Lab 2 - PLB 105 Lab ManualFall 2009 page 2-1 Laboratory 2...

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PLB 105 Lab Manual—Fall 2009 page 2-1 Laboratory 2 The Plant Cell, Xylem Regeneration Experiment-part 1 In today's laboratory session you will examine a few selected plant cell organelles and ergastic substances. In addition to examining the structure of these structures, you will set up an experiment to regenerate xylem tissue within a wounded stem. A. The Plant Cell—Plastids and Ergastic Substances Understanding the contemporary science of plant anatomy is, to a large extent, founded on a thorough grasp of plant cell structure. Becoming familiar with the structure and function of individual plant cells, including their intracellular organelles and cell walls, will enhance your understanding of the organization of plant tissues and tissue systems. Today, a few of these cellular features will be emphasized. Not all organelles are easily distinguished at the resolution of a light microscope. However, many are visible, and a visible organelle that is familiar to all of you is the green plastid called a chloroplast. Two types of plastids that may not be as familiar are the chromoplast and the amyloplast. In this section of today's lab you will examine these three plastids and a selection of crystals commonly encountered in plant cells. 1. Plastids Plastids are derived from the proplastids of meristematic cells. Proplastids are self- replicating and may mature into any of numerous types of plastids. Plastid type is mainly dependent upon the presence or absence of pigment and the type of pigment. For example, chloroplasts contain chlorophyll and leucoplasts lack pigments but specialize in storing plant products such as starch (amyloplast) or fats (elaioplast). A plastid may exhibit characteristics of more than one type of plastid and plastids may change types. The type of plastid present is chiefly determined by the type of cell in which the proplastid matures. a. Chloroplasts Remove a leaf from the outer region of the terminal bud of Elodea and carefully mount the section in a drop of water on a microscope slide. Add a coverslip. First examine the leaf under low magnification, noting that the regions on either side of the midrib are thin and composed of only two layers of cells. At high magnification, examine a number of cells within this thin region. Locate the numerous, small, discoid, green chloroplasts. What is the location of chloroplasts within each cell? Can you detect cytoplasmic streaming? Can you find the nucleus? Make a labeled
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This note was uploaded on 12/25/2009 for the course PLB 9876655 taught by Professor Canington during the Spring '09 term at UC Davis.

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Lab 2 - PLB 105 Lab ManualFall 2009 page 2-1 Laboratory 2...

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