Recalling elementary school, your teacher likely led holiday crafting.\u00a0 For example, she might have handed out pages with snowmen traced on them for the kids to cut out and decorate.\u00a0 Likely, the finished snowmen were affixed to the window or wall.<\/p>\n
Back then, photocopying was still pretty new; not all schools had a photocopier.\u00a0 If they did, they didn’t use them much; likely, photocopies were expensive.\u00a0 They still are, by the way:\u00a0 going “over-budget” on photocopies can be a real problem in bureaucracies.<\/p>\n
Therefore, the teacher didn’t use a photocopier.\u00a0 She traced each snowman by hand.\u00a0 However, she didn’t do it free-hand; she used a pattern.\u00a0 Likely, she drew one “good one” by hand on cardboard, then cut it out.\u00a0 To produce a snowman sheet for a child, she laid the cardboard pattern on a sheet of blank paper and traced around.\u00a0 Tracing around the cardboard was quick: likely, she could produce twenty-five snowmen sheets just as quickly that way as by going down the hall to the photocopier, running them off there, then bringing them back.\u00a0 What’s more, she could afterwards put the cardboard pattern away amongst her other supplies.\u00a0 Next year, it would be there, waiting to be put to use again.\u00a0 From one careful snowman drawing done on cardboard in her early days, she could produce unlimited snowman sheets over her teaching career.<\/p>\n
Let’s consider a cell in the human body.\u00a0 Like the teacher, it needs to repeat the same job(s).\u00a0 To a cell, a job is a chemical reaction.<\/p>\n
Does the cell do the reaction “free-hand”?\u00a0 No.\u00a0 Like the teacher, it makes a physical pattern that can be reused as many times as needed.\u00a0 That pattern, to a cell, is an enzyme.<\/p>\n
Most enzymes are proteins.\u00a0 Like the teacher’s snowman pattern, the enzyme’s shape defines which job it helps with.\u00a0 To the teacher, a different art project would require a different cardboard pattern.\u00a0 To the cell, each specific reaction requires its own specific enzyme.<\/p>\n
If the teacher could not use patterns, preparing for the art project might take prohibitively long; similarly, the cell’s life processes can not occur quickly enough without enzymes.\u00a0 Some poisons specifically target enzymes and shut them down.<\/p>\n
The veteran teacher found her job easy, since she’d accumulated such a helpful toolkit over her years.\u00a0 Similarly, a cell whose enzymes are all available and functional is likely very prosperous:)<\/p>\n