4/9/15

This week the lecture was on Cell Theory and Prokaryote. Before the lesson we were asked to look for the scientists who have contributed to cell theory. After doing research on internet, I had a brief idea on the discovery of cell. Robert Hooke, an English scientist and microscopist was the first person to discover cell. He observed a thin cutting of cork and discovered tiny boxes. He thought that the tiny boxes looked like cell and named it “Cell”. 

Anton Van Leeuwenhoek made his own microscope which can magnify object up to 250X and discovered bacteria and protozoa. He  named them “Animalcules”.

The scientist Theodore Schwann derived 2 theories which are “Cells are organisms and all organism consists of one or more cells.” and “Cell is the basic unit of life.”.

Rudolf Virchow was called The Father of Modern Pathology as he is the founder of social medicine and veterinary pathology. He also derived that “New cells come from pre-existing cells.” .

However, there are exceptional cases to the theories derived. We were asked “Is virus a living organism or non-living organism ?”. Initially my answer is yes and no because virus is in crystal form when it is in the air but it becomes active when it is in a cell. My thought was correct but virus is not considered as a living organism. This contributed to the addition of 4 theories which are “Cell contains hereditary information.” , “All cells are basically the same in chemical composition and metabolic activities”, “All basic chemical and physiological functions are carried out inside the cells. ” and “Cell activities depends on the activities of subcellular structures within the cell.”.

I never learnt about prion and viroid before. However I understood what they are after the lecture. Prion is an infectious protein that is misfolded. This causes the protein couldn’t function and aggregate. It remained in cell and attacked the nervous system as it cannot be degraded by protease. Viroid is a small RNA that consists of 250 nucleotides. It is not coated with protein and will only affect plants. It causes distorted shape in plants.

                                                                                         Potato tubers infected by viroid. 

Although I have learnt prokaryotes, eukaryotes and viruses before but cell theory, prion and viroid are new to me. So in the end f the lessons I still gain a lot of knowledge which makes me feel that I’m improving and getting smarter everyday.