Biological molecules | Biology Biological Principles
-Fatty acids are the monomers for lipids, for example, and regardless of how they are bonded (as a saturated or unsaturated fat, for example). (redox) reactions from a biology point of view, see this Khan Academy video. The 3 types of macromolecules (very large molecules) are polysaccharides, Polymerization of monomers into polymers occurs by dehydration reactions . sugar-phosphate + nitrogenous base) in a phosphodiester linkage. Start studying 4. khan macromolecules. Like starch, glycogen is a polymer of glucose monomers, and it is even more highly branched . glycosidic linkage.
Up to the early 19th century, scientists thought only living organisms could make organic compounds. Organic compounds are all built from carbon atoms, but not all molecules containing carbon are organic. So how do we recognize organic molecules? Organic molecules can arise naturally from abiotic synthesis see Miller-Urey exptbut in the biosphere, most organic molecules are synthesized by living organisms.
Synthesis of organic carbon molecules from inorganic CO2 requires energy and chemical reducing power, as the carbon atoms in organic molecules are in reduced form. For a review of oxidation-reduction redox reactions from a biology point of view, see this Khan Academy video. Briefly, atoms such as carbon or oxygen are said to be reduced if they form covalent bonds with an atom with lesser electronegativity, such as hydrogen. Conversely, carbon is oxidized when it forms a covalent bond with an atom with greater electronegativity, such as oxygen.
Recall that a covalent bond is formed when two atoms share a pair of electrons. The reduced atom has gained a majority share of the electrons that form the covalent bond, and the oxidized atom has only a minority share.
The biomass of a cell the organic contents, excluding water and inorganic salts is composed of 3 types of macromolecules plus lipids. Students should know how cells make these macromolecules, and their basic structures and functions.
Introduction to carbohydrates
Small organic molecules are covalently linked polymerized to form the 3 types of large biological macromolecules polymers ; lipid membranes self-assemble. One recent study concluded that cells are composed of 68 distinct organic molecules http: Polymerization of monomers into polymers occurs by dehydration reactions — linking two subunits together via a covalent bond extracts an -OH and a H to create a molecule of water: So dehydration reactions remove a molecule of water from the starting molecules in the process of forming a covalent bond between the molecules.
Cleavage of polymers back to monomers occurs by hydrolysis reactions — a molecule of water is split hydrolyzed to -OH and H and used to break the bond linking two subunits. This is exactly the reverse of a dehydration reaction. See the diagrams below on glycosidic bonds and peptide bonds to see how water molecules are created or used in these reactions. Lipids in water can spontaneously aggregate via hydrophobic interactions to form lipid bilayer membranes.
Hydrophobic interactions arise from nonpolar molecules avoiding water — having all the nonpolar molecules associate together minimizes their interaction with water.
Introduction to macromolecules (article) | Khan Academy
How can we predict whether an organic molecule will be hydrophobic a lipid or hydrophilic? If the molecule has negatively or positively charged atoms is ionizedor has a high proportion of polar bonds C-O or C-Nthen the molecule is hydrophilic.
If the molecules has mostly non-polar bonds C-H or C-Cthen it is hydrophobic. Below are descriptions of the 3 types of macromolecules and lipid membranes: Examples are starch, cellulose, and chitin. Monosaccharides are organic molecules with the composition [CH2O]n, where n is usually Examples are 6-carbon sugars like glucose, and 5-carbon sugars like ribose. Carbohydrates may refer either to monosaccharides of the composition [CH2O]n, or to polysaccharides. Complex carbohydrates often have branched structures.
Glycosidic bonds between monosaccharides form via dehydration reactions. It's one simple sugar right over here. And we would call this glycogen a polysaccharide. Or another way to think about it is glucose is the building block for the glycogen. Another term you might see is monomer and polymer. Those are the general terms or if I'm building a large molecule out of a chain of smaller ones, the building blocks, we consider to be monomers, and then the thing that we build out of those monomers could be our polymer.
And as we'll see, this monomer polymer phenomenon is not limited to carbohydrates or saccharides. We're gonna see that same relationship, for example, between amino acids and proteins. Now, what role do carbohydrates play inside of biological systems? Well, saccharides or carbohydrates are often associated with the source energy. Glucose can be converted very quickly to energy in biological cells. Glycogen is also a store of energy in your liver and your muscles.
And once again, it can be broken down into the glucose molecules, which once again, is a very readily available source of energy. Now, in plants especially, some of these polysaccharides could also play a structural role if we're talking about things like cellulose, which is another polysaccharide.
How are monomers, polymers and macromolecules related?
So, there's also a structural role. Now, I will leave you there. We have focused only on one type of monosaccharide in glucose, and only on one type of polysaccharide in glycogen. As we will see, glucose does show up a lot but there are many other types of monosaccharides and there are many other types of polysaccharides. And polysaccharides in particular are part of a broader group of molecules known as macromolecules. And as you can imagine, from the macro prefix, it's referring to large molecules, oftentimes that have thousands of atoms in them.
But don't get the wrong idea.