Ten people are sitting in a row. Their objective is to whisper a secret from one person to the next all the way down the row. The first person whispers the secret to the second person who passes the secret to the third person and so on. After whispering to the third person, the second person in the row notices the ninth person has fallen asleep in their chair, so she gets up, goes down the row and shakes person nine awake. This example is similar to . Ten people are sitting in a row. Their objective is to whisper a secret from one person to the next all the way down the row. The first person whispers the secret to the second person who passes the secret to the third person and so on. After whispering to the third person, the second person in the row notices the ninth person has fallen asleep in their chair, so she gets up, goes down the row and shakes person nine awake. This example is similar to . feed-forward activation allosteric control negative modulation positive cooperativity