Biochemical Concepts - AP Biology

Arthropods use the polysaccharide chitin to build their exoskeletons. Certain types of fungi also use chitin instead of cellulose for building their cell walls.

Body fat, also known as triglycerides or triacylglycerols have three fatty acid chains. These hydrocarbon tails are hydrophobic, and they are each attached to the glycerol head, which is hydrophilic via ester linkages. Adipose tissue is a type of connective tissue that plays a structural and protective role, provides stored energy, and helps regulate body temperature.

A fat is a lipid with three fatty chains linked by an ester linkage to glycerol.

A fatty acid consists of a hydrocarbon chain (carbons bound to hydrogen), with even numbers of carbons from 4 to 28, and a carboxyl group at one end. A triglyceride consists of three fatty acids with their carboxyl end bound to glycerol via an ester bond.

Proteins consist of the elements nitrogen, carbon, hydrogen, and oxygen. They are polymers of molecules called amino acids. Lipids are made up of glycerol and fatty acid chains.

All amino acids have an amino group and a carboxyl group. Amino acids do not have glycerol. The side chain called an R-group is what differentiates amino acids from each other in their chemical properties and functions.

Chitin is a type of polysaccharide that is present in the exoskeletons of arthropods, and is the primary substance of the cell wall of fungi. In general, polysaccharides are chains of simple sugars. Another example of a polysaccharide is starch. Waxes are types of lipids. Hemoglobin is a protein, which is made of amino acids. DNA is a nucleic acid, which is a polymer of nucleotides.

A saturated fat contains no double bonds in its fatty acid chain. Just remember that saturated means the fat is saturated with hydrogens. Double bonds eliminate two hydrogen atoms per occurrence, and are present in unsaturated fats.

An amino acid is the monomer unit of the polymer known as a polypeptide. Polypeptide chains form the primary structure of proteins.

A monosaccharide is the simplest unit of a carbohydrate; a monosaccharide dimer is a disaccharide. Triglycerides are a simple form of lipid and nucleic acids are primarily composed of nucleotide monomers.

Lipids are a large class of hydrocarbon-based molecules that includes waxes, steroids, phospholipids and fats. Lipids are hydrophobic and have functions in energy storage, providing support to the cell/organism, cell signaling, and make up the majority of the cell membrane.

Monosaccharides such as fructose are carbohydrates not lipids. Waxes, steroid hormones such as testosterone, estrogen and progesterone, and triglycerides (fats) are composed mainly of hydrocarbons and are classified as lipids.

Glycogen is a carbohydrate. It is a polysaccharide that animals use to store glucose when sugars are needed by the body for fuel. All other answer choices are lipids.

Chitin is a carbohydrate. Specifically, it is a polysaccharide used by arthopods to build exoskeletons, and is found in the cell walls of fungi. Waxes are types of lipids, and nucleic acids are DNA and RNA.

Monosaccharides are the smallest unit of carbohydrates. A disaccharide is made up of two monosaccharides joined together. A string of monosaccharides linked together is a polysaccharide.

Chitin is a structural polysaccharide used by arthropods to build their exoskeletons. Chitin is also found in fungi as well. Cellulose is the structural component found in the cell walls of plants.

Arthropods use the polysaccharide chitin to build their exoskeletons. Certain types of fungi also use chitin instead of cellulose for building their cell walls.

Carbon is phenomenally important to life as we understand it. The ability to form bonds with up to four different atoms gives carbon an incredible chemical diversity, and allows for carbon to make long chains and aromatic compounds. The ability to make long chains and aromatic compounds accounts for the formation of nucleic acids, proteins, and lipids (macromolecules that are absolutely essential to life). Binding properties of carbon also relate to the structure and orientation of biological compounds, which are important aspects of organic chemistry.

In its ground state carbon has four valence electrons, two its full s subshell and two in a partially filled p subshell. Normally, this would indicate that carbon forms two bonds, since only two of the electrons are in orbitals that are not already paired. Carbon, however, is able to form hybrid orbitals by combining the three p orbitals and one s orbital to form four identical sp3 orbitals, each containing one electron. This means that carbon can form four bonds, allowing it to achieve a stable octet.

For biology, the important note is that carbon can make four bonds. Organic chemistry is the study of carbon and how these bonds function to create organic and biological materials.

The chemical properties of an element are, in a large part, determined by the number of bonds that element can form with other elements. Silicon, like carbon, can form four bonds with other elements, and thus is the most similar. This can easily be seen on a periodic table as elements with similar properties are grouped together in the same column. Note that these similarities arise from having the same number of valence electrons.