Carbohydrates and lipids – building molecules, bonds and functions
BiologyCell BiologyAges 15–16
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Sign in to playBuild molecules from α-glucose and β-glucose (the OH on carbon 1 below or above the ring): condensation forms 1,4 and 1,6 glycosidic bonds and releases water, giving maltose, sucrose, lactose, amylose, amylopectin, glycogen or cellulose, which acid or specific enzymes hydrolyse again. On the lipids screen, join glycerol to three fatty acids by ester bonds to make a triglyceride, compare saturated and unsaturated chains (cis kinks, melting points, omega numbering, iodine number), watch phospholipids with hydrophilic heads and hydrophobic tails form a bilayer in water and run the ethanol emulsion test. A structure–function table sums it up.
Lesson: Carbohydrates and lipids: monomers, glycosidic and ester bonds, structure and function
What it shows
Carbohydrates and lipids are built by condensation and broken down by hydrolysis. α- and β-glucose differ only in the position of the OH group on carbon 1. α-glucose joined by α-1,4 bonds coils into amylose; extra α-1,6 branches give amylopectin and the more highly branched glycogen, both energy stores. β-glucose joined by β-1,4 bonds, with every other unit flipped, forms straight cellulose chains that hydrogen-bond into strong microfibrils. A triglyceride is glycerol plus three fatty acids joined by ester bonds; cis double bonds kink the chains, so unsaturated fats are oils. Phospholipids have a hydrophilic phosphate head and two hydrophobic tails, so they form bilayers in water.
How to use
On 1. Carbohydrates, pick α-glucose or β-glucose and press + α-glucose (1,4 bond), + β-glucose (1,4 bond) or + α-glucose branch (1,6 bond), or choose a molecule under Start from and press Load. Tap a ring to choose where the next unit joins. Choose a Hydrolysing agent, then tap a bridging O or press Hydrolyse all. On 2. Lipids, choose the fatty acids, press Join by condensation (ester bonds), Put many molecules in water and Emulsion test.
Parameters you can change
- Opening screen Carbohydrates, Lipids, Structure–function table
- Selected glucose monomer α-glucose, β-glucose
- Starting molecule One glucose molecule, Maltose, Sucrose, Lactose, Amylose (starch), Amylopectin (starch), Glycogen, Cellulose
- Hydrolysing agent Dilute acid, heated, Amylase, Maltase, Sucrase, Lactase, Cellulase
- Fatty acid 1 Lauric acid (12:0), Palmitic acid (16:0), Stearic acid (18:0), Oleic acid (18:1 cis), Elaidic acid (18:1 trans), Linoleic acid (18:2), α-Linolenic acid (18:3)
- Fatty acid 2 Lauric acid (12:0), Palmitic acid (16:0), Stearic acid (18:0), Oleic acid (18:1 cis), Elaidic acid (18:1 trans), Linoleic acid (18:2), α-Linolenic acid (18:3)
- Fatty acid 3 (triglyceride) Lauric acid (12:0), Palmitic acid (16:0), Stearic acid (18:0), Oleic acid (18:1 cis), Elaidic acid (18:1 trans), Linoleic acid (18:2), α-Linolenic acid (18:3)
- Type of lipid Triglyceride (fat, oil), Phospholipid (phosphatidylcholine)
- Show carbon numbers
Questions to explore
- Starch and cellulose are both made of glucose, so why can humans digest starch but not cellulose?
- How does the heavier branching of glycogen compared with amylopectin help an animal?
- Why are fats rich in cis-unsaturated fatty acids liquid at room temperature while saturated fats are solid?
