Cytogenetic PDF

LAB.3 genetic Dr.Estabraq Almuhanna ,Dr.Zainab AlKhalidi Cytogenetic Cytogenetics The study of chromosomes and genomic structure, function, and variation and their role in human disease and heredity. Chromosome is a thread like structure found in the nuclei...

LAB.3 genetic Dr.Estabraq Almuhanna ,Dr.Zainab AlKhalidi Cytogenetic Cytogenetics The study of chromosomes and genomic structure, function, and variation and their role in human disease and heredity. Chromosome is a thread like structure found in the nuclei of both animal and plant cells. They made protein and one molecule DNA. Chromosome structure: Chromosome consists of two sister chromatids. Each of which is comprised of compacted double helix of DNA. Centromere: is a constriction visible on metaphase chromosomes where the two sister chromatids are joined. It is function of centromere is essential to the survival of chromosomes during cell division. Telomeres: are the physical ends of chromosomes act as protective cap to chromosome ends. Preventing end-to-end fusion of chromosomes and DNA degradation resulting after chromosome breakage. Telomere contain tandem repeates of TTAGGG Chromatin: complex DNA and protein found in euokaryotype nucleus that packages chromosomes. Chromosomes vary in shape and size and vary in the shape depending position of centromere. 1- Metacentric: the centromere in the middle of chromosome and two arm is equal length. 2- Sub metacentric: the two arms vary in length. 3- Acrocentric: the centromere close to the end. LAB.3 genetic Dr.Estabraq Almuhanna ,Dr.Zainab AlKhalidi techniques were needed to 1. Using cells in culture( fetal calf serm ; is very importent because contain protien that use to growth and division). antibiotic it use in culture media to prevent growth of microorganism. 2. Pre-treating cells in a hypotonic solution, which swells them and spreads the chromosomes. 3. Arresting mitosis in metaphase and destory the spindle fibers so, the two sister chromatids of chromosome still attached by a solution of colchicine. methanol use to fix the chromosom. 4. Squashing the preparation on the slide forcing the chromosomes into a single plane 5. Cutting up a photomicrograph and arranging the result into an indisputable karyogram. Cytogenetics types: 1.Classical Cytogenetics 2- Molecular Cytogenetics 3- Immune Cytogenetics 4- Biochemical Cytogenetics Other classification depended on the aim of the study 1- Human Cytogenetics 2- Animals Cytogenetics 3- Plants Cytogenetics LAB.3 genetic Dr.Estabraq Almuhanna ,Dr.Zainab AlKhalidi Classical cytogenetics of culturing the samples to establish a karyotype to identify abnormalities in the number of chromosomes for example Molecular cytogenetics which is a karyotype complementary technique based on in situ hybridization (ISH).