1. General Genetic
Lab 10
Chromosomal Aberration

2. Mutation
Definition :, (genetics) any event that changes genetic structure; any alteration in the inherited nucleic acid (DNA) sequence of the genotype of an organism that can alter the amino acid sequence of the protein encoded by the gene .
- Mutations are caused by radiation ,viruses and mutagenic chemicals
, as well as errors that occur during : meiosis or DNA replication .
- Variations can be caused by mutation.
Mutations causing variation can arise in 2 ways :
1- Numerical abnormalities in chromosomes
2- Structural abnormalities in chromosomes

3. A- Numerical abnormalities in chromosomes ( Aneu-ploidy)
Definition : This occurs when individual is missing either a chromosome from a pair
( monosomy) or has more than two chromosome of a pair
( Trisomy , Tetrasomy ) .
Example:
1- Monosomy : ( 45 chromosome)
Turner Syndrome : have only one sex chromosome (X) and affects in female ( growth – shorter than normal - sexual development -ovaries fail ) .
2- Trisomy :
1-Klinefelter Syndrome :( 47 chromosome)
have one extra sex X chromosome (XXY) and affects in male
( hypogonadism and sterility)
2 - Down Syndrome : (Trisomy 21)
have 3 copies of chromosome 21 ,
Disorder: (Mongolism – week in the bone and muscles – Bore in heart – heavy tongue )

4. Trisomy (XXY) male
Klinefelter Syndrome
Monosomy (X) female
Turner Syndrome

5. B- Structural abnormalities in chromosomes
Type of :
1- Mitotic stopping ( C – metaphase )
Cause : using carcinogenic material ( Cholchisene ) that cause DNA duplicating without dividing in the cell because of the inhibition in the formation of spindles in metaphase
Result : stopping dividing and chromosomal high coiling without facing the poles .
2-Ring Chromosome : that happen in 2 ways
1- Cause : when the end of the short and long arms breaks
Result : The 2 end stick to each other , thus resulting in loss of information
2- Cause : when the 2 ends of the short and long arms stick together usually without loss of material
Result : That ring can cause problems when the cell divides and can cause problems for the individual .

6. 3- chromosome fragments
Cause : Separation of pieces from the main chromosome .
Result : these pieces remind independent without engagement with another chromosome and it lost because it does not has a centromer .
4- Bridges ( Di-centric chromosomes)
Cause : Physical breakage of the DNA molecule in sister chromatid which produce “sticky ends” before replication
Result : make a bridge between the 2 chromosomal sets in anaphase .
6- Sticky chromosomes
chromosome are overlapping , unclear and sticky .

7. 6- Tri-poles
Cause : Partial suppression in spindle formation activity .
Result : pulled in different ways in anaphase .
7- Multi-nucleated
Cause : Failure in the formation of the central plate .
Result : the cell appear with two or more nuclei .

8. A- Multi-nucleated
B,G, J - Fragment
H, I, J : Bridges
C- metaphase

9. Ring Chromosomes

10. Genetic Pedigree