Highlights Introduction (continued)
1. When we think of microbes (bacteria/yeast) involved in food production, a few others have a long history. They include bacteria involved in making yoghurt and cheese. Lactobacillus bacteria produce lactic acid as a byproduct and it is tasty.
2. As noted in the previous lecture, cells are the fundamental unit of life.
3. We can divide cell types into several categories. The ones we will use in this class are a) prokaryotic; b) eukaryotic; and c) archebacteria
4. Prokaryotic cells are distinguished by a) always being unicellular; b) being tiny in size; and c) not having internal organelles, such as a nucleus or mitochondria. Prokaryotic cells are literally 'bags' of proteins and DNA/RNA.
5. Archebacteria are unusual cell types found in harsh environments. They too are unicellular and we won't have much to say about them.
6. Eukaryotic cells are those of higher organisms, such as animals, plants, fungi (mushrooms, for example) and yeast. Most eukaryotic cells are part of multicellular organisms, but some, like yeast, are unicellular. All eukaryotic cells have internal "organs" called organelles. These include the nucleus (where DNA is stored) and the mitochondria where energy is produced.
7. Viruses are not living organisms. To reproduce, they must invade a cell and use components of the cell they invade to make copies of themselves.
8. We use the byproducts of cellular biochemistry in biotechnology. Though most cells on the face of the earth have most of the same reactions, some cells favor production of some molecules more than others do. For example, yeast produce ethanol, though animal cells (such as ours) cannot.
9. The sum of all the biochemical reactions of a cell is known as metabolism. Metabolism can be divided into catabolism (breaks big molecules down into smaller ones) and anabolism (makes big molecules from smaller pieces).
10. Catabolism usually involves oxidation. Oxidation reactions generally produce energy, so catabolic reactions are used by cells to produce energy. We eat food so our body can break it down to obtain energy through catabolism to do things.
11. Catabolism that uses oxygen is called aerobic and catabolism that does not use oxygen is called anaerobic.
12. Anaerobic catabolism produces products like ethanol (beer/wine)l, lactic acid (tasty), butyric acid (bad smell in sweat), and acetic acid (vinegar).
13. An example of aerobic catabolism is glycolysis, which is the process by which glucose is broken down by cells. This breakdown yields energy that cells can use to make things or do work.
14. Biochemical reactions are catalyzed by enzymes. I'll say more about these in the next lecture. In glycolysis, there are 10 reactions to break down glucose and each reaction requires a different enzyme.
15. Energy generated by catabolism is "captured" in the form of ATP. I think of ATP as the "cellular gasoline" since it is the energy source for most of what the cell does.