1. TA Info Francis (Frank) Iosue Francis.iosue@villanova.edu
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 & Civilization BIO 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. How to Make a Wet-Mount Preparation
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
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. Prokaryotes vs. Eukaryotes
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. Examples of: Support Cells & Tissues
Collenchyma
Sclerenchyma
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. Examples of: Vascular Cells & Tissues
Xylem & Phloem, c.s.
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
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. TODAY’S PLAN: Summary 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
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.