Science & Technology in Action

6th Edition

Cells and Cell Culture


This lesson deals with developments in cell culture and its applications. The basics of cell division are summarised and the process by which cells divide a limited number of times is outlined. The lesson also explains what is meant by stem cells, embryonic stem cells, cell lines and cell banking.
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Lesson excerpt

Today we easily take for granted that living things are composed of cells. Yet it was not always common knowledge and indeed the basic ideas took over 150 years to evolve.

1965 Robert Hooke noted the cellular structure of cork (dead plant cells).
1974 Antonie Van Leeuwenhoek observed living protozoa.
1980s Henri Dutrochet proposed that the cell was not just thestructural unit of living things but the functional unitalso, and that new cells arise from other cells.
1983 Barthelemy Dumortier first observed cell division (in plant cells)
1837 Jan Purkyne proposed that animal tissues were also composed of cells.
1879 Walther Flemming noted that chromosomes 'split' during mitosis.
1887 Wilhelm Roux proposed that chromosomes carriedhereditable traits. He was also the first to carry outtissue culture.
1904 Theodor Boveri worked with sea urchins embryos and showed that a full set of chromosomes was necessary for normal development.
1953 From the early 1900s the chemical structure of chromosomes was gradually clarified and eventually published in 1953.

Cell Division
As cells grow they take in various raw materials which they use to construct complex biomolecules such as proteins, lipids, DNA andRNA. Cells multiply by binary fission, i.e. they split into two smaller cells, known as daughter cells. During cell division the chromosomes, which are composed of DNA, replicate − that is, a copy of each chromosome is formed and one of each goes to each daughter cells.

Structure of Cells
Animal cells such as nerve cells, muscle cells and skin cells are not all alike but they do have some characteristics in common. They typically have an outer cell membrane; inside this there iscytoplasm, a nucleus, mitochondria and other organelles. During the growing stage of a cell the chromosomes (DNA) stay in the nucleus.

Plant cells, in addition to a cell membrane, generally have an outer cell wall which is made mainly of cellulose; often there is a primary and a secondary cell wall. The cell wall of fungal cellscontains chitin, whose structure is similar to that of cellulosealthough it contains amino groups.

True or False?

  1. The cell is the functional and structural unit of living organisms true
  2. Half the set of chromosomes is sufficient for normal development. false
  3. The cells that result from binary fission are called ‘daughter cells’. true
  4. Plant cells generally have two cell walls in addition to a cell membrane. true
  5. Cells of prokaryotes, such as bacteria, contain a nucleus. false
  6. The telomeres at the ends of chromosomes are not fully replicated during mitotic division. true
  7. When a stem cell divides a stem cell and non-stem cell are produced. true
  8. Skin cells, liver cells and muscle cells are differentiated. true
  9. Cells that can produce any other kind of cell are said to be ‘totipotent’. true
  10. Most stem cells are totipotent. false