A certain signal molecule S in heart tissue is degraded by two different biochemical pathways: when only Path 1 is active, the half-life of S is 3.9 s. When only Path 2 is active, the half-life of S is 104. s. Calculate the half-life of S when both pathways are active.

Half life of S = 3.76secs

Explanation:

The concept of half life in radioactivity is applied. Half life is the time taken for a radioactive material to decay to half of its initial size.

For part 1 - How much signal will be degraded in 1secs = 1/3.9 = 0.2564

for part 2 - How much signal will be degraded in 1secs = 1/104 = 0.009615

Simply say = 1/3.9 + 1/104 = 0.266015

So both part 1 and part 2 took 1/0.266015 = 3.76secs is the half life of S when both pathways are active