Mutations are changes in DNA sequence that can be caused by mistakes during cell division or exposure to environmental agents. Mutations can be harmful, beneficial, or have no effect depending on where they occur. Germline mutations occur in gametes and can be inherited, while somatic mutations occur in other cells and are not inherited. Different types of mutations include point mutations, which change a single nucleotide, and frameshift mutations, which change the reading frame by inserting or deleting nucleotides.

1. Mutation
introduction
Any change in the DNA sequence of a cell. Mutations may be
caused by mistakes during cell division, or they may be caused
by exposure to DNA-damaging agents in the environment.
Mutations can be harmful, beneficial, or have no effect. If they
occur in cells that make eggs or sperm, they can be inherited; if
mutations occur in other types of cells, they are not inherited.
Certain mutations may lead to cancer or other diseases. A
mutation is sometimes called a variant.

2. types of mutation
Germline mutations occur in gametes. These mutations are
especially significant because they can be transmitted to
offspring and every cell in the offspring will have the mutation.
Somatic mutations occur in other cells of the body. These
mutations may have little effect on the organism because they
are confined to just one cell and its daughter cells. Somatic
mutations cannot be passed on to offspring. A point mutation is a
change in a single nucleotide in DNA. This type of mutation is
usually less serious than a chromosomal alteration. An
example of a point mutation is a mutation that changes the codon
UUU to the codon UCU. frameshift mutation is a deletion or
insertion of one or more nucleotides that changes the reading
frame of the base sequence.

3. MUTAGEN
A mutagen is a chemical or physical
agent capable of inducing changes in
DNA called mutations. Examples of
mutagens include tobacco products,
radioactive substances, x-rays,
ultraviolet radiation and a wide variety
of chemicals

4. Photoreactivation
Photoreactivation is a light-induced (300-600 nm)
enzymatic cleavage of a thymine dimer to yield two
thymine monomers. It is accomplished by
photolyase, an enzyme that acts on dimers
contained in single- and double-stranded DNA .

5. SOS response
The SOS response is a worldwide gene regulation mechanism
that bacteria such as Escherichia coli employ to respond to
treatments that damage DNA...
Gene Name: Protien encoded/roel in DNA repair Pol B (din
A): Encoded polymerisation subunit of DNA polymerase II,
required for rep... RecA: Encodes RecA protien rwequired for
error-prone repair and recombinational

6. Nucleotide excision repair (NER)
Nucleotide excision repair (NER) is the main
pathway used by mammals to remove bulky DNA
lesions such as those formed by UV light,
environmental mutagens, and some cancer
chemotherapeutic adducts from DNA.
Nucleotide excision repair (NER) is a particularly
important excision mechanism that removes DNA
damage induced by ultraviolet light (UV). UV DNA
damage results

7. DNA repair
DNA repair, any of several mechanisms by which a
cell maintains the integrity of its genetic code. DNA
repair ensures the survival of a species by enabling
parental DNA to be inherited as faithfully as
possible by offspring. It also preserves the health of
an individual
MADE BY – Kirtika Chauhan