One family is defined by what water refuses to do with it. The other stores every instruction you will ever run. Both come down to hydrogen bonds — or the lack of them.
Lipids have one thing in common and it is a negative: no polar groups worth speaking of. Everything else — storage, membranes, insulation — follows from being excluded by water.
Glycerol plus three fatty acids, joined by ester bonds in a condensation reaction that releases three waters. Assembled, but not a repeating chain.
A cis double bond bends the tail. Bent tails cannot pack, so the fat melts lower and the membrane stays fluid.
Highly reduced C–H bonds mean roughly 38 kJ per gram against 17 for carbohydrate — and lipids store dry, without the water starch holds.
Tap each part. Watch how one substitution — a phosphate in place of a fatty acid — turns a storage molecule into a membrane.
Tap the phosphate head, glycerol, the ester bonds, either tail, or the bilayer inset.
Four membranes, one variable at a time. Watch the spacing between the tails — that spacing is the fluidity.
A nucleic acid is a chain of three-part monomers. Two of the three parts are identical all the way along — only the base changes, and that is where the information lives.
Phosphate, pentose sugar, nitrogenous base. Also the basis of ATP, NAD and FAD — the same subunit, different job.
Phosphodiester bonds run from carbon 5' to carbon 3', so a strand has a head and a tail. Sequences are always written 5' to 3'.
Purine to pyrimidine, held by hydrogen bonds: two for A–T, three for G–C. Weak enough to unzip, specific enough to copy.
Tap each part of the double helix, flattened out. The two pink arrows are the detail most students lose marks on.
Tap the backbone, a phosphodiester bond, an A–T pair, a G–C pair, the labelled ends, or the direction arrows.
Tap a node to light up its connections. The pink dashed link joins the two halves of this lesson.
Two families, one shared principle: water decides what goes where.
Drag a term into a gap, or tap a term and then tap a gap. Two terms belong nowhere.
Fatty acid tails are nonpolar and therefore , and each is joined to glycerol by an bond. A tail with no carbon–carbon double bonds is and packs tightly, whereas a kinked tail cannot — which raises membrane . In a nucleic acid, nucleotides are joined by bonds between carbon 5' of one sugar and carbon 3' of the next. The two strands of DNA run in opposite directions, so they are described as . Guanine pairs with cytosine using hydrogen bonds.
Single best answer. You get the reasoning as soon as you commit.