The Gene Pool

Causes of changing allele frequencies in a population's gene pool, including environmental selection pressures, genetic drift and mutations as the source of new alleles

Gene pool

Total aggregation of all genes and alleles present within a particular population or species.

Allele frequencies

The proportion a particular allele appearing at a certain gene locus in a gene pool

Allele

An alternate form of a gene

Mutations

Involves permanent changes to the DNA sequence of an individual that can occur spontaneously or be induced by agents known as mutagens (e.g. UV radiation). For a mutation to be passed down to offspring, it must occur in an individual germline cells.

Silent mutation

Silent mutation are point mutation which changes a single nucleotide but does not change the resulting amino acid sequence (protein). This is due to the degenerate nature of the genetic code where multiple different codons code for the same amino acid, therefore, despite a change to the original DNA sequence. the same amino acid is incoporated into the protein.

Missence mutation

Missense mutation are point mutation that changes a single nucleotide in the gene sequence which code for a different amino acid, altering the primary structure of the polypeptide. This in turns affects the folding of the polypeptide and could alter the functioning of the protein.

Nonsense mutations

Are point mutation that changes a single nucleotide that result in a stop codon prematurely end the translation of a gene’s mRNA, resulting in a shorter polypeptide chain which is likely to be non functional.

Frameshift mutation

Addition or deleteion of one of nucleotide which alters the reading frame of all the following nulceotide. The reading frame is how DNA or mRNA is divdided or condons respectively. Since the reading frame is shifted in frame shift mutation, all following codons and the amino acid they code for are effected which can cause chages to the structure and function of the proteins.

Block mutations

Changes to larger section of DNA, potentially causing significant changes to the DNA sequence of an organism. This involves the alteration of the structure of a chromosome by deleting, duplicating, inverting or translocating a cluster of nucleotides which may involve multiple genes.

Duplication (block mutation)

A genetic mutation in which a region that contains a gene or an entire chromosome is repeated, which results in multiple copies of that region or nucleotide.

Inversion (block mutation)

A genetic mutation in which part of a chromosome breaks off, rotates 180° and rejoins chromosome

Deletion (block mutation)

Part of the chromosome is lost

Insertion (block mutation)

A section of DNA is added to a chromosome

Aneuploidy

Chromosomal abnormality in which an organism possesses an incorrect number of chromosomes caused by the addition or loss of an individual chromosome

Polyploidy

A choromsomal abnoramility in which an oranism has incorrect number of sets of each chromosome