This document discusses different types of mutations including gene mutations and chromosomal mutations. It describes point mutations such as single base substitutions, insertions, and deletions as well as frameshift mutations that can occur from insertions or deletions. It also discusses chromosomal mutations like duplications, inversions, translocations, and deletions. Non-disjunction during meiosis can result in aneuploidy with an extra or missing chromosome. Mutations can be harmful and cause genetic disorders or cancer, but some are beneficial and lead to evolution or traits in polyploid plants. Examples of genetic disorders and polyploid crops are also provided.

1. 12-4 Mutations

2. 12-4 Mutations
• Changes in the genetic material
• Kinds of mutation
– Gene mutation
• Changes in a single gene
– Chromosomal mutation
• Changes in whole chromosome

3. Gene mutation

4. Gene mutation
• Types
– Point mutation: changes in one nucleotide
• Single base substitution
• Single base insertion
• Single base deletion
– Frame shift mutation: changes in nucleotides leads to the
shift of reading frame (grouping of the codons)
• Insertion
• Deletion

5. Normal gene Substitution GGTCACCTCACGCCA
GGTCTCCTCACGCCA ↓
↓ CCAGUGGAGUGCGGU
CCAGAGGAGUGCGGU mRNA codons
mRNA codons ↓
↓ Pro-Arg-Glu-Cys-Gly
Pro-Glu-Glu-Cys-Gly Amino acids
Amino acids
Deletion Insertion GGTGCTCCTCACGCCA
GGTCCCTCACGCCA ↓
↓ CCACGAGGAGUGCGGU
CCAGGGAGUGCGGU ↓
↓ Pro-Arg-Gly-Val-Arg
Pro-Gly-Ser-Ala-Val

7. Chromosomal mutation
1.duplication
Structure 2.inversion
change 3.translocation
4.deletion
Changes in
Have one extra or one
chromosomes aneuploidy less chromosome
(2n+1,2n-1)
Number Caused by
change nondisjunction
polyploidy Have three or more sets
of each type of
chromosome (3n, 4n)

9. Non-disjunction
• Fails to separate chromosomes in meiosis 1 or 2
• Gametes become n-1 or n+1
Normal
X
meiosis 2
l l
Non-disjunction
X in meiosis 2
ll
XX
Normal
XX meiosis 2
ll ll
back

11. Significance of mutation
• Most are neutral
• Some are harmful
– Cause human genetic disorders
– Cause some types of cancers
• Some are beneficial
– Polyploidy plants are larger and stronger
– Mutations lead to evolution in living organisms

12. Example of Genetic disorder
1) Down syndrome
• 47, trisomic 21

14. Example of Genetic disorder
2) Turner syndrome
• 45 chromosome, xo

15. Example of Genetic disorder
3) Klinefelter syndrome
– 47, XXY

16. Example of Genetic disorder
4) Jacob syndrome
– 47, XYY
back

17. Examples of polyploidy
back

19. Examples of polyploid crops
• Triploid crops(3n):
apple, banana, citrus, ginger, watermelon
• Tetraploid(4n) crops: apple, durum or macaroni
wheat, cotton, potato, cabbage, leek, tobacco, peanut, k
innow, Pelargonium
• Hexaploid crops(6n): chrysanthemum, bread
wheat, triticale, oat, kiwifruit
• Octaploid crops(8n): strawberry, dahlia, pansies, sugar
cane, oca (Oxalis tuberosa)