Transcript Mutations - Lakeland Regional High School / Overview

Mutations
A change in the DNA
sequence that affects
genetic information
Germ cell mutations
• Occurs in gametes
• Do NOT affect the organism
but are passed on to
offspring
Somatic Cell Mutations
• Occurs in body cells
• Affects the individual
Types of Mutations
• A. Chromosomal Mutations
–Occurs during cell division
Deletion
• Loss of all or part of a
chromosome
–Opposite of duplication
(segment is repeated
Inversion
• Part of a chromosome
becomes oriented in reverse
of its usual direction
• Ex. TAGTAGTAG-•TAGTAGGAT
Translocation
• Part of one chromosome
breaks off & attaches to
another, nonhomologous
chromosome
Nondisjunction
• When a pair of homologous
chromosomes fail to
separate during meiosis
• Ex. Trisomy 21 – Down
Syndrome
B. Gene Mutations
• Results in different
proteins being made
Point Mutation
• Involves one nucleotide in
DNA sequence being
substituted
• Ex. TAG --- TCG
Frameshift Mutation
• One nucleotide is deleted
or inserted, the code is
shifted
• Ex. TAGTAG --- TAGAG
•
TAGTAG --- TAGTAAG
Causes of Mutations
• Mutagens- environmental
factors which damage
DNA
• A. Chemicals
• B. Electromagnetic
Radiation (X-rays)
• C. UV Light