classnotes3 - Part I Nutrition I How to obtain food This is...

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Part I - Nutrition. I. How to obtain food: This is descriptive - general zoologists might be interested in this. suspension feeders - whales, gills, clams. substrate feeders - live in or on food source fluid feeders - mosquitos bulk feeders - eat large pieces of food. (what about parasites (substrate feeders)? corals?) II. What kind of food: plant (herbivore) animal (carnivore) both (omnivore) also - note that food can be live or dead or “in between”: - carrion/fungus/(mention parasitoid wasps) III. Reason for feeding: 1) to obtain energy! Biological organisms need energy. Most biological molecules have some kind of energy associated with them (Krebs cycle). -plants get energy from sunlight (usually) => autotrophic. -animals get energy from other organisms (usually) => heterotrophic. -some strange bacteria get energy from heat or other sources (they're also autotrophic). 2) to get raw materials for synthesizing needed compounds (differs from # 3, since these are “raw” materials). 3) to get essential nutrients that can’t be synthesized (a little similar to # 2, but these materials are not synthesized). The details: i) Energy: Energy is obtained by oxidation of organic molecules. Remember the Krebs cycle - demonstrates how ATP is produced in the presence of oxygen from organic molecules. Primary molecules for providing energy are:
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i) fats ii) carbohydrates iii) proteins Fats give about twice the energy of the other two. ii) Energy balance - short term: Excess energy is stored as glycogen (consists of glucose sub-units) in the liver (and muscle). If energy is needed, glycogen is released and metabolized (oxidized). iii) Energy balance - long term [Fig., not in book] : Excess energy is stored as fat. Great for living through rough times, but in U.S. (fortunately) we have more than enough food to go around. Result = > obesity is a serious problem (has very negative influences on health). - diet and exercise are huge industries in the U.S., partly due to the obesity
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classnotes3 - Part I Nutrition I How to obtain food This is...

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