genetic mutations

Gene Mutations

A mutation is a change in the genetic material of an organism

when / where doecan mutations occurs ?

Mutations can occur spontaneously during DNA replication, or through contact with mutagenic elements such as:

•   Tar from tobacco smoke

•   UV light

•   X-rays

•   Gamma rays

does error occurs ?

yes , the double helix structure of DNA makes it fairly resilient and resistant to corruption or damage. However, errors do occur.

Errors that occur in mitosis are somatic mutations and do not get passed to offspring. They can however cause disease (such as cancer).

what are the two main classes of DNA mutation ?

•   Point mutations

• Indel mutations

what is a codon ?

a sequence of three nucleotides (bases) in DNA or messenger RNA (mRNA) that acts as a specific instruction, telling the cell which amino acid to add to a growing protein chain or signalling the end of protein synthesis (a stop codon). These triplets form the basis of the genetic code, translating the four-letter nucleic acid alphabet (A, U/T, C, G) into the 20- amino acids.

Point mutations

Point mutations are where one nucleotide base is swapped for another by mistake.

what are three main types of point mutation ?

•   Silent

•   Missense

•   Nonsense

Silent Mutations

A point mutation is where a nucleotide base is changed. A silent point mutation is where the mutation results in no change to the amino acid coded for. As such, there is no consequence to the mutated base.

Missense Mutations

A change in the base sequence that results in the change to amino acid structure is known as a missense mutation. This change can have significant effect on the protein produced as a result and can leave it faulty or nonfunctional.

Nonsense Mutations

Sometimes a mutation can result in a stop codon being produced prematurely. This can severely truncate the amino acid sequence and therefore cause a protein that will not function within the cell.