1 For example, the disorder sickle cell anaemia is caused by a mutation in the gene that instructs the building of a protein called haemoglobin. 2  This causes the red blood cells to become an abnormal, rigid, sickle shape. 3  However, in African populations, having this mutation also protects against malaria.
Optimistic time - generally the shortest time in which the activity can be completed. It is common practice to specify optimistic times to be three standard deviations from the mean so that there is approximately a 1% chance that the activity will be completed within the optimistic time.
a short interval between the acts of a play or parts of a public performance, usually a period of approximately 10 or 15 minutes, allowing the performers and audience a rest. a period during which action temporarily ceases; an interval between periods of action or activity: They studied for hours without an intermission.