Mutations
Now we
present an article of mutations but to talk about mutations we first need to
understand what is a mutation?
Mutations occur in the DNA that is the hereditary material that all beings
living have, if there is a change in the genetic code that the DNA has, a
mutation will occur that has consequences for the individual. In the DNA are
the codes that will define how the organism will be in every aspect.
Mutations can be good, bad or neutral for the organism. Most mutations are
random because they do not give the individual what he needs. Many experts say
that mutations are related to the aging of cells.
Once clear that they are the mutations these can be divided into two large
groups that are somatic mutations and germline mutations.
Somatic mutation: The somatic mutation is the one originated by mitosis, that is, reproduction in cells that make up tissues.
From the mutated cell, more clones like it are created by cell division. An
example is cancer in which some genes called protooncogenes mutate and the
cells begin an uncontrolled division, as they divide they come together forming
a tumor.
Germline mutations: these types of mutations occur in gametes, but this
mutation is hereditary. An individual can have mutations in their germ line and
will only realize in their offspring, unlike the somatic mutation this type of
mutations do not affect the organism that has the gametes but the baby that was
fertilized.
MUTATION CLASIFICATION.
Mutations are
classified into three groups that are gene or point, chromosomal and genomic.
Gene mutations
are those that alter the nucleotide sequence of a single gene, that is because
instead of one thymine nucleotide one cytosine goes; also by the loss of
nucleotides and the insertion of these or that there are more pairs of
complementary nucleotides.
Another type of
mutations are the chromosomes: the structures of the chromosomes are modified
but not their number. The change occurs in the nucleotide sequence in the DNA
that is then transcribed in the messenger RNA, causing affected genes.
Mutations in
genes are divided into two groups. the group where the order of genes is
affected (inversions and translocations) and the group where affects the number
of genes (duplications and deletions).
Investments: is
that a chromosome fragment has rotated 180 ° so the genetic sequence is
inverted. When the centromere is affected and there is a change in the shape of
the chromosome it is called pericentric inversion but when none of this happens
it is called a paracentric inversion.
Translocations:
is the change of position of a fragment of the chromosome, there are two types
of translocation that are the reciprocal in which fragments are exchanged and
transposition where this does not happen.
Duplication:
occurs when a chromosome fragment is repeated on the same or another
chromosome.
Deletion: it is
produced by the loss of a chromosomal fragment and also by the loss of the
genes that do not contain it
The genomic
mutation is the change of the normal number of chromosomes that should have the
individual, is given by an unequal distribution in the meiosis of the formation
of gametes. This type of mutation can be divided into two which are euploidias
and aneuploidies.
Euploidias:
consists of changing the number of complete sets of chromosomes with respect to
the normal number of the species, if within the sets of chromosomes there is an
increase in number, that is, they are tripods or tetraploids, it is called
polyploid. If on the contrary there is a single game (n) it is called haploid
or monoploidy.
Aneuploidia: are
the mutations that affect only the number of chromosomes of a couple.
Aneuploidy occurs due to lack or excess of chromosomes an example in humans is
the Down´s syndrome.
