University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

414

Pages:

2
Author:

Mariam A. A.

Mutations. ✓ Mutation alters the allele’s identity because the DNA sequence is altered. This new DNA sequence can lead to an alternative expression of the gene. ✓ In most cases, mutation only involves the modification of a DNA nucleotide, changing its nitrogenous base (point mutation). ✓ In some more extreme cases, it can modify the DNA sequence of a portion of chromosome that involves one or more genes (chromosomal mutation). ✓ Altering the nucleotide sequence of a gene will result in the specification of a different protein OR may modify the structure and function of the protein such that it will no longer functions as efficiently or completely not functional at all. ✓ For example, mutation completely alters the identity of this allele originally coded for blue eye colour. This means that it may code for something slightly or completely different instead. Perhaps maybe, green eye colour. ✓ Since alleles are altered, this would mean that through mechanisms of sexual reproduction and fertilisation, mutated allele will be inherited by gamete and possible give rise to offspring when fertilised. This would mean that a new allele will be introduced into the population. This would mean that there would be an increase in genetic variation in the population as allele frequency will increase. ✓ Note that mutation on genes in autosomes and sex chromosomes will be passed onto offspring if ONLY the mutation occurs in the parents’ germ cell. The gametes derived from the parent germ cell (gamete/sex cell) then becomes an offspring when gamete is fertilised where the offspring can inherit the mutation. Most mutations passed onto offspring may not expressed as they could be recessive, so offspring needs to inherit one mutated allele from each parent in order to express the mutated characteristic. ✓ Recessive traits only appear if both alleles are recessive. (both small cases, e.g. rr) ✓ Mutations are permanent changes to an organism’s DNA sequence. ✓ Mutation is considered the principal and original source in creating genetic variation in a population. This is because they provide the creation of new alleles by altering DNA sequence. The parent can be copying such mutated DNA via meiosis I which gametes and, when fertilised, the offspring can inherit such mutated DNA. ✓ Not all of the four gametes must inherit such mutated DNA though. ✓ Anyways, similar to crossing over, independent assortment, random segregation, we should now know that mutation also creates genetic variation in a population which provides a pathway for evolution to occur. ✓ Without genetic variation, there will be no mechanisms for evolution. ✓ As genetic variability in a population increases, the species’ population ability to adapt to its environment over time also increases. It is through such adaptability of species in a population overtime, which creates apprent evolution due to shifts in dominant or new characteristics in the species’ population.