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TA Info

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  1. TA Info • Francis (Frank) Iosue • • Office = 192 Mendel • Monday 9-10 AM • Tuesday 9-10 AM • By Appointment

  2. Attendance • 260 points (37%) of your grade for the course will be based on lab • Attendance is MANDATORY – NO Make-up labs • If you have a legitimate reason to miss lab, contact me or Ms. Jamison Immediately • 2 Field Trips

  3. Academic Integrity • Policy set forth in the “Blue Book” will be strictly enforced • Unless specifically stated, all assignments are to be done alone! • If you are unsure, ASK ME!

  4. Safety • No food or drink • Appropriate dress (no open-toe shoes, long pants, no halter tops) • NO CELL PHONES!!! • Leave the lab clean • Safety goggles and gloves when needed.

  5. Plants & CivilizationBIO 1785 Lab #1: The Microscope & Plant Cells

  6. The Microscope…A Review Compound Light Microscope – useful for viewing slides vs. Dissecting Microscope – useful for viewing 3-D images. ALWAYS HANDLE THESE EXPENSIVE PIECES OF LAB EQUIPMENT WITH EXTREME CARE!

  7. Compound Light Microscope Identifying the parts of a microscope Know where parts are located & what each is used for. TA will demonstrate proper use if you don’t remember! Always ask if unsure so that you do not damage the scope!

  8. Compound Light Microscope Recall… • Total Magnification = objective lens (listed on objective) x ocular lens (10x). • Field of View: what you see when you look through the eyepiece. • How does this field change when switching to higher magnification? • Depth of Field: thickness of the object in focus. • Are all layers of your specimen in focus at the same time? If not, what does that indicate?

  9. Solid Specimen (e.g. potato) Drop of H2O onto slide Very thin slice of potato onto drop Liquid Specimen (e.g. Oscillatoria) Use pipet to “mix up” specimen, then draw up Place one drop of specimen onto slide How to Make a Wet-Mount Preparation TA will DEMONSTRATE Onion wet-mount….

  10. FOCUSING on your wet-mount …“I can’t see anything on my slide!” -first time scope user • First, fit slide securely into stage clip. • With scanning power objective lens (4x) in place, adjust the stage upward using the coarse adjustment knob so that the lens is almost touching the slide –DO NOT allow the lens to hit the slide & DO NOT LOOK THROUGH THE EYEPIECE YET! (you should be looking from the side) 3. Now, while looking through the eyepiece, use coarse focus knob to “focus downward” on your specimen. [Focusing “upward”, that is moving the stage upward toward the objective lens, may result in breaking your slide & damaging the objective lens – never do this]. ALWAYS, ALWAYS, ALWAYS – FOCUS DOWNWARD!

  11. Part II: PLANT CELLS CELLS are the basic unit of life. All plants are comprised of cells. Prokaryotes vs. Eukaryotes Prokaryotes: cells which do NOT contain a membrane-bound nucleus or other organelles. Instead, prokaryotes have a plasma membrane only. Examples: bacteria & cyanobacteria.

  12. PROKARYOTES[The Cyanobacteria] Largest prokaryotes = CYANOBACTERIA [a.k.a. “blue-green algae”] • Cyanobacteria contain chlorophyll a & other pigments (phycobilins) needed for photosynthesis. • Pigments are NOT contained in chloroplasts, but in photosynthetic membranes called thylakoids. • Perform photosynthesis similar to eukaryotic plants • Important 10 producers (both on land in aquatic ecosystems). • Do they produce their own food??? YES!!

  13. Examine Cyanobacteria Prepare wet-mounts of & examine (sketch): • Oscillatoria – filamentous w/ rhythmic mov’t • Nostoc – filamentous w/ cell differentiation (heterocysts) • Anabaena – filamentous w/ heterocysts • Gloeocapsa – heavy gelatinous sheath holding uni-cells together • Cylindrospermum – filamentous with heterocysts & akinetes

  14. Cyanobacteria… what can they do? • Capable of photosyntheis - O2 evolving • Heterocysts - N2 fixation (enriches aquatic environments) • Akinetes – provide survival support Heterocyst Akinete Vegetative filament

  15. BACTERIA • Are prokaryotes • Not the same as cyanobacteria! • How does the size of a bacterial cell compare to that of cyanobacteria? For answer: Compare your observations of cyanobacteria to DEMOs of bacterial cells.

  16. EURKARYOTES – Plant Cells • Eukaryotes: cells which do contain a membrane-bound nucleus & other organelles. The cytoplasm is contained within the plasma membrane. • Chloroplasts = green organelles which contain chlorophyll. This is the site of photosynthesis in plant cells. • Another organelle = mitochondria where cellular respiration occurs.

