3 - Molecules of Life

Organic

A compound that consists mainly of carbon and hydrogen atoms.

Hydrocarbon

Compound that consists only of carbon and hydrogen atoms.

Condensation

Chemical reaction in which an enzyme builds a large molecule from smaller units and water is formed

Hydrolysis

Water-requiring chemical reaction in which an enzyme breaks a molecule into smaller subunits

Carbohydrate

Molecule that consists primarily of carbon, hydrogen, and oxygen atoms in a 1:2:1 ratio

Monosaccharides

Simple sugar; consists of one sugar unit so it cannot be broken apart into monomers

Examples of monosaccharides

Glucose, fructose, galactose

Oligosaccharide

Short chains of covalently bonded monosaccharides

Disaccharide

Carbohydrate that consists of two monosaccharide monomers

Examples of disaccharides

Sucrose: glucose+sucrose

Lactose: glucose+galactose

Maltose: glucose+glucose

Polysaccharide

Carbohydrate that consists of hundreds or thousands of monosaccharide monomers

Cellulose

Crosslinked polysaccharide of glucose monomers; the major structural material in plants

Chitin

Nitrogen-containing polysaccharide that composes fungal cell walls and arthropod exoskeletons

Glycogen

Highly branched polysaccharide of glucose monomers. Principal form of stored sugars in animals.

Starch

Polysaccaride - energy reservoir in plant cells

Lipid

Fatty, oily, or waxy organic compound

Fatty acid

Lipid that consists of an acidic carboxyl group “head” and a long hydrocarbon “tail”

Triglyceride

A molecule that is entirely hydrophobic and therefore does not dissolve in water. Most abundant and richest energy source in your body and is more energy-dense than carbs.

Has three fatty acids bonded to a glycerol.

Fat

A triglyceride molecule

Saturated fat

Triglyceride molecule with three saturated fatty acid tails.

Their floppy tails pack together tightly, so they are sold at room temperature.

They only have single bonds linking the carbons in their tails.

Unsaturated fat

Triglyceride molecule with one or more unsaturated fatty acid tails.

Double bonds between carbons kink the tail of an unsaturated fatty acid and limit its flexibility. This is why undaturated fats are liquid at room tempearture.

Monounsaturated fat

Has one double bond among its three tails

Polyunsaturated fat

Has two or more double bonds among its three tails

Trans fat

A type of unsaturated fat, but solid at room temperature because of a special trans double bond that keeps the tails straight.

Phospholipid

A lipid with two hydrophobic fatty acid tails and a hydrophilic phosphate group in its head

Lipid bilayer

Formed by phospholipids; double layer of lipids arranged tail-to-tail and structural foundation of cell membranes

Steroids

Lipids with no fatty acid tails. Instead they have four carbon rings.

Eg cholesterol, steroid hormones.

Wax

A water-repellent substance that consists of a complex, varying mixture of lipids with long fatty acid tails bonded to long-chain alcohols.

Waxes are waterproof because they pack together very tightly.

Amino acid

Small organic compound that is a monomer of proteins. Consists of an amine group (—NH2), a carboxyl group (—COOH, the acid), and one of 20 “R” groups that defines the kind of amino acid, all typically bonded to the same carbon atom.

Peptide

Short chain of amino acids linked by peptide bonds

Peptide bond

The covalent bond that links amino acids in a protein. Joins the amine group of one amino acid and the carboxyl group of another.

Polypeptide

Long chain of amino acids linked by peptide bonds

Protein

Organic molecule that consists of one or more polypeptides folded into a specific shape

Protein primary structure

Linear sequence of amino acids.

Secondary structure

Helices and sheets. These patterns arise when hydrogen bonds that form between amino acids make the polypeptide twist and turn.

Tertiary structure

Functional domains formed by interactions between helices and sheets that make them fold up together.

Quaternary structure

An association of multiple polypeptides.

Denaturation

When a protein has its hydrogen bonds, which maintain the shape of a protein, disrupted by shifts in pH or temperature or by exposure to detergents or salts, and a protein loses its secondary, tertiary, and quaternary structure.

Eg. When you cook an egg, you denature the protein in the egg white.

Prion

Infectious protein that causes other normally folded proteins to misfold too.

Lipoprotein

Protein that can bind to lipids. They form particles that allow fats and other hydrophobic molecules to move through watery fluid into cells and bodies.

Glycoprotein

A protein with one or more oligosaccharides attached to it. They allow a tissue or a body to recognize its own cells.

Nucleotides

Small molecule with a five-carbon sugar, a nitrogen-containing base, and phosphate groups. Monomer of nucleic acids.

Function as energy carriers, enzyme helpers, chemical messengers, and subunits of DNA, and RNA.

ATP

Adenosine triphosphate. Nucleotide monomer of RNA and an important energy carrier in cells.

Nucleic acid

Polymer of nucleotides. DNA or RNA.

Sugar of one nucleotide is joined to the phosphate group of the next.

RNA

Ribonucleic acid. Single chain of nucleotide monomers. Carries out protein synthesis

DNA

Deoxyribonucleic acid. Nucleic acid that carries hereditary information.