|Lecture Notes: 24 January||
Cool facts about E. coli :70% water, 15% protein, 7% nucleic acids, 3% polysaccharides, 3%, lipids, 1% inorganic ions, & 0.2% metabolites.
Complex, generalized organisms such as E. coli exhibit an amazing level of redundancy in enzymes etc. For example, of the approximately 4,000 genes in E. Coli less than 300 have been found to be "essential," where essential means the organism cannot grow on rich medium if the gene is deleted. Many genes also appear to be "silent: under more restrictive conditions as well - that is the organism often has more than one pathway to accomplish a given metabolic activity. (Cornish-Bowden & Cárdenas, Nature 14 Nov 2002, p 129)
Compartmentation in Eukaryotes
As mentioned earlier we will be focusing on eukaryotes in the rest of this course. 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 in a "typical" liver cell. [overhead-Animal cell]
Let's look at a "typical" plant cell for a moment. All of the organelles we saw in animals are here as well, but with a few additions: [overhead-Plant cell]
Water is a very unusual, even incredible substance whose amazing properties are often unappreciated because of its ubiquitousness. Water's special properties include extremely high mp and bp (0 °C & 100 °C K, compare to methane, -183 °C & -161 °C, with a MW of 16 vs. water's 18); a high heat capacity (18 cal/°C mol vs. 8 cal/°C mol for methane); it has a high viscosity; its solid form is less dense than the liquid form at the same temperature (ice floats on water - very rare), it has a large surface tension, and it has a high dielectric constant (78.5 vs. 1.9 for hexane).
Last modified 24 January 2007