Proteins, Carbohydrates, and Lipids

Flashcards covering the classification, structures, and functions of macromolecules including proteins, carbohydrates, and lipids as discussed in the lecture notes.

Polymer

A long molecule consisting of many similar building blocks called monomers.

Monomer

Small building-block molecules that link together to form polymers.

Condensation Reactions

Reactions that link small molecules to form large molecules, requiring energy and resulting in the formation and release of a water molecule.

Hydrolysis Reactions

Reactions that break large molecules into small molecules, releasing energy and requiring the addition of water.

Functional Groups

Groups of atoms with specific properties (such as polarity) that determine the function of a macromolecule.

Isomers

Compounds with the same molecular formula but different structures and properties.

Structural Isomers

Isomers that have different covalent arrangements of their atoms.

Geometric Isomers

Isomers that have the same covalent arrangements but differ in spatial arrangements (e.g., cis and trans isomers).

Enantiomers

Isomers that are mirror images of each other.

Proteins

Molecules consisting of one or more polypeptide chains which are single, unbranched chains of amino acids folded into specific 3-D shapes.

Amino Acids

The building blocks of proteins, containing both carboxyl and amino groups, an $\alpha$ carbon, and a variable side chain (R-group).

Disulfide Bridge

A covalent bond formed between the terminal $-SH$ groups of two cysteine side chains ($-S-S-$), important in protein folding.

Peptide Linkages

Covalent bonds (peptide bonds) that link amino acids together via a condensation reaction.

Primary Structure

The specific sequence of amino acids in a protein's polypeptide chain.

Secondary Structure

Regular structural patterns in a protein, such as the $\alpha$ helix and $\beta$ pleated sheet, resulting from hydrogen bonding between N-H and C=O groups.

Tertiary Structure

The specific 3-D shape of a protein determined by interactions between R-groups, such as disulfide bonds and hydrogen bonds.

Quaternary Structure

The structure resulting from the interaction of two or more polypeptide subunits (e.g., Hemoglobin).

Denatured

A state in which a protein's secondary and tertiary structure breaks down, often due to heating.

Carbohydrates

Molecules with the general formula $(C_1H_2O_1)_n$ that serve as energy sources, transport molecules, and structural components.

Monosaccharides

Simple sugars, such as glucose, which can exist in straight chain or ring forms ($\alpha$ or $\beta$).

Glycosidic Bonds

Covalent bonds formed between monosaccharides through condensation reactions to create disaccharides, oligosaccharides, or polysaccharides.

Cellulose

An unbranched polymer of glucose with $\beta-1,4$ glycosidic bonds that is chemically stable and provides structural strength to plant cell walls.

Starch

A branched polymer of glucose with $\alpha-1,4$ glycosidic bonds used for energy storage in plants.

Glycogen

A highly branched polymer of glucose used for energy storage in animal liver and muscle cells.

Chitin

A polymer of N-acetylglucosamine that forms the external skeletons of insects and provides sites for hydrogen bonding between polymers.

Lipids

Nonpolar hydrocarbons that are insoluble in water and held together in aggregates by van der Waals forces.

Triglycerides

Lipids (fats and oils) composed of three fatty acids and one glycerol molecule bonded by ester linkages.

Saturated Fatty Acid

A fatty acid with no double bonds between carbons, saturated with hydrogen atoms, and typically solid at room temperature.

Unsaturated Fatty Acid

A fatty acid with one or more double bonds in the carbon chain, creating kinks that prevent tight packing and keep them liquid at room temperature.

Phospholipids

Amphipathic molecules containing two fatty acid "tails" (hydrophobic) and a phosphate "head" (hydrophilic) bonded to glycerol.

Phospholipid Bilayer

The structural basis of biological membranes where hydrophobic tails line up together and hydrophilic phosphate heads face outward toward the aqueous environment.

Lipoproteins

Complexes of phospholipids and proteins that transport lipids, such as cholesterol, in the blood.