BY: RAHUL AND COLBY

Define terms: Gene, Allele, and Genome Gene: a heritable factor that controls a specific characteristic. Allele: one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of the gene. Genome: the whole of the genetic information of an organism.

Gene Mutation-Visual Representation

So, What is Gene Mutation? According to the IB syllabus statement 4.1.3, a gene mutation is a change to the base sequence of a gene. Gene mutations occur in two ways: they can be inherited from a parent or acquired during a person’s lifetime. Mutations that occur only in an egg or sperm cell, or those that occur just after fertilization, are called new (de novo) mutations.

Now that you know what Gene Mutation is, lets look at Genetic Disorders

What are Genetic Disorders? A genetic disorder or gene mutation disorder is a disease that is caused by an abnormality in a person’s DNA. Some mutations happen during cell division, when DNA gets duplicated, and others can occur when DNA is damaged from environmental factors such as UV radiation, chemicals or viruses. Most of the mutations that we hear about are the ones that cause diseases. Most inherited genetic diseases are recessive, so both of your parents must carry it to have an effect.

Example of a Gene Mutation Duchenne Muscular disorder, mutation D, chromosome Xp. Duchenne muscular dystrophy (DMD) is a recessive X-linked form of muscular dystophy, affecting around 1 in 3,600 boys, which results in muscle degeneration and eventual death.

Now let’s look at specific types of mutations!

Point Mutation Point mutation, change within a gene in which one base pair in the DNA sequence is altered. There are two types of point mutations: transition mutations and transversion mutations. Transition mutations occur when a pyrimidine base In contrast, transversion mutations occur when a purine base substitutes for a pyrimidine base

Silent/Missense/Nonsense Mutations Silent mutations result in a new codon (a triplet nucleotide sequence in RNA) that codes for the same amino acid as the wild type codon in that position. Missense mutations involve substitutions that result in functionally different amino acids; these can lead to alteration or loss of protein function Nonsense mutations, which are a severe type of base substitution, result in a stop codon in a position where there was not one before

Frameshift Mutation Frameshift mutations can lead to drastic loss of function and occur through the addition or deletion of one or more DNA bases. In a protein-coding gene the sequence of codons starting with AUG (where U is the RNA base uracil, which replaces T during transcription) and ending with a termination codon is called the reading frame.

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