Molecular and Cell Biology - Lecture 4: Sugars

This set of vocabulary flashcards covers the fundamental concepts of carbon chemistry, isomer types, macromolecule synthesis, and the specific structures and functions of various sugars and polysaccharides discussed in the lecture.

Structural Isomers

Compounds that have the same molecular formula but differ in the covalent arrangements of their atoms.

Cis-trans Isomers

Isomers that differ in arrangement about a double bond; the cis isomer has atoms on the same side, while the trans isomer has them on opposite sides.

Enantiomers

Molecules that are mirror images of each other and differ in spatial arrangement around an asymmetric carbon; they are often designated as L and D isomers.

Macromolecules

Large polymers, such as proteins, nucleic acids, and polysaccharides, that typically contain thousands of atoms.

Polymer

A long molecule consisting of many small molecules of one type linked together by covalent bonds.

Monomer

The small building-block molecules that serve as the subunits of polymers.

Dehydration Reaction

A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water ($H_2O$) molecule.

Hydrolysis

A chemical process that breaks bonds between monomers by the addition of a water ($H_2O$) molecule.

Monosaccharides

The simplest sugars and building blocks for larger molecules, with glucose being the most abundant in biological systems.

Disaccharide

A molecule consisting of two monosaccharides linked together by a glycosidic linkage.

Glycosidic Linkage

A covalent bond formed between two monosaccharides through a dehydration reaction.

Maltose

A disaccharide formed through a $1-4$ glycosidic linkage of two glucose monomers.

Sucrose

A disaccharide formed through a $1-2$ glycosidic linkage of glucose and fructose.

Cellulose

An unbranched polymer of $\beta$ glucose molecules joined by $1-4$ linkages, forming long strands in plant cell walls.

Starch

A storage polysaccharide in plants consisting of glucose monomers joined by $\text{a}$ (alpha) glycosidic bonds.

Amylose

An unbranched form of starch composed of glucose units linked by $1-4$ bonds, which often form helices.

Amylopectin

A branched form of starch that contains $\text{a}-1,6$ glycosidic bonds at branch points, typically every $20-25$ glucose units.

Glycogen

A storage form of energy in animals that is more highly branched than amylopectin, with branch points every $8-10$ glucose units.

Glycoproteins

Proteins that have oligosaccharides or polysaccharides covalently attached to them, such as the surface spike protein of the COVID-19 virus.

Amino Acid

Organic molecules containing an $\text{a}$-carbon atom, an amino group, a carboxyl group, and a variable side-chain ($R$ group).