Cytogenetics: Origin and Importance

Study Notes

Cytogenetics studies chromosomes, their abnormalities, and associated diseases.
Cells are the basic structural and functional unit of all organisms, housing hereditary factors known as genes.
Abnormal chromosome number and structure can affect organism traits and development.

Cytology: Study of cells.
Genetics: Study of heredity.
Modern cytogenetics extends to molecular levels, leading to biochemical and molecular genetics.

Transmission Genetics: Focuses on gene transmission from parents to offspring affecting traits.
- Key questions explore chromosome transmission, inheritance patterns.
Molecular Genetics: Examines genetic material at the molecular level including DNA structure, replication, and mutation.
Population Genetics: Studies genetic variation within populations and factors affecting allele prevalence.
- Investigates natural selection impacts, environmental contributions to traits.

By the mid-19th century, cell division was recognized as critical in reproduction.
Omnis cellula e cellula: Theory by Virchow emphasizing cell continuity.

Gregor Mendel (1865): Formulated the Fundamental Laws of Heredity through pea plant experiments.
Theodor Boveri (1890): Proposed chromosomes' role in inheritance.
Archibald Garrod (1902): Identified that some diseases are inherited.
Thomas Hunt Morgan (1910): Confirmed that genes are on chromosomes, revealing sex-linked traits.

1953: Watson and Crick proposed the double-stranded helix structure of DNA.
1983: Kary Mullis discovered Polymerase Chain Reaction (PCR), amplifying DNA segments.
2003: Completion of the Human Genome Project, mapping human genes.

Cellular organization is present in all living organisms except viruses.
Unicellular Organisms: Composed of a single cell (e.g., bacteria, protozoa).
Multicellular Organisms: Composed of multiple cells (e.g., plants and animals).

Prokaryotic Cells: Primitive, simple, and lack defined organelles; believed to have existed for 3.5 billion years. Example: Bacteria.
Eukaryotic Cells: More complex, with a nucleus; believed to have evolved from prokaryotic cells about 1.4 billion years ago. Found in plants and animals.