Lecture_4_1 - Animal adaptations 4th 230 Ecology lecture 27...

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Animal adaptations 4 th 230 Ecology lecture 27 October 2009 th Ed. Organisms come in a very wide range of size, but cells have a much more restricted range. What are the smallest cells and what limits their size? Mycoplasm (bacteria) as small as 0.1 μm or 10 -7 m. The volume is so small the number of copies of parts, such as ribosomes, is presumably difficult to regulate. The smallest human cell is the sperm and the largest is the egg. Most human cells have a volume corresponding to a diameter of 4-20 μm. The ciliates have large single cells, some over ¼ mm and just visible to the naked eye. The maximum size of a cell is limited by the surface area/volume problem. Material must enter a cell through its surface but everywhere inside is expected to be metabolically active. The surface area increases by the square of the length and the volume increases by the cube of the length so large cells have a lot of mass relative to their surface area. All really big organisms are multicellular and “solve” the surface area/volume problem by having tissues and organs that function to collect, distribute and process essential nutrients. Maximum growth rates (doubling time of population) are inversely proportional to size. Ways heterotrophic organisms get energy and materials. Dodder is a heterotrophic plant –it has no chlorophyll and it lives by tapping into plants that are Heterotrophs can be divided into 3 major types: Herbivores (animals that eat living plants), Carniovres (animals that eat other animals) and Detrivores (organisms that utilize dead organisms as their resource). While all organisms are made up of carbohydrate, protein, lipids and nucleic acids there sufficient differences among plants, animals and dead stuff that most species specialize on a particular type of food. Many organisms are much more specialized than these broad classes. In particular insects may specialize on only a single species or a set of close relatives. Animals can’t make the enzymes necessary to digest cellulose (a major carbohydrate of plant material). One strategy is eat a lot, extract the proteins & simple carbohydrates, but let a lot of material just pass thru. Grazers and browsers that are not ruminants (such as the horse) follow
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This note was uploaded on 01/23/2010 for the course BIOS 230 taught by Professor Gibbons during the Fall '08 term at Ill. Chicago.

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Lecture_4_1 - Animal adaptations 4th 230 Ecology lecture 27...

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