Foundational & Next generation Lab Tech

Key Terms

Primer - The history of cellular and molecular biology

Karyotyping: observing the structure and number of chromosomes across a whole genome, usually derived from white blood cells

Constitution - main genome in the body


Primer

The history of cellular and molecular biology


Primer A.

  • Prior to the 1800s the structures within living things were not understood

  • This limited the understanding and treatment of disease


    To study Cell Biology we needed the first foundational laboratory Technology: the microscope


  • Robert Hooke’s book Micrographia (1665) contained main studies using light microscopes

    • He was the first use of the term “cell” to mean observable biological units


  • origincal microscipes has limited magnification

    • 50x - 100x

•This changed biology from speculative (supernatural) to an observational science (evidence-based)

•Between 1700 and 1900 a huge body of work appeared where various organisms and tissues were studied

•Notably in 1831 Robert Brown observed and reported the nucleus, which marked the humble beginning of genetics


Primer B

  • •The beginnings of genetics involved mathematics rather than technology

    •Following Brown’s observation of nuclei, a hypothesis emerged that cells “inherited” information from one another

    •The idea of a “unit of inheritance” was debated, until the start of the 20th Century.

The process of histopathology

As of the 1950s pathologists and scientists using microscopes routinely, as part of histopathology


  1. gross dissection of a sample or full autopsy

  2. microtome and paraffin embedding

  3. then staining


Fixatives

  • Cryogenic

    • freeze water in the unfixed tissue

  • formalin fixes paraffin embedding (FFPE)

    • water in the tissue is slowly removed by paraffin wax, takes hours

  • plastic embedding for LM and EM

    • water in the tissue is replaced by plastics (Methacrylate or araldite), may take days to complete


Sectioning

  • the wax block is placed on the block

  • move it back to the blade

  • move the handle

  • to create the ribbon


Staining slides

  • staining adds contrast to the cell

  • certain dyes were developed in the 1800s

  • the most used stain is the H&E stain

    • this stains the nucleus and cytoplams



Limitations

  • diseases are systemic and do not lead to cellular changes

  • understanding the root cause of diseasecan help create new treatments


Genetics now a big part of Medicine. DNA, RNA, and proteomics are used alongside traditional pathology to reveal unobservable faults


Mendel

  • Farmers and animal breeders knew of “desirable traits”, but the idea had not been scientifically assessed

  • Gregor Mendel (1822-84) was an Austrian monk interested in botany

  • Focusing on pea plants, he counted fractions of different plant height, flower colour, shapes of pea pods, etc noting how they were inherited generation by generation

This concept became the field of ”Mendelian Genetics”

Discovery of structure of DNA

  • Although Mendel demonstrated that genetic units existed, it took another 60 years for DNA to be revealed

  • In 1953 James Watson and Alexander Crick published the double helix structure in the journal Nature

  • Maurice Wilkins, English chemist Rosalind Franklin produced the x-ray diffraction data that likely inspired their work


The first genetic technologies

• The structure of DNA was now understood. DNA/Nuclei can be seen down a microscope. However, DNA sequences cannot be “read” by eye

• Fortunately, a link to diseases could be made: DNA mutations vary dramatically in size, small to large and complex


Genetics and Laboratory Technologies

Theodore Boveri is often cited as the first to describe chromosome changes (in Sea Urchins of all things)

However, using microscopes and cultured cells, Peter Nowell observed chromosomes and in the context of pathology and medical diagnosis of leukaemia


Karyotyping

metaphase Finding

  • hold the cell so they don;t divide

  • and then culture them so they are synchronised

  • when they are at there clearist, add in a chemicla to stop them divivding

  • uses a metaphase funder - which is a robot.