Cell biology:a brief history

Cell biology:a brief history

1. Molecular Cell Biology: A brief history

2. Cells can be observed with microscope The discovery of cells is generally credited to Robert hooke He was an English microscopist who at age of 27, awarded the position of curator of Royal Society of London. In 1665, he took a good clear piece of cork and then examined it with a microscope. Hooke called the pores as cells. He observed the empty cell walls of dead plant tissue .

3. Anton van Leeuwenhoak , a dutchman who used to grind lenses and thus constructed simple microscope. He was first to examine a drop of pond water under microscope and observe the teeming microscopic particles named “ animacules ”. He was also first to describe various forms of bacteria, which he obtained from water and from scrapings of his teeth. He wrote some letters to the Royal society describing this previously unseen world, where Robert Hooke confirm the observations.

4. In 1838, Matthias Schleiden , a German botanist concluded that plants were made of cells and that the plant embryo arose from single cell. In 1839, Theodore Schwann, a German zoologist published a comprehensive report on cellular basis of animal life. He concluded that the cells of plants and animals are similar structure and proposed the cell theory: All organisms are composed of one or more cells. The cell is the structural unit of life.

5. In 1855, Rudolf Virchow, a German pathologist, made a convincing case for the third tenet of the cell theory and stated that calls can only arise by division from a pre-existing cell.  In 1857, Albert von Kölliker described what he called “granules" in the cells of muscles. Richard Altmann in 1890, established them as cell organelles and called them " bioblasts ". The term "mitochondria" was coined by Carl Benda in 1898 . Flemming was the first to detail the chromosomal movements in the process of mitosis. In 1879, Flemming used aniline dyes, a by-product of coal tar, to stain cells of salamander embryos. He was able to visualize the threadlike material as the cells divide .  He saw that chromosomes were "doubled" when they appeared in prophase, and "solved" the problem of chromosomal partitioning between mother and daughter cells.

6. I n 1885 Weismann had published "The Continuity of the Germ- Plasm as the Foundation of a Theory of  Heredity“. He stated  that only the hereditary substance of the  germ cells was inheritable, and that cells that derive from all other parts of parents' bodies (soma cells), could not transmit from parents to offsprings . The existence of the cell organelle which is now known as Golgi apparatus or Golgi complex, or simply as 'the Golgi", was first reported by Camillo Golgi in 1898, when he described in nerve cells an 'internal reticular apparatus' impregnated by a variant of his chromoargentic staining. 

7. In 1951 George and Martha Grey of Johns Hopkins University, successfully made the first continuous cell line culture of Human cells. The cell line was derived from the cervical cancer cells of Henrietta Lacks, thus these cells were referred to as HeLa cells. Hela cells- descended by cell division from this first cell sample are still being grown in laboratories around the world today.

8. In 1919 Phoebus Levene , a Russian physician and chemist, first discovered the order of the three major components of a single nucleotide (phosphate, pentose sugar, and nitrogenous base). He was also the first to discover the carbohydrate component of RNA (ribose), and carbohydrate component of DNA ( deoxyribose ). In 1950 , scientist named Erwin Chargaff noted the nucleotide composition of DNA molecule among species and postulated the “Chargaff’s Rule” which says that the amount of cytosine is equal to the amount of guanine, and the amount of thymine is equal to the amount of adenine. In 1953 James Watson and Francis Crick derived the three-dimensional and double helical model of the DNA.

9. 1956 George Emil Palade showed the site of enzymes manufacturing in the cytoplasm is made on ribosomes. 1957 – Meselson , Stahl and Vinograd developed density gradient centrifugation in cesium chloride solutions for separating nucleic acids. 1958 The Meselson -Stahl demonstrate that DNA is semiconservatively replicated. In 1970, Smith and Kent W. Wilcox discovered the first type II restriction enzyme , HindII . 1970 Reverse transcriptase in retroviruses was first discovered. 1972 Paul Berg used a restriction enzyme to cut DNA and ligase to join two DNA strands together to form hybrid circular molecule.

10. 1977, Frederick Sanger introduced the process of  DNA sequencing. The first ever organism to have its genome sequence is a bacteriophage . 1980, The Polymerase Chain Reaction, a method used to amplify a copy of a segment of a DNA was inverted by Kary Mullis. 1986, the term “Genomics” appeared for the first time to describe the scientific discipline of mapping and analysing genes. 1986 Leroy Hood: Developed automated sequencing mechanism. 1986 Human Genome Initiative was announced. 1995 Moderate-resolution maps of chromosomes 3, 11, 12, and 22 were published. These maps provide the locations of “markers” on each chromosome to make locating genes easier.

11. 1995 John Craig Venter: First bacterial genomes sequenced. 1995 Automated fluorescent sequencing instruments and robotic operations . 1996 First eukaryotic genome-yeast-sequenced. 1999 First Human chromosomes (number22) sequenced. April 2003 Human Genome Project was Completed.

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