Understanding Chromosomal Aberrations and Mutations in Genetics
Chromosomal aberrations and mutations are key events that can alter the genetic structure of organisms. They can lead to numerical abnormalities like aneuploidy and structural abnormalities such as ring chromosomes and chromosome fragments. Understanding these variations in chromosomes is crucial in genetic studies.
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Lab 10 Chromosomal Aberration
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
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 )
Trisomy (XXY) male Klinefelter Syndrome Monosomy (X) female Turner Syndrome
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 .
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 .
6- Tri-poles Cause : Partial suppression in spindle formation activity . Result : pulled in different ways in anaphase . Vorschaubild der Version vom 23. Februar 2008, 23:31 Uhr 7- Multi-nucleated Cause : Failure in the formation of the central plate . Result : the cell appear with two or more nuclei .
A- Multi-nucleated B,G, J - Fragment H, I, J : Bridges C- metaphase
