Cytogenetic module 1

• Cytogenetics is the branch of Genetics that studies the cell specifically the chromosome
• Developed from cytology and genetics
• Deals with the structure, number, function, and movement of chromosomes and variations affecting gene transmission
• Fields of Genetics include:
• Replication, expression, recombination, and mutation of genes are studied
• Transmission genetics: concerns with the transmission of genes from parent to offspring
• Molecular genetics: studies genetic works at the molecular level, including gene replication, expression, regulation, and mutation
• Population genetics: focuses on genetic variation within a population and the role of the environment in trait outcomes
• Clinical applications of Cytogenetics:
• Diagnosis, prognosis, and monitoring of diseases like leukemia and solid tumors
• Prenatal and postnatal genetic testing for congenital abnormalities and genetic disorders
• Gene mapping to identify gene locations in chromosomes for diagnosing genetic diseases
• Therapeutic management including gene therapy
• DNA fingerprinting for paternity testing and forensic purposes
• Brief History:
• Gregor Mendel (1865-66): Father of Genetics, studied heredity through pea plant experiments
• Walther Flemming (1882): Founder of Cytogenetics, discovered mitosis
• Theodore Boveri (1890): Developed the chromosomal theory of inheritance
• Oswald Avery, Colin McLeod, Maclyn McCarthy (1944): DNA identified as the hereditary material
• James Watson and Francis Crick (1953): Described DNA structure as a double helix
• Kary Mullis (1983): Discovered Polymerase Chain Reaction (PCR)
• 1990: Human Genome Project launched to provide a complete human genome sequence
• Introduction to Cytology:
• General types of cells: Prokaryotes (e.g., bacteria) and Eukaryotes (e.g., human, plants)
• General types of human cells: Somatic cells (all body cells except sex cells) and Sex cells/Gametes (sperm and ova)
• Cell Cycle:
• Cell cycle involves interphase and mitotic or M phase
• Interphase includes G1, S phase, G2, and G0 stages
• Cell division types: Mitosis and Meiosis
• Stages of Mitosis:
• Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis
• Significance of mitosis: Ensures genetic continuity, growth, cell replacement, regeneration, and asexual reproduction
• Stages of Meiosis:
• Meiosis I and Meiosis II with Prophase I, Metaphase I, Anaphase I, Telophase I, and Cytokinesis
• Regulation of Cell Division:
• Significance of meiosis: Increases genetic diversity, new trait combinations, and can lead to chromosomal abnormalities
• Cell cycle checkpoints ensure proper cell division and DNA replication
• Genes regulate the cell cycle through positive (proto-oncogenes) and negative (tumor suppressor genes) mechanisms
• Tumor suppressor gene p53 plays a crucial role in repairing damaged DNA and inducing cell apoptosis
• Defective cell cycle regulation can lead to genetic diseases and cancer