Identify structure and purpose of carbohydrates, lipids, proteins, and nucleic acids - AP Biology

Fat is made up of glycerol and fatty acids. Specifically, a fat is composed of three fatty acids chains—composed of 16 or 18 carbon atoms in length—connected to a glycerol by way of an ester linkage.

A saturated fatty acid has no double bonds between the carbon atoms making up the tail of the fatty acid. This lack of double bonding allows for as many hydrogen atoms as possible to be bonded to the carbon skeleton, thus the fatty acid is said to be saturated with hydrogen atoms.

An unsaturated fatty acid has one or more double bonds in its hydrocarbon tail. These double bonds are formed by the removal of hydrogen atoms from the carbon tail, resulting in a kink in the tail. As such, they are not fully saturated with hydrogen atoms. Cholesterol is a type of lipid that contains four hydrocarbon rings in its structure. Hydrogenated fatty acids are unnatural saturated fatty acids that are modified for their physical properties.

A triacylglycerol (also called commonly referred to as a fat or a triglyceride) is composed of three fatty acid chains linked to glycerol via an ester linkage. The fatty acids can be the same or two or three different types. Steroids are derived from cholesterol, a molecule that contains four hydrocarbon rings attached together. Phospholipids only have two fatty acid tails linked to a glycerol head and a phosphate group.

Triacylglycerol (also called a fat or triglyceride) is a type of lipid. Amino acids are the subunits that make up proteins. Chitin and cellulose are polysaccharides, or carbohydrates.

Earth's early atmosphere contained carbon, (methane), (ammonia), and , but no oxygen.

Polymers of amino acids are called polypeptides. A protein is made up of one or more polypeptide chains that has folded and coiled in specific 3D configurations. Nucleic acids are polymers of nucleotides. Examples of nucleic acids are RNA and DNA. Ribosomes are the site of protein synthesis and are made of rRNA and protein.

Conformation is the the term for the three dimensional structure of proteins. Though the types of proteins are incredibly diverse they are all polymers made up of the same set of 20 amino acids. A protein's molecular weight involves the sum of all the atoms and their abundances, molecular weight is often used to approximate the size of a protein when determining if it will pass through a pore or channel in a membrane. The amino acid sequence is the primary structure, and is held together by peptide bonds.

All proteins are made up of amino acids. Even though proteins are highly diverse they all can be built from the same set of 20 amino acids. Thus, the order in which these amino acids are linked together (primary structure, which is directly determined by the DNA sequence) determines its structure and function.

Amino acids are made up of carboxyl and amino groups. Hence their name, amino acids describes the functional groups found in all proteins, regardless of their R-groups. Carboxyl groups are also known as carboxylic acid groups. Glycerol is found in lipids, specifically fats where it is linked to fatty acid chains. Hydroxyl groups are also known as alcohol groups and are not present in all amino acids, although, some R-groups contain hydroxyl functional groups.

The covalent bond between two amino acids is called a peptide bond. This is formed by positioning two amino acids so the carboxyl group of one is adjacent to the amino group of another. An enzyme then joins the two via a dehydration synthesis reaction. Ester bonds link fatty acids to glycerol heads, and phosphodiester bonds are formed between the sugar and phosphate backbone of a nucleic acid.

The primary structure of a protein is its amino acid sequence. The coils and folds of a protein are its secondary structure. Irregular contortions in the protein structure due to interactions between amino acid side chains is the tertiary structure. The overall structure when two or more polypeptides aggregated is the quaternary structure.

Disulfide bonds may be formed in both tertiary and/or quaternary structures of a protein. These bonds result from the oxidation of the R-group (side chain) of the amino acid cysteine.

Structurally speaking, a triglyceride molecule contains three fatty acid chains covalently bonded to glycerol—specifically where the hydroxyl groups are located on the glycerol molecule.

The linear sequence of amino acids in a polypeptide chain gives rise to the protein's primary structure.

RNA stands for ribonucleic acid, and each RNA nucleotide contains one phosphate, one nitrogenous base (either adenine, uracil, cytosine, or guanine), and one ribose sugar. RNA does not contain a deoxyribose sugar as seen in DNA.

The formation of disulfide bridge occurs in the tertiary and/or quaternary level of protein structure. This involves two sulfur atoms sharing a lone pair of electrons to form a covalent bond, which enhances the integrity of the protein's structure. The amino acid that is involved in forming disulfide bridges is cysteine.

The term saturated when describing a lipid means that a molecule has the maximum number of hydrogens on its carbons, it is saturated with hydrogens. An unsaturated lipid has less than the maximum amount of hydrogens bonded to its carbons because there is a double bond between two of the carbons. Lipids molecules can have one carbon to carbon double bond (mono-unsaturated) or multiple (poly-unsaturated).

Nucleotides are linked together to form nucleic acids by bonds between the phosphate groups and ribose sugars. A phosphate group is bonded the 5' carbon of one ribose and the 3' carbon of the next ribose, leading to the 5' to 3 directionality of DNA.