|Lecture Notes:: 8 October||
Review: Hierarchy from inorganic molecules and ions (water, etc.) to Cells.
Aside - What is a virus? From my perspective a non-living information packet. Contains DNA or RNA, but NO metabolic activity, no energy transfomation, no reproductive machinery etc. At best part of a cell. Operates by subversion of cell machinery to its own ends. [overhead]
To give some perspective, lets look at the relative sizes of these objects. [overhead-sizes of molecules, one million times magnification]
There are two main cell types: prokaryote and eukaryote. A typical idealized prokaryote cell is shown in Figure 7.4 on p 106. [overhead- E. coli cell]
Let's look at E. coli for a moment just to get an idea of its size, and also to get an idea of the sizes of various molecules. Figure 1.25 [overhead- E. coli cell x 100,000] is an artists rendition of a typical E. coli cell, with the various components drawn to scale. Figure 1.26 [overhead- E. coli cytosol] magnifies a square section of that cell another ten times so that particles such as ribosomes, proteins and DNA are readily visible. This view leaves out all of the small molecules though, to simplify the visualization. Finally a corner of the square is magnified a further ten times and water and small metabolites are shown in a very thin slice of our bacterial cell.
Cool facts about E. coli :70% water, 15% protein, 7% nucleic acids, 3% polysaccharides, 3%, lipids, 1% inorganic ions, & 0.2% metabolites.
Typical idealized eukaryote cells are shown in Figure 7.7 on p 108 (animal) and Figure 7.8 on p 109 (plant). [overheads- Animal cell, Plant cell]
Eukaryotes differ from prokaryotes in having a nucleus and cell organelles (their cells are physically compartmentalized). As a point of reference, an E. coli cell is about the size of a typical mammalian mitochondria.
Let's look at where different major metabolic pathways occur. [overhead-Animal cell, Plant cell]