The hemiacetal or hemiketal hydroxyl group is below the ring and has the same orientation as the hydroxyl group on the original highest numbered chiral C

The hemiacetal or hemiketal hydroxyl group is above the ring and has a different orientation than the hydroxyl group on the original highest numbered chiral C

The chair conformation is more stable than the boat conformation

β configuration is more stable than α configuration

Glycosidic bonds are divided into α-glycosidic bonds and β-glycosidic bonds (mainly). Glycosides are afraid of acid but not alkali.

First α-naphthol/ethanol and then concentrated sulfuric acid. Purple-red ring at the junction of liquid levels

Concentrated acid first and then resorcinol. Ketose is bright red, aldose is light red

Pentose and phloroglucinol/concentrated hydrochloric acid produce a vermilion substance, and other monosaccharides produce a yellow substance

α-1,4-glucosidic bonds are connected and unbranched. The repeating monosaccharide unit is glucose and the repeating disaccharide unit is maltose.

Turns blue when exposed to iodine

α-1,4-glycosidic bond and α-1,6-glycosidic bond (reason for branching). Branched, the repeating monosaccharide units are glucose and the repeating disaccharide units are maltose and isomaltose

Turns purple when exposed to iodine

Homopolysaccharide (glucose)

(Liver glycogen) stores energy for the entire body, especially nerve cells, and is helpful in maintaining the stability of blood sugar concentration under starvation.

(muscle glycogen) stores energy only for muscle cells

(Kidney glycogen) stores energy for the entire body, but only in a limited proportion

Short-term energy reserves. The highly branched structure facilitates its rapid mobilization or resynthesis in the body.

Homopolysaccharide (glucose)

A linear, unbranched molecule connected by β-1,4-glycosidic bonds. The repeating monosaccharide unit is glucose and the repeating disaccharide unit is cellobiose.

The fully extended ribbon conformation has intra-bond, inter-chain, and inter-lamellar hydrogen bonds, which gives cellulose a certain strength.

Most animals have difficulty utilizing β-1,4-glycosidic bonds because the hydrolases in their digestive tract cannot recognize them; archaea or bacteria in the digestive tracts of ruminants and termites can secrete β-glycosidase to hydrolyze cellulose.

Homopolysaccharide (glucose)

Parallel arrangement (the reducing ends of the lamellar chains are on one side, and the non-reducing ends are on the other side)

Linear unbranched, extended ribbon conformation. Found in insect skeletal muscles and fungal cell walls

β-1,4-glycosidic bond

Homopolysaccharide (N-acetylglucosamine: NAG)

Full parallel arrangement, full anti-parallel arrangement, mixed arrangement

The main component of hemicellulose in plant cell walls

β-1,4-glycosidic bond

Homopolysaccharide (xylose)

Heteropolysaccharides with repeating disaccharide units hexuronic acid and hexosamine (except keratin)

Hyaluronic acid (hyaluronic acid)

Keratan sulfate

Chondroitin sulfate

Dermatan sulfate

heparin

Contains sulfate groups, which can covalently bond with core proteins to form proteoglycans

heteropolysaccharides