Bio Tech-Talks by Dr. Abhimannue

  Karyotyping is a laboratory technique used to visualize and analyze the number, size, and shape  of chromosomes in a cell. This process is essential for detecting chromosomal abnormalities that  can lead to genetic disorders. Karyotyping is typically performed on cells in the metaphase stage  of mitosis when chromosomes are most condensed and easily visible under a microscope.  Steps in Karyotyping  1. Sample Collection:  o Sources: Common sources of cells for karyotyping include blood (white blood  cells), bone marrow, amniotic fluid (for prenatal testing), or tissue samples. o Cell Culture: The collected cells are cultured in a laboratory to increase their  number and ensure that a sufficient number of cells are in the metaphase stage. 2. Cell Harvesting:  o Arresting Mitosis: Cells are treated with a mitotic inhibitor like colchicine,  which stops cell division at metaphase, where chromosomes are most visible. o Hypotonic ...

  PREPARATION OF BUFFER & pH ANALYSIS A buffer solution resists changes in pH upon the addition of small amounts of acid or base. It typically consists of a weak acid and its conjugate base or a weak base and its conjugate acid.  Common buffer systems  Acetic acid/acetate (pH ~ 4.76) – acidic buffer Phosphate buffer (pH ~ 7.2) – neutral buffer Ammonium/ammonia (pH ~ 9.25) – basic buffer Henderson-Hasselbalch Equation is used to calculate the ratio of acid and base: pH=pKa+log⁡((A−)/(HA)), where:  [A−] = concentration of conjugate base [HA] = concentration of weak acid PREPARATION OF 0.1 M TRIS-HCL BUFFER  Objective: To prepare 0.1 M Tris-HCl buffer at pH 7.4 and verify its pH  Theory: Tris is a weak base. When mixed with HCl, it forms the conjugate acid (Tris-HCl), creating a buffer. The pKa of Tris is ~8.1 at 25°C, making it ideal for buffers in the pH 7–9 range. Materials Required:  Tris Base (MW = 121.14 G/Mol) Concentrated HCl (~12 N) Distilled...