mutations

• A mutation is the change in the arrangement of bases in a gene. It could be a change in structure of chromosomes. 
• Mutations produce a new/superior protein which results in a gain of reproductive advantages. 
• A neutral mutation results in no change.
• The production of inferior or no protein results in fatal or disease causing proteins. 
• Mutations can arise spontaneously during DNA replication and can include base deletion and base substitution. They can occur in gametes and somatic cells. Faulty DNA can be repaired by specific enzymes, but any unrepaired mutations will affect the new proteins being made. 
• Mutations can be caused by mutagens/mutagenic agents can increase the rate of gene mutation. Ionising radiation like X-rays, gamma rays and nuclear radiation. UV rays and chemicals like bromine and benzene can also cause mutations. 
• Changes to an individual gene due to miscopying of one or more nucleotides. 
• Deletion or insertion of a nucleotide results in a frameshift. Frameshifts change the codon sequence and therefore the amino acid sequence. 
• Substitution mutations result in a change of one base. 
• Due to the degenerate nature of the genetic code, not all base substitutions cause a change in the sequence of amino acids. A deletion or insertion will cause a frame shift of all triplet codes downstream. 
• A change in base sequence of genes means different codons and therefore different amino acids coded for. This leads to a change in the primary structure of the protein which in turn causes a change in the secondary structure, the tertiary structure and the quaternary structure, this makes the protein a different shape. 
• A mutation may form a dysfunctional protein which means it cant work properly because it’s the wrong shape. 
• An entire chromosome is lost or repeated during cell division, this can occur spontaneously by a process called chromosome non-disjunction which can occur during meiosis.