As such, there are many different possible proteins — this varies depending on the number of sets of amino acids in a protein — each with its own particular function, ranging from attacking antigens in the blood, to regulating metabolism, to digesting particles of food.
Proteins are involved in most life processes. As macromolecules, nucleic acids serve as a detailed instruction manual for the development of the body and the workings of each cell. Nucleic acids form of the sugar 2-deoxyribose, a phosphate group, and one of four base molecules.
Different combinations of the four base molecules along the DNA chain encode for certain amino acids, which eventually connect together to form proteins. Found in many energy-providing foods, carbohydrates help the nervous system, muscles, and body in general function.
A group of polymers, they contain nothing but carbon, hydrogen, and oxygen. Human bodies break down carbohydrates into their base components, which it then uses to fuel cells and maintain body processes. Plants use carbohydrates, particularly cellulose, to protect their cells and to grow larger.
The list of carbohydrates is extensive and includes all sugars and starches. While carbohydrates supply immediate energy for the body, lipids — a class of macromolecule — provide long-term energy storage. A cell uses many chemical reactions in multiple enzymatic steps to slow the release of energy no explosion and more efficiently capture the energy held within the chemical bonds in glucose.
The first stage in the breakdown of glucose is called glycolysis , which occurs in an intricate series of ten enzymatic-reaction steps. The second stage of glucose breakdown occurs in the energy factory organelles, called mitochondria. One carbon atom and two oxygen atoms are removed, yielding more energy.
The energy from these carbon bonds is carried to another area of the mitochondria, making the cellular energy available in a form cells can use. Cellular respiration is the process by which energy is captured from glucose. If the body already has enough energy to support its functions, the excess glucose is stored as glycogen the majority of which is stored in the muscle and liver.
The amount of glycogen in the body at any one time is equivalent to about 4, kilocalories—3, in muscle tissue and 1, in the liver. Prolonged muscle use such as exercise for longer than a few hours can deplete the glycogen energy reserve. The weakening of muscles sets in because it takes longer to transform the chemical energy in fatty acids and proteins to usable energy than glucose. After prolonged exercise, glycogen is gone and muscles must rely more on lipids and proteins as an energy source.
Athletes can increase their glycogen reserve modestly by reducing training intensity and increasing their carbohydrate intake to between 60 and 70 percent of total calories three to five days prior to an event. People who are not hardcore training and choose to run a 5-kilometer race for fun do not need to consume a big plate of pasta prior to a race since without long-term intense training the adaptation of increased muscle glycogen will not happen.
The liver, like muscle, can store glucose energy as a glycogen, but in contrast to muscle tissue it will sacrifice its stored glucose energy to other tissues in the body when blood glucose is low.
Approximately one-quarter of total body glycogen content is in the liver which is equivalent to about a four-hour supply of glucose but this is highly dependent on activity level. The liver uses this glycogen reserve as a way to keep blood-glucose levels within a narrow range between meal times. Glucose is additionally utilized to make the molecule NADPH, which is important for protection against oxidative stress and is used in many other chemical reactions in the body.
If all of the energy, glycogen-storing capacity, and building needs of the body are met, excess glucose can be used to make fat. When food is consumed, the proteins are broken down into their constituent amino acids and rebuilt into the proteins of the body. However, excess amino acids are not stored for future use, and the body only starts to break down its own proteins during starvation, when the ordinary sources of fuel fats and carbohydrates are not available. An amino acid forming a peptide bond to a growing poly-peptide chain, releasing H 2 O.
Fats are the primary long-term energy storage molecules of the body. Fats are very compact and light weight, so they are an efficient way to store excess energy. A fat is made up of a glycerol, which is attached to 1 to 3 fatty acid chains. Most of the energy from fats comes from the many carbon bonds in these long, fatty acid chains.
Fatty acids connect to glycerol in the region where each molecule has an -O-H group. Two hydrogens and one oxygen are split off, forming H-O-H water and the long carbon chain is attached to the glycerol. Each glycerol can carry up to three fatty acid chains, which would make it a " tri-glyceride. To reverse the reaction and split the fatty acid from the glycerol, just add water and energy.
Glucose, a 6-carbon sugar, is a simple carbohydrate or " mono-saccharide. Larger, more "complex carbohydrates" are made by stringing together chains of glucose subunits into di-saccharides, tri-saccharides, poly-saccharides.
Starch is a complex carbohydrate which plants create for energy storage, and is the most common carbohydrate in the human diet. Foods like potatoes, corn, rice, and wheat are rich in starch. Animals break the starches back down into glucose subunits and convert the glucose into glycogen for storage. Glycogen is a complex storage molecule made from glucose using insulin.
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