  17. Eukaryotes- Plant Cells (con’d) Structure of Plant Cells Note: cuboidal shape & numerous organelles

  18. Specialized Plant Cells & Tissues Types by Function: • Support • Collenchyma, Sclerenchyma (includ. Sclerids) • Vascular • Xylem, Phloem • Storage, etc. • Parenchyma • Protection • Epidermis, Cork, Cork Cambium

  19. Specialized Plant Cells & Tissues SUPPORT: • Collenchyma cells– provide mechanical support w/ irregularly thickened cell walls esp. while cells are growing. • Thickened at corners; Cells just beneath epidermis; reddish in color & appear ‘star or hexagon-shaped’ under scope. • Sclerenchyma fibers– long & slender support occuring in bundles w/ heavy 2o cell walls made of lignin. • Strong polymer; rigid support; If cell dies lignin can still provide support; also appears reddish in color. • Sclerids: type of sclerenchyma cell variable in shape for strength & rigidity, often branched & ‘gritty’ in appearance. • Provides heavy 2o cell wall support • Lignified (so it appears pink/reddish) • Connects two air spaces • Example: Stellate sclerid – named due to shape.

  20. Collenchyma Sclerenchyma Examples of: Support Cells & Tissues Sclerids

  21. Specialized Plant Cells & Tissues Vascular: • Xylem cells- modified elongated cells that conduct H2O by capillary action. • Xylem vessel elements (1 cell) align end-to-end forming xylem vessels. • Lignified 2o walls, thickened in various patterns(e.g. annular, reticulate, sclariform). • Xylem rings are deposited yearly – used to age a tree! • Phloem cells- modified cells for transport of organic solutions. • Consist of sieve tube members & companion cells. • At maturity, differentiated for conducting materials, loses nucleus, but remains fully functional.

  22. Xylem & Phloem, c.s. Examples of: Vascular Cells & Tissues A = Phloem(green cells) B= Xylem(red cells)

  23. Xylem: A Closer Look Longitudinal sections: note patterns of lignified cell walls Anatomy-stems,seeds,embryos/Xylem%20fibers%20&%20vessels%20l.s..jpg

  24. Phloem: A Closer Look Longitudinal section: showing sieve tube members with “sieve-like” end wall & associated companion cells. Cross section: showing green phloem cells in a vascular bundle w/ xylem.

  25. Specialized Plant Cells & Tissues Storage, etc. • Parenchyma cells – thin-walled living cells that are most abundant cell type in plants. • Many kinds of parenchyma cells that perform diverse functions including: • Photosynthesis (in leaves) • Intercellular communication • *Food (starch) storage (in roots & stem of plant)

  26. Parenchyma Cells Cross section: showing cellular inclusions. What are these inclusions & what do they tell you about the function of this type of parenchyma??? Plant stem – parenchyma cells make up the cortex

  27. Specialized Plant Cells & Tissues Protection: • Epidermis – outermost layer of cells of leaf, stem, & roots exposed to environmental stresses. • Covered by cuticle (waxy layer) -prevents H2O loss • Where guard cells & subsidiary cells are found around stomata openings. -regulate CO2 in & O2 out of plant cells • Periderm – consists of Cork & Cork Cambium which replaces epidermal tissue that is worn away by environmetal wear & developmental/mechanical stresses.

  28. Epidermis Outermost layer of cells = epidermis Guard cells surrounding stomata opening (within epidermal layer) Trichomes = extensions of epidermis

  29. Cork & Cork Cambium Found in roots & stems. • Cork cambium cells undergo active mitotic division, then migrate to the • outside to form cork. • Cork cells form waxy material called suberin which provides protection, • but seals cork off from other cells of the plant. Cork cells are still • functional even when dead.

  30. Part I - Microscope Refresher Course Lab Manual pp. 1-20 Label parts of microscope & recall proper usage (proper focusing technique, field of view, depth of view, magnification). Making wet-mounts of potato, onion…for practice. Study wet-mounts of cyanobacteria in part 2. Part II – Specialized Plant Cells & Tissues Lab Manual pp. 21-42 Prokaryotes Cyanobacteia wet-mounts & sketches (label diagrams!) Bacteria types DEMO slide vs. Eukaryotes Plant cell general structure Elodea wet-mount Specialized Cells & Tissues Support, Vascular, Storage & Protective types View various slides of each, sketch, & label. TODAY’S PLAN:Summary