Mutations 3.29 Recall that mutation is a rare, random change in genetic material that can be...
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Transcript of Mutations 3.29 Recall that mutation is a rare, random change in genetic material that can be...
Mutations
• 3.29 Recall that mutation is a rare, random change in genetic material that can be inherited.
• 3.31 Understand that many mutations are harmful but
some are neutral and a few are beneficial. • 3.33 Understand that the incidence of mutations can
be increases by exposure to ionizing radiation (e.g. gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (e.g. chemicals in tobacco).
3.29 Recall that mutation is a rare, random change in genetic material that can be inherited.
• A mutation is a change in the DNA of a cell.• It can happen in individual genes or in whole
chromosomes. • Sometimes, when DNA is replicating, mistakes
are made and the wrong nucleotide is used. • This results in a gene mutation and it can alter
the sequence of the bases in a gene.• This then can lead to the gene coding for the
wrong protein.
There are several ways in which gene mutations can occur:
• Duplication of a nucleotide– Nucleotide inserted twice
• Deletion of a nucleotide– A nucleotide is missed out
• Substitution of a nucleotide– A different nucleotide is used
• Inversion of a triplet– The sequence of the bases in a triplet is reversed.
3.31 Understand that many mutations are harmful but some are neutral and a few are beneficial.
• Sometimes a gene mutation can be advantageous to an individual.
• This can be due to a random mutation.• For example: a bacteria can become resistant
to antibiotics.•
3.33 Understand that the incidence of mutations can be increases by exposure to ionizing radiation (e.g. gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (e.g. chemicals in tobacco).
• Gene mutations are random events that occur is all organisms.
• The rate at which they occur can be increased by a number of agents called mutagens.
• Mutagens include:– Ionising radiation (UV light, X-rays and gamma rays)– Some chemicals
• Mustard gas• Nitrous oxide• Cigarette smoke and tar• Some chemicals from burnt food