This document discusses mutation and microevolution. It defines mutation as an inheritable change in DNA that creates a new gene allele. Mutation is a primary mechanism of microevolution and can affect genetic equilibrium by creating new alleles that may become advantageous and increase in a population over generations. The document also describes the mutation pressure theory, which proposes that the effects of mutation on a genome are not random but push the guanine and cytosine content of DNA in a higher or lower direction, generating directional changes more in neutral parts of the genome.

1. By the nameof Allahthe most Beneficent
And most Merciful
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2. Content
A. Introduction
B. Definition
C. Primary mechanism of microevolution
D. Mutation effect genetic equilibrium
E. Mutation pressure theory
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3. A. Introduction
A mutation is an inheritable change of
gene by one of several different
mechanisms that alter DNA sequencing of
an existing allele to create a new allele for
that gene.
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4. B. Definition
It is change in allele frequencies due
to repeated occurrence of same mutation.
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5. C. Primarymechanismof microevolution
 a primary mechanism of microevolution is
formation of new alleles by mutation.
 spontaneous errors in replication of DNA create
new alleles instantly while physical and chemical
mutagens create mutations constantly at lower rate.
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6. D. Mutationeffectgenetic equilibrium
 by altering the DNA ,thus creating new alleles ,they may
then become part of reproductive gene pool for population.
 when a new allele create an advantage for offspring , the
number of individuals with new allele may increase
dramatically through successive generation.
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7. E. Mutationpressuretheory
PROPOSITION:
A quantitative theory of directional mutation pressure proposed in
1962.
WHAT IT EXPLAIN??
It explained the wide variation of DNA base composition observed
among different bacteria and its small heterogeneity within individual
bacterial species.
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8. BASE OF THEORY:
 Based on assumption that effect of mutation of genome is
not random but has direction towards higher or lower
“Guanine” plus “Cytosine” content of DNA.
 This pressure generates directional changes more in neutral
parts of genome than in functionally significant parts.
 Now that DNA sequence data are available ,the theory
allows the estimation of extent of neutrality of directional
mutation pressure against selection.
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