CELL: THE UNIT OF LIFE
1595 – Jansen credited with 1st compound microscope
1655 – Hooke described ‘cells’ in cork.
1674 – Leeuwenhoek discovered protozoa. He saw bacteria some 9 years later.
1833 – Brown descibed the cell nucleus in cells of the orchid.
1838 – Schleiden and Schwann proposed cell theory.
1840 – Albrecht von Roelliker realized that sperm cells and egg cells are also cells.
1856 – N. Pringsheim observed how a sperm cell penetrated an egg cell.
1858 – Rudolf Virchow (physician, pathologist and anthropologist) expounds his famous
conclusion: omnis cellula e cellula, that is cells develop only from existing cells [cells come
from preexisting cells]
1857 – Kolliker described mitochondria.
1879 – Flemming described chromosome behavior during mitosis.
1883 – Germ cells are haploid, chromosome theory of heredity.
1898 – Golgi described the golgi apparatus.
1938 – Behrens used differential centrifugation to separate nuclei from cytoplasm.
1939 – Siemens produced the first commercial transmission electron microscope.
1952 – Gey and coworkers established a continuous human cell line.
1955 – Eagle systematically defined the nutritional needs of animal cells in culture.
1957 – Meselson, Stahl and Vinograd developed density gradient centrifugation in cesium
chloride solutions for separating nucleic acids.
1965 – Ham introduced a defined serum-free medium. Cambridge Instruments produced
the first commercial scanning electron microscope.
1976 – Sato and colleagues publish papers showing that different cell lines require
different mixtures of hormones and growth factors in serum-free media.
1981 – Transgenic mice and fruit flies are produced. Mouse embryonic stem cell line
established.
1995 – Tsien identifies mutant of GFP with enhanced spectral properties
1998 – Mice are cloned from somatic cells.
1999 – Hamilton and Baulcombe discover siRNA as part of post-transcriptional gene
silencing (PTGS) in plants
MAIN PARTS OF THE CELL AND ITS FUNCTIONS
PART FUNCTION
Nucleus Regulates all cell activities
Cell Membrane Is made out of phospholipids and proteins
Mitochondrion Site of cellular respiration "power house"
Lysosome Suicide Sacks that contain digestive enzymes
Rough Endoplasmic Reticulum Contains Ribosomes, transports proteins and other materials
Smooth Endoplasmic Reticulum Contains no ribosomes, stores proteins
Gogi complex (apparatus) Processes and packages proteins
Nucleuolus Dark spot of chromatin in the nucleous where ribosomes are produced
Cytoplasm Colloid that contains water and nutrients and supports the organelles
Organelles The parts of a cell with a particular function
Prokaryotic Cells with no true nucleus and no membrane bound organelles
Eukaryotic Cells that contain a true nucleus and membrane bound organelles
Centrioles Only in animal cells, aid in cell division
Ribosomes Produce Proteins
Chloroplast Found only in plants, site of photosynthesis
Vacuoles Large storage sacks found mainly in plants
Cell Wall Structure in plants made of cellulose that is outside of the cell
membrane
Chromatin Thin strands of DNA and proteins found in the nucleus of a cell.
Cell Smallest unit of life
Cytoskeleton Long protein filaments in the cytosol that support the cell.
