Biological molecules
Introduced| English | Meaning |
|---|---|
| biological molecules/ˌbaɪəˈlɒdʒɪkl ˈmɒlɪkjuːlz/ | biological molecules |
| carbohydrates/ˌkɑːbəʊˈhaɪdreɪts/ | An organic compound such as a sugar, starch or cellulose, made primarily from carbon, hydrogen and oxygen. |
| proteins/ˈprəʊtiːnz/ | Biological macromolecules made of folded chains of amino acids. |
| lipids/ˈlɪpɪdz/ | A member of a group of largely water-insoluble biological molecules, including fats, oils, phospholipids and steroids. |
| glucose/ˈɡluːkəʊs/ | A simple sugar with molecular formula C6H12O6, used by cells as a source of energy. |
| starch/stɑːtʃ/ | A storage polysaccharide in plants, made from glucose units. |
| glycogen/ˈɡlaɪkədʒn/ | A highly branched glucose polysaccharide used for energy storage in animals and fungi. |
| amino acids/əˈmiːnəʊ ˈæsɪdz/ | Organic molecules with amino and carboxyl groups that link together to make proteins. |
| fatty acids/ˈfæti ˈæsɪdz/ | A carboxylic acid with a hydrocarbon chain, commonly a component of lipids such as triglycerides. |
| glycerol/ˈɡlɪsərɒl/ | A three-carbon alcohol with three hydroxyl groups, forming part of the structure of triglycerides. |
The molecules of life
- Living things are built from a small set of biological molecules 生物分子, made by joining tiny units into big ones.
- Three groups matter most: carbohydrates 碳水化合物, proteins 蛋白质 and lipids 脂质 (fats).
Biological molecules lab
Classify food molecules by their main job in cells.
Carbohydrates are made of which three elements?
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Carbohydrates contain C, H and O.
Many glucose units join together to make the storage carbohydrate ______ in plants.
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Plants store glucose as starch; animals store it as glycogen.
Carbohydrates
- Made of carbon, hydrogen and oxygen.
- Small sugars (like glucose 葡萄糖) join to make large carbohydrates (starch 淀粉, glycogen 糖原, cellulose).
Large molecules are built by joining many small units together
Proteins are built from smaller units called:
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Proteins are chains of amino acids.
Lipids (fats) are made from fatty acids and:
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A lipid is fatty acids joined to glycerol.
Proteins and lipids
- Proteins are long chains of amino acids 氨基酸 — used for growth, repair, enzymes and antibodies.
- Lipids (fats and oils) are made of fatty acids 脂肪酸 and glycerol 甘油 — used for energy storage and insulation.
Starch grains from a potato, seen under a microscope
Proteins contain nitrogen, but carbohydrates and lipids do not.
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The nitrogen in amino acids distinguishes proteins.
Small units, big molecules
- Big molecules are built from small building blocks: sugars → starch, amino acids → proteins, fatty acids + glycerol → lipids.
- The same few elements (C, H, O, and N in proteins) make all of them.
Starch, glycogen and cellulose are all made of glucose. They differ in how the glucose units are joined, which gives each a different job — storage (starch/glycogen) or structure (cellulose).
DNA is a double helix; the bases always pair A-T and C-G
You've got it
- three key groups: carbohydrates, proteins, lipids
- carbohydrates = sugars → starch/glycogen/cellulose; proteins = amino acids; lipids = fatty acids + glycerol
- proteins also contain nitrogen (N), unlike carbohydrates and lipids