DNA DNA MUTATIONSMUTATIONS

BYBY

SARA KANWAL SARA KANWAL

BS-MT 3BS-MT 3RDRD YEAR 6 YEAR 6THTH SEMESTERSEMESTER

CONTENTS:CONTENTS:

• DNADNA• DNA MUTATIONDNA MUTATION• TYPESTYPES• CLASSIFICATIONCLASSIFICATION

DNA: (deoxyribo nucleic DNA: (deoxyribo nucleic acid)acid)

DNA is a DOUBLE HELICAL structure consist of

DEOXYRIBOSE SUGAR and FOUR NITROGEN BASES.

Four bases :• Adenine• Guanine• Thiamine• cytosine

DNA MUTATIONSDNA MUTATIONS:

Mutation is a permanent change in the DNA.

• Mutations in germ cells are transmissible.

• Mutations in somatic cells are non-transmissible but may contribute to change( malignant transformation)

TYPES OF MUTATIONS:TYPES OF MUTATIONS:• POINT MUTATION:

1. Missense mutation.2. Silent mutation.3. Non-sense mutation.

• FRAME-SHIFT MUTATION:

1. Insertion2. Deletion3. inversion

POINT MUTATIONS:POINT MUTATIONS:

Point mutations are the single-based mutations. ( a change in

one nucleotide of the sequence)

CLASSIFICATION OF POINT CLASSIFICATION OF POINT MUTATIONMUTATION:

• Missence mutation

• Silent mutation

• Non-sense mutation

MISSENSE MUTATION:MISSENSE MUTATION:

• The new codon causes an incorrect AMINO ACID to be inserted into the protein.

• This effect on the function of the protein depend on what is inserted in place of normal amino acid.

NON-SENSE MUTATION:NON-SENSE MUTATION:

The new codon causes the protein to prematurely TERMINATE, producing a product that is

shortened and often does not function.

SILENT MUTATION:SILENT MUTATION:

Silent mutation does not causes any change

in amino acid.

(Silent mutation codes for same amino acid)

FRAME-SHIFT MUTATION:FRAME-SHIFT MUTATION:

Frame-shift mutation is a change in the reading frame of DNA.

• The loss or gain of 1 or 2 nucleotides causes the affected codon and all of the codons that follow to be misread.

• This leads to a very different and often non-functional protein product.

DELETIONDELETION:

• Mutations that result in MISSING DNA are called DELETIONS.

• Deletions can also cause frame-shift mutation

For example:For example:

• ORIGINAL: ORIGINAL:

The fat cat ate the wee rat

• DELETION:DELETION:

The fat ate the wee rat

INSERTIONS:INSERTIONS:

• Mutations that result in the addition of extra DNA are called insertions.

• Insertions can also cause frame shift mutations, and general result in a nonfunctional protein.

For example:For example:

• ORIGINAL:ORIGINAL:

The fat cat ate the wee rat

• INSERTION:INSERTION:

The fat cat xlv ate the wee rat

INVERSIONSINVERSIONS:• In an inversion mutation, an entire

section of DNA is reversed.

• inversions involve large regions of a chromosome containing several genes.

For example:For example:

• ORIGINAL:ORIGINAL:

The fat cat ate the wee rat

• INVERSION:INVERSION:

The fat tar eew eht eta tac