Biology Chapter 3: Organic Molecules

Comprehensive vocabulary flashcards covering organic chemistry concepts, functional groups, and the four main classes of biomolecules from the Chapter 3 Biology lecture notes.

Organic molecules

Molecules that contain both carbon and hydrogen atoms.

Biomolecules

The four classes of organic molecules found in living organisms: carbohydrates, lipids, proteins, and nucleic acids.

Hydroxyl

A polar functional group that forms hydrogen bonds and is present in sugars and some amino acids.

Carbonyl

A polar functional group present in aldehydes (e.g., formaldehyde) and ketones (e.g., acetone) found in sugars.

Carboxyl

A polar and acidic functional group found in fatty acids and amino acids.

Amino

A polar and basic functional group (Amine) that forms hydrogen bonds and is present in amino acids.

Sulfhydryl

A functional group (Thiol) that forms disulfide bonds and is present in some amino acids.

Phosphate

A polar and acidic functional group (Organic Phosphate) present in nucleotides and phospholipids.

Isomers

Organic molecules that have identical molecular formulas but different arrangements of atoms.

Monomer

A repeating unit that serves as the building block of a biomolecule.

Polymer

A molecule composed of many repeating units called monomers.

Dehydration reaction

A chemical reaction where subunits are joined together by a covalent bond and water is produced; used to connect monomers into polymers.

Hydrolysis reaction

A chemical reaction where a water molecule is added to break a covalent bond; used to break down polymers into monomers.

Enzymes

Specialized molecules that act as catalysts to speed up chemical reactions without being consumed or changed by the reaction.

Carbohydrates

Biomolecules used as an energy source and structural material, containing carbon, hydrogen, and oxygen atoms in a $1:2:1$ ratio.

Monosaccharide

A single sugar molecule (simple sugar) with a backbone of 3 to 7 carbon atoms; examples include glucose, fructose, and galactose.

Disaccharide

A molecule containing two monosaccharides joined together during a dehydration reaction, such as lactose, sucrose, or maltose.

Polysaccharide

A polymer of monosaccharides; examples include starch, glycogen, cellulose, chitin, and peptidoglycan.

Starch

A polysaccharide that serves as an energy-storage molecule in plants.

Glycogen

A polysaccharide that serves as an energy-storage molecule in animals.

Cellulose

The most abundant organic molecule on Earth, found in plant cell walls and indigestible by most animals.

Chitin

A structural polysaccharide found in the cell walls of fungi and the exoskeletons of some animals.

Peptidoglycan

A structural polysaccharide found in the cell walls of bacteria where monomers contain an amino acid chain.

Lipids

Large, nonpolar molecules that are insoluble in water and function in long-term energy storage, structural components, and protection.

Triglycerides

Fats and oils composed of one glycerol molecule linked to three fatty acids by dehydration synthesis.

Unsaturated fatty acids

Fatty acids with one or more double bonds between carbons, typically liquid at room temperature.

Saturated fatty acids

Fatty acids with no double bonds between carbons, typically solid at room temperature.

Phospholipids

Membrane components consisting of one glycerol molecule linked to two fatty acids (hydrophobic tails) and a modified phosphate group (hydrophilic head).

Steroids

Lipids composed of four fused carbon rings, such as cholesterol, testosterone, and estrogen.

Waxes

Long-chain fatty acids connected to carbon chains containing alcohol functional groups, used for protection and waterproofing.

Proteins

Polymers of amino acids linked together by peptide bonds.

Peptide bond

The covalent bond that joins two or more amino acids together.

Polypeptide

A long chain of amino acids joined together.

Denaturation

The process where a protein loses its proper shape and function due to exposure to chemicals, pH changes, or high temperature.

Primary structure

The linear sequence of amino acids in a protein.

Secondary structure

The level of protein structure characterized by alpha helices and beta pleated sheets held by hydrogen bonds.

Tertiary structure

The overall three-dimensional shape of a polypeptide stabilized by hydrophobic interactions and various types of bonding.

Quaternary structure

The level of protein structure that occurs when two or more folded polypeptides interact.

Chaperone proteins

Proteins that assist new proteins in folding into their normal shapes and can correct misfolding.

Prions

Misfolded proteins implicated in fatal brain diseases known as TSEs, such as Mad cow disease.

Nucleic acids

Polymers composed of nucleotides, including DNA and RNA.

Nucleotide

The monomer of nucleic acids, consisting of a phosphate, a pentose sugar, and a nitrogen-containing base.

DNA (Deoxyribonucleic acid)

A double-stranded double helix nucleic acid that stores genetic information for replication and protein sequences.

RNA (Ribonucleic acid)

A predominantly single-stranded nucleic acid that performs protein synthesis and gene regulation.

Complementary base pairing

The specific hydrogen bonding in DNA where adenine ($A$) bonds with thymine ($T$) and cytosine ($C$) bonds with guanine ($G$).

ATP (Adenosine Triphosphate)

The energy currency of the cell; a nucleotide with three phosphates where hydrolysis of the terminal bond provides energy for cellular work.