1. Mutations

2. What is a mutation?
Changes in the genetic material

3. Mutations can occur in two different types of Cells:
1. Somatic (body) cells
2. Gamete (sex or germ) cells

4. Significance of Mutations
Most mutations are neutral, meaning they have little or no effect on the expression or function of the proteins they code for
Those that cause dramatic changes produce defective proteins that disrupt biological activities
However, mutations are the source of genetic variability in a species, which can be highly beneficial

5. Harmful Mutations Causes Genetic disorders
ex: sickle cell anemia, cystic fibrosis, hemophilia, muscular dystrophy and down syndrome (or trisomy twenty one)
Causes different Types of cancer

6. Kinds of Mutations I. Gene Mutations- II. Chromosomal Mutations-
produce changes in a single gene
II. Chromosomal Mutations-
produce changes in the whole chromosome

7. I. Gene Mutations
Point Mutation- changes in one or a few nucleotides within the DNA sequence
Substitutions-one base is changed to another
Frameshift Mutation- A single nitrogen base is deleted or inserted from the DNA sequence causing a shift in the “reading frame” of the genetic message.
Insertions-one base is inserted
Deletions-one base is deleted

8. Gene mutations continued
Example: substitution
THE FAT CAT ATE THE RAT
THE FAT CAT ATE THE HAT
Example: insertion
THE YFA TCA TAT ETH ERA
Example: deletion
TEF ATC ATA TET HER

9. Point Mutations: Small Scale Mutations
usually effect no more than one amino acid
THE FAT CAT ATE THE RAT
THE FAT CAT ATE THE HAT

10. Frameshift Mutation Frameshift is usually more dramatic
May change every amino acid that follows the point of insertion or deletion
THE FAT CAT ATE THE RAT
TEF ATC ATA TET HER AT

11. Review What are the three parts of a nucleotide?
What are the four bases?
How many bases code for an amino acid?
What is made by joining amino acids?
What are genes?
Where are genes?

12. The effects of insertions or deletions
Which one usually effect no more than a single amino acid?
substitutions
What happens if a nucleotide is added or deleted?
the “reading frame” or code is shifted from that point on which is a frameshift mutuation.
Which one alters a protein so much that it is not able to perform its normal function?
frameshift

13. Kinds of Mutations I. Gene Mutations- II. Chromosomal Mutations-
produce changes in a single gene
II. Chromosomal Mutations-
Involve changes in the number or structure of chromosomes which change the location of genes or the number of copies of genes

14. Two Types of Mutations 2. Chromosomal Mutations 1. Gene Mutations
A. Point Mutations
B. Frameshift Mutations
A. Deletion
B. Duplication
C. Inversion
D. Translocation
E. Non-disjunction

15. Ex: original chromosome A B C * D E F
Deletion: A B * D E F
Duplication: A B B C * D E F
Inversion: A E D * C B F
Translocation: A B C * J K L
G H * I D E F

16. Chromosomal Mutations
Deletion- loss of all or part of a chromosome
Duplication-production of extra copies of parts of the chromosome
Inversion- reverses the direction of parts of a chromosome
Translocation- part of one chromosome breaks off and attaches to another chromosome
Non-disjunction- means “not coming apart”. When homologous chromosomes fail to separate properly during meiosis (cell division producing gametes)

17. Non-disjunction- Chromosomal mutation
A karyotype generally has two chromosomes at each position (23 pairs)
Trisomy (3) means a person has an extra chromosome
Monosomy (1) means a person is missing a copy of a chromosome.

18. Trisomy 21- Down Syndrome Karyotype (47XY)

19. Klinefelter’s Karyotype (47XXY)

20. What is Klinefelter syndrome?
Klinefelter syndrome is a chromosomal condition that affects male physical and cognitive development. Its signs and symptoms vary among affected individuals.
Affected individuals typically have small testes that do not produce as much testosterone as usual. Testosterone is the hormone that directs male sexual development before birth and during puberty. A shortage of testosterone can lead to delayed or incomplete puberty, breast enlargement (gynecomastia), reduced facial and body hair, and an inability to have biological children (infertility).
Older children and adults with Klinefelter syndrome tend to be taller than their peers.
Children with Klinefelter syndrome may have learning disabilities and delayed speech and language development. They tend to be quiet, sensitive, and unassertive, but personality characteristics vary among affected individuals.

21. Turner’s Syndrome Karyotype (45XO)

22. What is Turner’s Syndrome?
Turner syndrome is a chromosomal condition that affects development in females. The most common feature of Turner syndrome is short stature, which becomes evident by about age 5. An early loss of ovarian function (ovarian hypofunction or premature ovarian failure) is also very common. The ovaries develop normally at first, but egg cells (oocytes) usually die prematurely and most ovarian tissue degenerates before birth. Many affected girls do not undergo puberty unless they receive hormone therapy, and most are unable to conceive (infertile). A small percentage of females with Turner syndrome retain normal ovarian function through young adulthood.

23. Mutations and Natural Selection
Examine the diagram
Does natural selection work on the genotype or phenotype?
Natural selection leads to a change in the “population” NOT the individual.

24. Beneficial Mutations
Produce proteins with new and altered activities that are useful in changing environments (gene resistant)
Plant and animal breeders take advantage of these mutations (genetically altered)
Polyploid plants- produced when chromosomes fail to separate during meiosis. Result in triploid (3N) and tetraploid (4N) organisms.
Polyploid plants are often larger and stronger than diploid plants.