Chromosomes carry hereditary information and mutations can occur through problems during cell division or exposure to mutagens. There are several types of chromosomal mutations that can change the structure or number of chromosomes including translocations, deletions, duplications, inversions, and isochromosomes. These mutations can result in aneuploidy, having an abnormal number of chromosomes through trisomy, monosomy, or polyploidy of having multiple sets of chromosomes. Chromosomal mutations can cause developmental issues and health problems depending on the type of structural change or chromosomal material lost or gained.

1. CHROMOSOMAL
MUTATION

2. What are chromosomes?
Chromosomes are long, stringy aggregates of
genes that carry heredity information (DNA).
Chromosomes are located in the nucleus of our
cells and condense prior to the process of cell
division.
A chromosome mutation is an
unpredictable change that occurs in a chromosome.

3. These changes are most often brought on by
problems that occur during meiosis (division process of
gametes) or by mutagens (chemicals, radiation, etc.).
Chromosome mutations can result in changes in the
number of chromosomes in a cell or changes in the
structure of a chromosome. Chromosome mutations
change and impact the entire chromosome.

4. What Causes Chromosomal Mutation?
Chromosomal mutation that alters chromosome
structure. These changes affect protein production by
changing the genes on the chromosome. Chromosome
structure changes are often harmful to an individual
leading to developmental difficulties and even death.

5. There are several types of chromosome structure
changes that can occur. Some of them include:
a. Translocation
Translocation means a change in location.The joining
of a fragmented chromosome to a non-homologous
chromosome. The piece of chromosome detaches from
one chromosome and moves to a new position on
another chromosome.

7. b. Deletion
This mutation results from the breakage of a
chromosome in which the genetic material becomes
lost during cell division. The genetic material can break
off from anywhere on the chromosome.
Deletion can involve the loss of any number of
nucleotides, from a single nucleotide to an entire piece
of a chromosome.

9. c. Duplication
Duplications are produced when extra copies of
genes are generated on a chromosome.
A type of mutation in which one or more copies
of a DNA segment (which can be as small as a few
bases or as large as a major chromosomal region) is
produced.

12. d. Inversion
An inversion in a chromosome occurs when a
segment breaks off and reattaches within the same
chromosome, but in reverse orientation. DNA may or
may not be lost in the process.
If the inversion encompasses the centromere of the
chromosome, it is called a pericentric inversion. If it
involves the long or short arm of the chromosome and
does not include the centromere, it is called a
paracentric inversion

13. Pericentric inversions can lead to
changes in the size of a chromosome's
arms.
The long arm is referred to as the q
arm. The shorter arm is referred to as
the p arm. If this chromosome were to
undergo a pericentric inversion, where
most of the region inverted came from
the q arm and only a small portion
came from the p arm, then there would
be a change in the relative sizes of the
arms.

14. e. Isochromosome
This type of chromosome is produced by the
improper division of the centromere.
Isochromosomes contain either two short arms or
two long arms. A typical chromosome contains one
short arm and one long arm.

17. Types of Chomosomal
Mutation

18. Aneuploidy - A chromosome mutation that causes
individuals to have an abnormal number of
chromosomes
Aneuploid cells occur as a result of chromosome
breakage or nondisjunction errors that happen during
meiosis or mitosis
Nondisjunction is the failure of homologous
chromosomes to separate properly during cell division.
It produces individuals with either extra or missing
chromosomes.

19. There are two main types of aneuploidy;
1. trisomy -there can be an extra copy of a
chromosome
2. Monosomy- a missing copy of a chromosome
A Turner syndrome diagnosis, or monosomy X,
occurs when your baby only has one X sex
chromosome instead of a pair.

20. Examples of Trisomy
Down syndrome: An extra copy of chromosome
21.
Trisomy 18: An extra copy of chromosome 18 that
used to be called Edwards syndrome.
Trisomy 13: An extra copy of chromosome 13 that
used to be called Patau syndrome.

21. Polyploidy
Polyploidy describes the case of a cell or an individual
possessing entire extra sets of chromosomes.
A chromosome mutation that results in individuals with
more than one haploid set of chromosomes in a cell
A haploid cell is a cell that contains one complete
set of chromosomes. Our sex cells are considered haploid and
contain 1 complete set of 23 chromosomes.

22. Our autosomal cells are diploid and contain 2
complete sets of 23 chromosomes. If a mutation
causes a cell to have three haploid sets, it is
called triploidy. If the cell has four haploid sets, it
is called tetraploidy.