The term macromolecule refers to a polymer or a large molecule formed by weak covalent bonds. A polymer is made up of repeating units. A molecule is a grouping of two or more atoms that are chemically bonded together.
These large molecules are formed by linking together many smaller molecules, and they must have at least two repeating units. The smaller molecules are called monomers. Polymers are classified by the type of bond: Ionic and covalent.
- Ionic polymer – An ionic polymer is a polymer that sis formed from anionic and cationic monomers (ions, atoms with a positive or negative charge). The polymerization of these monomers creates a negative ion (cation) and a positive ion (anion).
- Covalent polymer – A covalent polymer is a large molecule formed by linking two or more small molecules called monomers.
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There are four types of biological macromolecules, namely:
- Nucleic acids
- Lipids and fats
Proteins are biological macromolecules made of amino acids which function in numerous ways. Their roles include catalyzing specific reactions and binding to receptors. They also transport molecules from one location to the next while providing shape/structure.
Proteins are classified based on their:
- Structure: fibrous or globular.
Fibrous proteins are large, rope-like macromolecules. Examples of fibrous proteins are collagen and keratin.
Globular proteins are small and spherical. Examples of globular proteins are hemoglobin and myoglobin.
- Function: enzymes, hormones, intercellular proteins, and antibodies.
Enzymes are catalysts for specific reactions in the body. Examples of enzymes are lipase and amylase.
Hormones are signaling molecules. Examples of hormones are growth hormones, insulin, and cortisol.
Intercellular proteins link cells together in tissues and organs. Examples of intercellular proteins are integrin and laminin.
Some proteins also make up the Extracellular Matrix function.
Antibodies are responsible for the immune response. Examples of antibodies are IgG and IgE.
Carbohydrates are biological macromolecules made of carbon, hydrogen, and oxygen and have the general formula Cn(H2O)n. The building blocks of carbohydrates are called saccharides.
These large molecules produce energy that fuels the physiological functions of the body. The energy generated by carbohydrates is used for:
- Regulation of body temperature and respiration.
Carbohydrates are classified into three main types, namely:
- Monosaccharides. These are simple sugars containing one sugar unit and general formula Cn(H2O)n. The main monosaccharides are glucose, galactose, and fructose.
Some substances that contain monosaccharides are Fruits, vegetables, and cane sugar. Glucose is the body’s primary energy source, while galactose and fructose are essential components of milk.
- Disaccharides. They are a combination of two simple sugars. The main disaccharides are lactose, maltose, and sucrose. Examples of substances containing disaccharides are milk and table sugar.
- Polysaccharides. The building blocks of these molecules are three or more monosaccharides. Examples of polysaccharides are starch and cellulose.
These polymers are used for various body functions. Starch is used as a storage form of glucose in plants, and it is found in potatoes. It’s usually broken down into simple sugars to emit energy.
Cellulose is a polysaccharide that composes plant cell walls, and it’s indigestible to humans. Cellulose is found in plant leaves and cotton (fibers).
Chitin and cellulose are polysaccharides that give strength to plant cells and are also used by insects in their exoskeletons.
3. Nucleic Acids
Nucleic acids are biological macromolecules that contain a sugar molecule and nucleic acid bases. They carry the genetic information in all living organisms.
The primary nucleic acids are:
- Deoxyribonucleic acid (DNA)
- Ribonucleic acid(RNA).
DNA is the central storage of genetic information, and it is found in the chromosomes of a cell. A single cell has a nucleus containing a double-stranded molecule of DNA.
RNA is involved in protein synthesis, regulation of gene expression, and other roles in living organisms. It also acts as a messenger for DNA, and it’s the main component of ribosomes.
Nucleotides are the building blocks of nucleic acids. They are classified into two groups based on their structure:
Purines are made of two rings and have the general formula C5H4N4O2. They consist of bases adenine and guanine.
“Adenosine Triphosphate (ATP)” is an example of a molecule containing the purine base adenine.
ATP is the primary energy source of living organisms, and it’s found in all cells of the body.
Pyrimidines are made of a single ring and have the general formula C3H4N2O. They are nitrogenous bases with rings composed of carbon and nitrogen. Examples of pyrimidines are cytosine, thymine, and uracil.
“Cytidine Triphosphate (CTP)” is an example of a molecule containing the pyrimidine base cytosine. It’s involved in the synthesis of DNA and RNA molecules.
