3.31 Evolution

describe the process of evolution by means of natural selection.
-evolution: change in the form of organisms. (new form of organisms arising)
                : change in frequency (how many) of alleles.
-natural selection: the mechanism of evolution (first proposed by Charles Darwin)
-SA (Staphlococcus aureus) causes skin infection and also lung infection

evolving SA

first graph

-normal form is susceptible to methicillin (antibiotic) (antibiotic can kill SA)

-MSSA (methicillin susceptible SA)

second graph

-random mutation in SA allow breaking down of methicillin. 

-because it can break down it can no longer killed by the antibiotic (resistant form)

-MSRA (red on graph)

-2 forms of bacteria (called evolution) [MSSA, MSRA]

-when antibiotic are applied to the population MSSA is decreased and MRSA is becoming increasing common

-evolution: increase in frequency of allele (or resistance) 

2 features

-random mutation produces MRSA form

-the non random selection (due to antibiotics) selects MRSA to survive and MSSA to be selected and killed.

-natural selection is a process not a list.