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Genetic diversity, meiosis and adaptations GapFill

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 MutationsSegregationsReversalsMitosions are changes to the genetic material of an individual, which may occur spontaneously due to a fault in DNA replication. If the wrong base is incorporated into a sequence it is known as a  base miscalculationbase replicationbase substitutionbase shift; however, because many amino acids are coded for by more than one triplet, this does not always result in a change in the final amino acid sequence. If a base deletion occurs, it usually has a more profound effect on the resulting polypeptide due to the introduction of a  histoneframe shifthaploid cellnew allele.

 MagnificationMeiosisMitosisPolymerisation is another method which can increase genetic diversity. Independent segregation of  introns and exonsnucleotidestRNA and mRNA moleculeshomologous chromosomes means that daughter cells contain different combinations of maternal and paternal genes, and  facilitated diffusioncrossing overco-transversionswitching sides can also result in recombination of alleles to produce non-identical daughter cells.  Cross-contaminationNucleationCondensationRandom fertilisation of gametes then restores the correct number of chromosomes to a cell, while introducing further variation.

Natural selection relies on the generation of new alleles by these processes. If an allele provides a selective  symbiosisadvantagepressuregeneration in a certain environment, it is more likely to be passed on to the next generation and increase in  definitionfrequencyimportancestrength within a population. For example, a new allele for antibiotic resistance in bacteria is likely to spread throughout a population through the process of  resolutionultracentrifugationdirectional selectionmagnification. If natural selection favours the average phenotype and selects against extremes, e.g. in human birth weight, this is known as  stabilising selectionextremist selectiondisruptive selectionphenotypic selection.

Through natural selection, species become more adapted to their environments. This may be through:

  •  conservativeanatomicalbiologicalreproductive adaptations, such as thick fur to protect against cold climates
  •  structuralphysiologicalchemicaldestructive adaptations, such as the production of venom to aid in hunting
  •  mentalcharacteristicconsequentialbehavioural adaptations, such as basking in the sun to warm up in the morning

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