1. List and briefly describe two direct and two indirect methods of counting mic
ID: 9387 • Letter: 1
Question
1. List and briefly describe two direct and two indirect methods of counting microbes.3. Discuss the terms used to classify organisms according to their sources of energy and carbon.
4. Cellular respiration of glucose results in the production of 38 ATP. At the end of the Krebs cycle the breakdown of glucose to carbon dioxide and water is completed, yet only 4 molecules of ATP have been made. Explain how the other 34 molecules of ATP are produced.
5. Most photosynthesizing cells conduct non-cyclic photophosphorylation. However, green and purple
sulfur bacteria conduct cyclic photophosphorylation. Summarize the differences.
6. Most cells conduct glycolysis to produce a net of 2 ATP from glucose. The pentose phosphate pathway is
also used by most bacteria, yet it yields only 1 ATP from glucose. What are the benefits to using the pentose
phosphate pathway to catabolize some glucose?
7. Briefly discuss lipids or proteins metabolism by cells.
8. Cells that ferment have extracted all the ATP they can get out of a glucose once two pyruvate molecules are
produced. However, these cells must conduct at least one additional step, resulting in a waste product, such as acid or alcohol. Explain.
9. List and briefly describe differences between selective and differential media, enrichment.
Explanation / Answer
1. To count microbes - Indirect methods - Turbidometry, metabolic activity Direct method - Membrane filter, plate count, coulter counter. 3. Classification of microbes depending on Source of energy - phototrophs, chemotrophs. Source of carbon - organotrophs, inorganotrophs. 4. 34 ATPs produced from the electron transport pathway, in which the NADH2 and FADH2 produced in the glycolysis and krebs cycle are enetered ETC. These will produce protons that are used to produce ATP by forming proton gradient across the mitochondrial membrane. NADH2 - 3 ATP, FADH2 -2ATP 5. Cyclic photophosphorylation - The electrons released by P700 of PS-I in the presence of light are taken up by the primary acceptor and are then passed on to ferredoxin (Fd), plastoquinone (PQ), cytochrome complex, plastocyanin (PC) and finally back to P700 i.e., electrons come back to the same molecule after cyclic movement. Non -cyclic photophosphorylation - The electrons lost by P680 (PS-II) are taken up by P700 (PS-I) and do not get back to P680 i.e., unidirectional and hence it is called non- cyclic phosphorylation. 6. Pentose phosphate pathway is essential to the cell, because it is the only pathway through which the NADPH2 is produced, and they are essential for the maintainance of RBC membrane integrity. 7. Lipids are metabolised by the cell, through beta oxudation and lipolysis. Acetyl CoA is the precurssor molecule in the synthesis. Enzymes play vital role in the process. Proteins are cleaved by the proteases and synthesiszed in the body by the process of translation and from amino acids. 8. Cell must undergo anaerobic process inorder to synthesize a waste product of acid or alcohol. This process is known as fermentation. Dehydrogenase play an important role in this reactions. 9. Selective media is used for the purpose of selection of respective microbes from a crude extract of microbes. Differential media is used to differentiate between two types of bacteria. Enrichment media is used to culture specific bacteria, which is grown very favorable on it.Related Questions
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