Lecture 01, 2

• What are chromosomes?

  Rod-shaped bodies in the nucleus
• What is the role of chromosomes?

  Carriers of genetic information
• When are chromosomes visible?

  During cell division at metaphase
• What does chromosome morphology refer to?

  Structure and appearance of chromosomes
• What are chromosomal abnormalities?

  Visible alterations in chromosome structure
• What are some clinical indicators for chromosomal analysis?

  Multiple congenital abnormalities, infertility
• What is a karyotype?

  Number and appearance of chromosomes
• What is G-banding used for?

  Diagnosis of chromosomal abnormalities
• What does heterochromatin stain look like?

  Darker than euchromatin
• What is the function of colchicine in chromosome analysis?

  Halts cell division at metaphase
• What is an ideogram?

  Illustration of chromosome sizes and patterns
• How are chromosomes classified based on morphology?

  Metacentric, submetacentric, acrocentric, telocentric

  
• What defines a metacentric chromosome?

  Equal length arms with centromere in middle

  
• What is polyploidy?

  Presence of multiple sets of chromosomes
• What is aneuploidy?

  Abnormal number of chromosomes
• What are structural abnormalities in chromosomes?

  Alterations like deletion, duplication, translocation
• What is trisomy?

  Presence of an extra chromosome
• What is the significance of FISH in cytogenetics?

  Maps DNA sequences to chromosome regions
• What is the average age at death for individuals with Down syndrome?

  49 years
• What is the purpose of prenatal chromosomal analysis?

  Identify chromosome abnormalities in fetuses
• What is chorionic villus sampling (CVS)?

  Tissue sample taken from the placenta
• What is the role of amniocentesis?

  Tests cells in amniotic fluid for abnormalities
• What does nuchal translucency ultrasound measure?

  Fluid at the back of the fetal neck
• What is preimplantation genetic diagnosis (PGD)?

  Tests embryos for heritable genetic conditions
• What is the purpose of molecular cytogenetic techniques?

  Detect small chromosomal changes
• What does cell-free fetal DNA (cffDNA) screening detect?

  Foetal aneuploidies in maternal blood
• What is the significance of the 47 chromosomes in Down syndrome?

  Indicates trisomy 21
• What is the risk factor for Trisomy 13 (Patau's syndrome)?

  Increased risk in mothers over 35 years
• How do reciprocal translocations differ from Robertsonian translocations?

  Reciprocal involves exchange, Robertsonian involves fusion

  
• What is the outcome of large deletions in chromosomes?

  Observable under a microscope after staining