Biological Molecules Vocabulary

Vocabulary terms and definitions extracted directly from Chapter 1: Biological Molecules lecture transcript.

Biochemistry

The branch of biology which explains the biochemical basis of life.

Protoplasm

The living matter inside a cell, chemically containing $700\%$ to $90\%$ water ($H_2O$).

Dry Weight

The remaining mass of a cell after all water has evaporated, consisting mostly of biomolecules.

Biomolecules

Carbon-containing long-chain organic molecules produced by living organisms, synthesized mainly from carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulphur.

Condensation (Dehydration Synthesis)

The process of joining two monomers by removing an $-OH$ group from one monomer and an $H$ atom from another to form a covalent bond with energy expense and enzyme activity.

Hydrolysis

The breakdown of macromolecules into their monomer subunits by the addition of a water molecule ($H_2O$), releasing energy.

Cohesive force of attraction (Cohesion)

The attractive force between similar molecules, such as polar water molecules attracting each other to form hydrogen bonds.

Adhesive force of attraction (Adhesion)

The attractive force between dissimilar molecules, such as water molecules attracting other charged surfaces.

Specific heat

The amount of heat energy required to raise the temperature of $1\,gm$ of a substance by $1^\circ\text{C}$.

Heat of vaporization

The amount of heat required to change a substance from a liquid state to a vapor state, equal to $574\,kcal/kg$ for water.

Hydrophobic exclusion

The tendency of water molecules to form hydrogen bonds with each other and exclude nonpolar, hydrophobic substances like oil, forcing them to clump together.

Carbohydrates

Polyhydroxy carbonyl compounds (aldehydes or ketones) synthesized primarily by plants during photosynthesis, with the general formula $C_n H_{2n} O_n$.

Monosaccharides

Carbohydrates containing only one sugar molecule with the empirical formula $C_n H_{2n} O_n$ that cannot be hydrolyzed.

Oligosaccharides

Carbohydrates made up of 2 to 10 monosaccharides linked covalently by glycosidic bonds.

Reducing sugar

A carbohydrate with a free aldehyde or ketone group that is capable of being oxidized and reducing other substances without prior hydrolysis.

Non-reducing sugar

A carbohydrate lacking a free aldehyde or ketone group that cannot be oxidized and does not reduce other substances (e.g., sucrose).

Polysaccharides

High molecular weight carbohydrates formed by the condensation of hundreds or thousands of monosaccharide units.

Starch

The primary reserve food material of higher plants, made of straight-chain amylose and branched-chain amylopectin, which gives a blue color with iodine.

Glycogen

A branched polymer of glucose stored in animal liver and muscles as well as fungi and bacteria, commonly called animal starch, which turns red with iodine.

Cellulose

An insoluble straight-chain polymer of glucose forming plant cell walls that gives no color with iodine and is undigestible in humans.

Chitin

A nitrogen-containing modified polysaccharide polymer of N-acetyl glucosamine ($(C_8 H_{13} O_5 N)_n$) present in fungal walls and arthropod exoskeletons.

Proteins

Complex nitrogenous organic polymers composed of specific sequences of amino acids linked by peptide bonds that execute cellular functions.

Amino acids

Organic compounds containing at least one basic amino group ($-NH_2$) and one acidic carboxylic acid group ($-COOH$) bonded to an asymmetric $\alpha$-carbon.

Peptide bond

A covalent linkage formed between the carboxyl group of one amino acid and the amino group of another with the release of one water molecule.

Fibrous Proteins

Insoluble, non-crystalline, and elastic proteins consisting of long intertwining polypeptide fibrils that serve structural roles.

Globular Proteins

Spherical or ellipsoidal three-dimensionally folded proteins that are soluble in aqueous media and act as functional molecules such as enzymes, antibodies, and hormones.

Lipids

A diverse group of biological molecules proposed by Bloor (1943) that are insoluble in water but soluble in organic solvents like ether and alcohol.

Acylglycerol

Esters formed by the condensation of glycerol (a trihydroxy alcohol) with three fatty acids via esterification.

Phospholipid

A amphipathic lipid made of glycerol condensed with two fatty acids, a phosphate group, and choline, forming hydrophobic tails and a hydrophilic head.

Waxes

Hydrophobic, chemically inert esters of long-chain mono-alcohols and long-chain fatty acids that serve as protective coatings.

Terpenoids

A large class of lipids built from repeating isoprenoid units ($C_5 H_8$), including terpenes, steroids, carotenoids, and prostaglandins.

Steroids

Terpenoids featuring a steroid nucleus made of 17 carbon atoms arranged in four fused rings (three hexagonal and one pentagonal).

Prostaglandins

A group of lipids synthesized by mammalian tissues at injury sites that regulate processes such as inflammation, pain perception, and blood clotting.

Nucleic Acids

High molecular weight linear polymers composed of nucleotides (DNA and RNA) that manage genetic information and protein synthesis.

Nucleotide

The monomer of nucleic acids, consisting of a pentose sugar, a nitrogenous base attached to carbon 1', and a phosphate group attached to carbon 5'.

Nucleoside

A structure composed of a pentose sugar covalently attached to a nitrogenous base without a phosphate group.

Phosphodiester bond

The covalent bond linking the $3'\text{-carbon}$ of one pentose sugar to the $5'\text{-carbon}$ of another via a phosphate group, forming the backbone of nucleic acid strands.

Gene

A specific sequence or segment of DNA that contains the functional hereditary information required to synthesize a specific protein or enzyme.

Transcription

The first step of protein synthesis in which genetic code information from a DNA gene is copied into messenger RNA (mRNA).

Translation

The process where mRNA binds to a ribosome and is translated by tRNA and rRNA into a specific amino acid sequence.

Conjugated Molecules

Complex molecules formed by the chemical combination of two different groups of biomolecules acting as a single unit.