3.31) Evolution

Describe the process of evolution by means of natural selection

Evolution

- change in form of organisms (new forms arising)

- change in frequency (how many) of alleles

Natural Selection 

- the mechanism of evolution (first proposed by Charles Darwin)

Example:

a bacteria staphlococcus aureus which can lead to skin and lung infection

The original form of such bacteria is sustained to be kill by methecilline, which is a type of antibiotic. (They are susceptible to the antibiotic.) MSSA

What happened is that a random mutation to the genome of the bacteria allowed us a characteristic of 'breaking down methecilline.' This means that it is no longer killed by the antibiotic. This new form is called the Resistant form, MRSA.

[Refer to definition number 1 of evolution]

Because the MRSA is resistant to the antibiotic, they became increasingly common (increase in frequency of the allele) 

[Refer to definition number 2 of evolution]

Two features of natural selection (process):

1. Random mutation - produce MRSA form 

2. Non-random selection - due to anti-biotic which is selecting the MRSA to survive and MSSA to be selected and killed