Unit04 - Unit 4 in Entomology[1 Unit 4 Integument...

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Unit 4 in Entomology [1] Unit 4 Integument, Development and Reproduction. [2] Have you ever watched a butterfly emerge from its cocoon? How does it go from being a little worm like caterpillar in to a beautiful butterfly with scaled wings and a different type of mouth part and different legs? Well, if you've ever watched this amazing process, you may have wondered how it happens. In this unit you will study the molting process, including all of the hormones involved. First, you'll need to learn about some of the structures and the composition of the exoskeleton. In the final portion of this unit, you learned about the insect reproductive system and how insects propagate their kind. [3] There are five objectives in this unit, by the end of this unit you should be able to: describe the layers of the integument, tell me why tell me why having an exoskeleton would be advantageous and disadvantageous. You should be able to use the proper terms for the structures involved in molting and explain all the steps in the molting process. You should explain the role of some of the chemicals, juvenile hormone and ecdysone, tell me where they come from and how they're used together during molting. Should also, be able to identify the internal and external reproductive structures of insects and describe what they do or what they're used for. [4] In unit one, you learned that arthropods have an outer exoskeleton made up of chitin and proteins. Well, it’s a little more complex than that. The exoskeleton is also called the cuticle and is made up of three distinct layers: the epicuticle, exocuticle and endocuticle. The top layer is extremely thin, it's the epicuticle, and it's the protective waterproof layer made up of fats and polyphenols. The exocuticle is the hardened layer, it consists of a chitin-protein matrix made of microfibers linked together that forms like a plastic kind of material. The innermost layer of the cuticle is flexible, it's the endocuticle. It's also made of chitins and protein but they're not linked together to form a hard layer, it remains flexible. The cuticle is only made of chitin and proteins, it's not made up of cellular material. Directly below the cuticle is the cellular layer called the epidermis. The epidermis is very important because those cells are the source of the proteins, chitins, lipids, and all the other products contained in the exoskeleton in other words, the epidermal layer, the cellular layer supplies all the materials needed for the Endo, exo, and epicuticle. When an insect molts these cells play a critical role, because they have to replace all of those ingredients needed to form the exoskeleton. [5] The cuticle and epidermis make up what we call the insect's integument. Below the integument is a basement membrane. Scientists aren't really clear what makes up this layer but we do know that this layer separates the epidermal cells from the insect's blood, the hemolymph. The membrane has pores large enough to allow proteins and other molecules in the blood to pass through the membrane and on to
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This note was uploaded on 07/23/2011 for the course ENY 3005 taught by Professor Staff during the Spring '08 term at University of Florida.

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Unit04 - Unit 4 in Entomology[1 Unit 4 Integument...

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