Mutations

Point Mutations

Topic Menu
Content Contributors
Christian Bien Portrait_edited.jpg

Ben Whitten

Learning Objectives

tutorial.png

one.png
What are point mutations?
Slide1.jpeg

Point mutations can be defined as the simplest form of mutation, where a single nucleotide within the original DNA sequence is affected by either; 


  • Substitutions 

  • Insertions and deletions

two.png
What are substitutions?
Slide2.jpeg

Image: Mackenzie Angell, Graphic Designer


Substitutions occur when one nucleotide is replaced by another nucleotide. Differences of a single nucleotide in a sequence are also called single nucleotide polymorphisms (SNPs), as when the codon in the sequence that codes for amino acids is altered, the mutation may have a subtle or dramatic effect on its structure and function. 


There are three subcategories of substitutions. 


1. Synonymous mutations (silent): These occur when the substituted base results in a codon that codes for the same amino acid as the original codon


2. Missense mutations: This arises when an SNP changes the amino acid. For example, a substitution of an AGA codon (arginine) to an AGC codon results in a serine amino acid being produced. 


3. Nonsense mutations: This arises when an SNP creates a new stop codon, leading to early termination of translation of the transcribed gene sequence.

two.png
What are insertions and deletions?
Slide2.jpeg

Image: Mackenzie Angell, Graphic Designer


An insertion mutation is the addition of either one or more nucleotides at a particular place in the original sequence. 


A deletion mutation is the loss of one or more nucleotides at a particular place in the original sequence. 


The effect of this type of mutation is called a frameshift effect, as the whole sequence has been moved. In other words, the reading frame for the amino acids has been moved slightly which has drastic effects on all the codons for the rest of the sequence.

two.png
Slide2.jpeg
two.png
Slide2.jpeg
two.png
Slide2.jpeg
two.png
Slide2.jpeg
two.png
Slide2.jpeg
Gene Pools and Mutations
Causes of Mutations
Chromosomal Mutations
Point Mutations
Effects of Mutations
Gene Mutation Conditions
Chromosomal Mutation Conditions
Lethal Recessives
Students Walking Up Stairs_edited.jpg

Registrations Now Open for Empowered Academy

A Free Student-Centred Revision Program

Logo-New-Large.png