.
ibrahim
yes
mahamed
there are three main resons why bilirubin levels in the blood may rise: 1. pre-hepatic jaundice,2. hepatic jaundice, 3. post hepatic
mahamed
hi pls what causes jaundice
Umar Reply
where the love feelings emotions and hate lies in the body?
Loving Reply
what is Regional anatomy
Sharon Reply
Please information on dialysis
Agbo Reply
what is the relationship between Clinical officer general, unqualified professionals and traditional healers?
Purity Reply
is that how the microscopic anatomy is
Elizabeth Reply
to understand the structures of the body. to understand how the structures of the body work . To understand how the structures of the body work and support the functions of life.
Dora Reply
procedures that removes waste from body when kidneys dont function properly..
maribel Reply
Want to join
Ordeal
dialysis
kimunya
dialysis is a process to remove extra fluid , impurities and waste product from the blood and to correct electrolytes imbalance such as sodium, potassium and calcium with the help of dialysis machine. when the kidneys can't do their job.
Kishan
what will lead a person to dialysis
Agbo
what's metabolic acidosis
Nana
A condition in which too much acid accumulates in the body. Causes of metabolic acidosis can include buildup of body toxins, kidney failure, and ingestion of certain drugs or toxins, such as methanol or large doses of aspirin. It can be a rare complication of diabetes.
Loving
What is dialisis
Friday Reply
When kidney is not functioning properly than with the help of dialysis blood filtration is occur Or we can say that it is a process through which filtration of blood is done
sonugora
dialysis is a process of removing wastes, excess fluid ,impurities from the blood and to correct electrolytes imbalance such as sodium, potassium and calcium etc with the help of dialysis machine.when the kidney can't do their job.
Kishan

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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