4. Lipids and Fats
Lipids and fats are biological macromolecules that are insoluble in water. They are the main components of living organisms, and they can be classified as:
These biological macromolecules are used to store energy in plants and animals. They can be found in the cell membrane, which acts as an insulator and can transport organic substances.
Tissues in the body contain mostly water, and the amount of fats and lipids varies from one tissue to another.
Fatty acids are essential parts of triglycerides, phospholipids, and cholesterol. They have the general formula CnH2n+1COOH, and they are composed of 1 to 24 carbon atoms.
These refer to materials made by humans. In biological systems, the term macromolecule refers to large molecules that are not needed in small concentrations.
Synthetic macromolecules are made from inorganic or organic compounds. They are used in various applications, including construction and medicine.
The process of making synthetic polymers is called polymerization. The main groups of synthetic polymers are plastics, and they include:
- Polyethene. It is used in plastic bags, ropes, and pipes.
- Polystyrene. It is used in plastic cups, food containers, and plates. Polyvinyl Chloride (PVC), used in pipes and plastic films.
Plastics are also referred to as organic polymers since they contain carbon-hydrogen bonds. They’re usually made from petroleum products.
Polymers are also classified based on their size:
- Large or macromolecular polymers (macromonomers). They’re commercially available and are used in the construction industry. Examples are starch, cellulose, wood, and cotton.
- Small or synthetic polymers (polydisponsers) are used for water treatment, laundry detergents, and paints.
Plastics are also used as food additives. They’re commonly known by the acronym BPA, which stands for bisphenol-A. Some of these plastics have been identified as harmful to human health, and they’ve replaced BPA in particular food containers.
An example of these polymers is the cellulose found in plants used to make paper, clothes, and cellophane. They are made from living organisms through a process called Biosynthesis.
Biosynthesis involves the use of enzymes and coenzymes to catalyze a reaction. It’s done inside the cell in the cytoplasm. Below are some biosynthetic processes:
- Photosynthesis. In this process, plants use sunlight to convert carbon dioxide into glucose.
- Chemosynthesis. Here, bacteria make glucose using chemicals instead of sunlight.
- ATP synthesis
Two main reaction processes happen between monomers and polymers in living systems:
Condensation is the reaction process between two smaller molecules to form a big one without losing atoms or other groups. This reaction happens in biological macromolecules such as nucleic acids and proteins.
During dehydration reaction, water is removed from the smaller compounds. The smaller units join together to form larger molecules. Protein synthesis is an example of dehydration synthesis. Amino acids join together to create protein chains.
The body uses this process to make polymers. When you digest food and absorb its molecules, they’re used to synthesize macromolecules such as proteins, nucleic acids, and fats.
In dehydration synthesis, water is released, and new bonds are formed between the two reactants. The original compounds can be used to make other biological molecules.
Our guide on the fluid mosaic model may also aid in visualizing the cells as well as providing more understanding of these macromolecules.
Hydrolysis is the chemical reaction in which a molecule is cleaved by water. Hydrolysis can happen to polymers as well as monomers. This process can be reversible, where the monomers are separated, and water is added back to them.
During hydrolysis, the bonds connecting the monomers or polymers are broken, and smaller molecules are formed, such as water and smaller sugars.
Hydrolysis helps in the metabolism of macromolecules in the body. For instance, proteins are broken down into amino acids, which can then be recycled to make new proteins.
This process benefits the body by ensuring that:
- The proteins are not used up for a long time.
- Some of the amino acids can be reused to form new proteins without getting rid of them completely.
- During digestion, the body absorbs amino acids and uses them as food.
- Some of the proteins can be hydrolyzed into individual sugars, such as glucose.
Polymers also undergo hydrolysis in living systems; they’re used in DNA replication and cell division.
The macromolecules undergo hydrolysis until they’re of small enough size for the body to absorb them.
Proteins, for example, are hydrolyzed in the stomach and broken down into amino acids by digestive enzymes. They’re then absorbed into the bloodstream and used for growth and repair by different cells.
The hydrolysis of macromolecules takes place in a specific sequence depending on the type of bond joining them.
Our guide on food macromolecules can provide more information!
Macromolecules are complex, and there is a lot that you can learn about them. The points discussed here will guide you as you dig deeper to understand the structures and formations of polymers. In case you need help with your biology assignment, our professional writers are more than ready to assist. All you need to do is place an order today.