Understanding Genetic Material and Mutations

Genetic Material

Genetic information is stored in the DNA molecule and is composed of three elements:

• Silica
• A sugar phosphate group
• A nitrogenous base

Chromosome

Hereditary information for each individual is stored in the DNA. This is called the genome, and the protein formed by it is called chromatin.

Genes

A gene is the unit of living legacy and consists of a linear sequence of nucleotides in the DNA molecule.

Homologous Chromosome

In somatic cells, each chromosome has a companion, which constitutes a pair of homologous chromosomes.

Mutation

A mutation is an alteration or change of genetic information in a living being. Therefore, it will produce a change of features spontaneously and can be transmitted or inherited by the offspring.

Genetic Mutation

A genetic mutation is an alteration in the sequence of nucleotides in a gene. It is divided into two types:

• Base pairs of lost or insertion of nucleotides

Base Pairs

Transitions

Transitions are the change of a nucleotide in the DNA sequence from one purine base to another or from one pyrimidine base to another.

Transversions

Transversions are the change of a purine base to a pyrimidine base or vice versa.

Nucleotides

This is divided into two types:

• Genetic additions: The insertion of nucleotides in the gene sequence.
• Genetic deletion: The loss of one nucleotide.

Structural Chromosomal Mutations

Structural change is internal to chromosomes. Chromosomes are grouped into two types:

• Deletion Chromosomes: The loss of a segment of a chromosome.
• Chromosomal Duplication: The repetition of a segment of a chromosome.

Investment

Investment occurs when a chromosome segment is located in an inverted position.

Translocations

Translocations occur when a chromosome segment is located on another homologous or non-homologous chromosome.

Chromosomal Mutation Numbers

These are changes in the number of chromosomes in a species.

Euploidy

Euploidy occurs when the mutation affects the full set number of chromosomes with respect to the normal number of chromosomes of the species.

Aneuploidy

Aneuploidy occurs when only one part of the chromosome set is involved. These may be given on autosomes, e.g., Down Syndrome.

Monosomy

Monosomy is when a chromosome is missing from a pair of counterparts.

Trisomy

Trisomy is when there are three chromosomes instead of the normal two.

Tetrasomy

Tetrasomy is when there are four chromosomes, pentasomy is when there are five, etc.