Biological Molecules – Topic 3 Practice Flashcards

These vocabulary flashcards cover the importance of carbon, functional groups, monomers, polymers, and the four major biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids) as detailed in Topic 3.

Organic compounds

Compounds that contain carbon bonded to carbon ($C$) or hydrogen ($H$).

Carbon chains

The skeletons of organic molecules.

Tetravalent

A property of carbon having $4$ valence $e^-$ which allows it to form four covalent bonds.

Functional group

A group of atoms with a specific structure that allows for specific molecular functions.

Hydrocarbons

Molecules consisting of carbon and hydrogen (e.g., methane $CH_{4}$) that are nonpolar, uncharged, hydrophobic, and insoluble in $H_{2}O$.

Hydroxyl group

($R-OH$) A polar and hydrophilic functional group known as an alcohol (names typically end in –ol) which is neutral in acidity.

Carbonyl group

($CHO$) A polar and hydrophilic functional group found in sugars, categorized as either an aldehyde or ketone depending on the location of the $C=O$ bond.

Carboxyl group

($R-COOH$) A polar, hydrophilic, and acidic functional group that easily releases $H^{+}$; found in amino acids and fatty acids.

Amino group

($R-NH_{2}$) A polar and hydrophilic functional group that acts as a base by easily accepting $H^{+}$; found in amino acids.

Phosphate group

($R-PO_{4}H_{2}$) A polar, hydrophilic, and acidic functional group that often contributes a negative charge; found in phospholipids, nucleic acids, and $ATP$.

Methyl group

($R-CH_{3}$) A nonpolar, hydrophobic hydrocarbon group that is neither an acid nor a base; involved in the control of gene expression and the shape/function of sex hormones.

Monomers

The individual building blocks used to form macromolecules.

Polymers

Large molecules formed by joining monomers together in repeated patterns; examples include carbohydrates, proteins, and nucleic acids.

Dehydration synthesis

The process of joining monomers to make a polymer by removing a water ($H_{2}O$) molecule, facilitated by enzymes called dehydrogenases.

Hydrolysis

The process of breaking a polymer into monomers by adding a water ($H_{2}O$) molecule, facilitated by enzymes called hydrolases.

Carbohydrates

Molecules with the general formula $CH_{2}O$ (such as glucose $C_{6}H_{12}O_{6}$) that serve as fuel and building material.

Glycosidic linkage

The covalent bond formed between monosaccharides.

Storage Polysaccharides

Sugar polymers used for energy storage, such as starch (amylose) and glycogen.

Structural Polysaccharides

Sugar polymers used for structural support, such as cellulose and chitin.

Lipids

A family of hydrophobic biological molecules that are primarily hydrocarbons and are not considered polymers; includes fats, phospholipids, and steroids.

Ester linkage

The covalent bond formed between a fatty acid and glycerol through dehydration synthesis to create a triglyceride.

Saturated fatty acid

A fat molecule with no double bonds between carbon atoms.

Unsaturated fatty acids

Fat molecules that contain one or more double bonds, categorized as cis or trans.

Amphipathic

A molecule having both a hydrophilic region and a hydrophobic region, such as a phospholipid.

Steroids

Lipids characterized by a carbon skeleton consisting of three rings of $6$ carbons and one ring of $5$ carbons; examples include cholesterol and cortisol.

Peptide bonds

Covalent bonds that join the carboxyl group of one amino acid to the amino group of the next amino acid.

Primary structure

The specific sequence of amino acids in a polypeptide chain as determined by $DNA$.

Secondary structure

The stabilization of a polypeptide into an $\alpha$ helix (coil) or $\beta$ pleated sheet via hydrogen bonds between the amino and carboxyl groups.

Tertiary structure

The particular $3-D$ shape of a single polypeptide chain formed by interactions between R-groups.

Quaternary structure

The macromolecular structure resulting from the association of multiple polypeptide chains.

Denaturation

The loss of a protein’s tertiary or quaternary structure, rendering it biologically inactive; caused by changes in $pH$, salt concentration, or temperature.

Nucleotides

The monomers of nucleic acids ($DNA$ and $RNA$) that transmit hereditary information.

Phosphodiester bond

The bond that holds nucleotide monomers together in a nucleic acid chain.