Mutations are errors made in the DNA sequence than can have negative side effects, no effect, or positive effects for an organism
Can We Help with Your Assignment?
Let us do your homework! Professional writers in all subject areas are available and will meet your assignment deadline. Free proofreading and copy-editing included.
Point Mutations
Mutations that occur at a certain point in the DNA
Substitution – the replacement of one base in a DNA sequence by another base
"Be Bold" No-Essay $10,000 Scholarship
The $10,000 “Be Bold” Scholarship is a no-essay scholarship that will be awarded to the applicant with the boldest profile. To us, boldest does not mean “best”, or “most accomplished”. Being bold means being: Earnest, Determined, Moving. The scholarship will be awarded to the student whose profile is most bold, according to these characteristics.
Deletion – the elimination of a base pair or group of base pairs from a DNA sequence
Insertion – the placement of an extra nucleotide in a DNA sequence
Substitution Errors:
Silent mutations:
– a mutation that does not result in a change in the amino acid coded for and, therefore, has no effect on the operation of the organism
– could be an error in an intron or in the 3rd base pair of a codon
Missense mutations:
– a change that leads to a different amino acid being placed in the protein sequence
– will cause a change in protein conformation (shape) à may be bad or may have no affect
Nonsense mutations:
– a change that causes a stop codon to replace a codon for an amino acid
– translation stops prematurely -> produces nonfunctional proteins ->often lethal
Insertion/Deletion Errors:
Frameshift mutations:
– caused by the insertion or deletion of one or two nucleotides in the DNA sequence
– drastic errors; can result in many different amino acids substituted or a stop codon read normal amino acid sequence:
Chromosomal Errors
A translocation is the transfer and exchange of a fragment of DNA between two nonhomologous chromosomes
– if they happen to fall within a coding region of a gene, they will disrupt the correct transcription of the gene
An inversion is a chromosomal segment that has reversed it’s orientation in the chromosome causing the gene to be disrupted
Causes of Genetic Mutations
Spontaneous mutations – mutations caused by errors in DNA replication or crossing over in meiosis
Induced mutations – mutations caused by mutagenic agents like UV radiation, cosmic rays, X rays, and certain chemicals
