2c - Biological Molecules

Carbohydrates

碳水化合物 (tànshuǐ huàhéwù) / 糖类 (tánglèi) Molecules like sugars and starch (made of C, H, O); used for energy.

Lipids

脂质 (zhīzhì) / 脂肪 (zhīfáng) Fats and oils; made of fatty acids and glycerol; used for energy storage and insulation.

Proteins

蛋白质 (dànbáizhì) Large molecules made of chains of amino acids; have many functions (e.g., enzymes, growth, repair).

Glucose

葡萄糖 (pútáotáng) A simple sugar (monosaccharide); the main fuel for respiration.

Lactose

乳糖 (rǔtáng) Milk sugar; a disaccharide made of glucose and galactose.

Fructose

果糖 (guǒtáng) Fruit sugar; a monosaccharide.

Sucrose

蔗糖 (zhètáng) Table sugar; a disaccharide (glucose + fructose); transported in plant phloem.

Maltose

麦芽糖 (màiyátáng) Malt sugar; a disaccharide made of two glucose molecules.

Starch

淀粉 (diànfěn) A polysaccharide (many glucose units); energy storage in plants.

Glycogen

糖原 (tángyuán) A polysaccharide (many glucose units); energy storage in animals and fungi.

Cellulose

纤维素 (xiānwéisù) A polysaccharide (many glucose units); forms plant cell walls, providing strength.

Monosaccharides

单糖 (dāntáng) Single sugar units (e.g., glucose, fructose); building blocks for larger carbohydrates.

Disaccharides

二糖 (èrtáng) Sugars made of two monosaccharides linked together (e.g., sucrose, lactose).

Polysaccharides

多糖 (duōtáng) Large carbohydrates made of many monosaccharide units linked together (e.g., starch, glycogen, cellulose).

Fatty acids

脂肪酸 (zhīfángsuān) Molecules that, with glycerol, are building blocks of lipids.

Glycerol

甘油 (gānyóu) A molecule that, with fatty acids, forms lipids.

Amino acids

氨基酸 (ānjīsuān) Building blocks of proteins; about 20 different types.

Test for reducing sugar (glucose)

还原糖（葡萄糖）检测 (huányuán táng (pútáotáng) jiǎncè) Add Benedict's solution, heat. Positive: Blue -> green/yellow/orange/brick-red.

Test for starch

淀粉检测 (diànfěn jiǎncè) Add iodine solution. Positive: Orange-brown -> blue-black.

Test for protein

蛋白质检测 (dànbáizhì jiǎncè) Add Biuret solution. Positive: Blue -> purple/lilac.

Test for lipids

脂质检测 (zhīzhì jiǎncè) Mix with ethanol, then add water. Positive: Forms a white cloudy emulsion.

Peptide bond

肽键 (tàijiàn)  The chemical bond that forms between two amino acids during protein synthesis.

Triglyceride

甘油三酯 (gānyóu sānzhǐ)  A type of lipid composed of one glycerol molecule and three fatty acid molecules; the main form of stored fat in animals.

Phospholipid

磷脂 (línzhī) A type of lipid molecule that is a major component of cell membranes; has a hydrophilic head and two hydrophobic tails.

Water

水 (shuǐ) An essential inorganic molecule for life; acts as a solvent, transport medium, reactant in metabolic processes (e.g., hydrolysis), and helps regulate temperature.