Chapter 6 lecture notes
Cell structures (organelles) and the organelle functions.
All health issues/food production are ultimately based on cell function or mis-function.
Units of microscopy micron/um (10-6 m) nanometer/nm (10-9 m) angstrom /A0 (10-10 m).
Cell and its parts very difficult to study too small, 1-20 um . Almost all microscopic technologies involve, staining (cell otherwise is transparent), fixing (don’t want to it decompose or change), make it more solid, place it in wax/freeze) and slice incredibly thin-------all kill the cell and even create false structures a.k.a. “artifacts”.
Almost impossible to visually see the chemical reactions that are a cell’s life duties, or see where they are taking place. Incredible detective and slow (hundreds of years) painstaking scientific discoveries have resulted in our current level of knowledge. It is not absolute, nor complete.
Technology p. 159
Microscope- Hooke 1663 cork/ “cells”
Leeuwenhoek 1683- microscopic organisms in rain water, ponds, rivers
Most had 1 cell
Brown 1831- dense object “nucleus”/kernal/ nut
Schleiden 1839 - plants are made of cells
Schwann 1839 - animals are made of cells
Virchow 1858- saw cells dividing “All cells come from other cells”
Light compound microscope probably first created 1590. Magnification is not a technological obstacle, resolution is. Resolution is the ability to sharply focus and show separation between lines that are extremely close together. The source of illumination’s wavelength determines the resolution. “Visible light”/ROYGBIV is unable to resolve beyond a magnification of 1000x.
Electron microscope invented in 1930’s. See pp. 157. Uses a beam of electrons to “illuminate” the specimen. Beyond lethal “fixing” it also requires the specimen to be in a vacuum. Also coats the specimen in metal powder. Resolution allows magnification of up to 200,000 –1,000,000.
Modern cell theory- a combination of 300 years of research and contributions.
Cell is the basic unit of life and all cells today come from pre-existing cells
Two types of cells
Prokaryote and Eukaryote (pro early & eu good/true karyo nut/nucleus
Prokaryotes – kingdom monera, Eukaryotes- all other kingdoms
Prokaryotes
Bacteria simplest most ancient life form on planet, they are everywhere, soil, air, water, in and on all other life forms. Different species are able to thrive in every ecosytem on planet, hydrothermal vents, anaerobic conditions, you name it, they live there.
See pp. 160 fig. 6.6 cell wall (carbohydrates but no cellulose) plasma membrane, ribosomes, one large circular chromosome (DNA) attached to plasma membrane (no nuclear membrane/nucleus) and a few smaller circular chromosomes (plasmids). A variety of enzymes in the cytosol, but no membrane enclosed organelles.
3 shapes see pp.162. sphere (cocci), rod (bacilli),
corkscrew (spirochete), producers, consumers, decomposers (some are
pathogens-most are not)