TA Info

1
TA Info

• Francis (Frank) Iosue
• Francis.iosue_at_villanova.edu
• Office 192 Mendel
• Monday 9-10 AM
• Tuesday 9-10 AM
• By Appointment

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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 MicroscopeA 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 dont
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.
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FOCUSING on your wet-mount

• I cant 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!

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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.
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PROKARYOTESThe 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 movt
• Nostoc filamentous w/ cell differentiation
  (heterocysts)
• Anabaena filamentous w/ heterocysts
• Gloeocapsa heavy gelatinous sheath holding
  uni-cells together
• Cylindrospermum filamentous with heterocysts
  akinetes

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Cyanobacteria what can they do?

• Capable of photosyntheis - O2 evolving
• Heterocysts - N2 fixation (enriches aquatic
  environments)
• Akinetes provide survival support

Heterocyst Akinete Vegetative filament
http//www.dr-ralf-wagner.de/Bilder/Cylindrospermu
m.jpg
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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.

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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 (cond)

• 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

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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.

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Examples of Support Cells Tissues

• Collenchyma

• Sclerenchyma

Sclerids
http//www.rhodes.edu/biology/stinemetz/sclerid1.j
pg
http//www.vet.purdue.edu/bms/intl/nourpix/an0020.
jpg
http//www.sc.chula.ac.th/courseware/2303105/spec/
03.JPG
http//www.nsci.plu.edu/jmain/b359web/images/scle
rid(2TN).jpg
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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.

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Examples of Vascular Cells Tissues

• Xylem Phloem, c.s.

A Phloem (green cells) B Xylem (red cells)
http//www.life.uiuc.edu/ib/202/labs/structure/pla
nt_transpiration/buttercup400x.jpg
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Xylem A Closer Look
Longitudinal sections note patterns of lignified
cell walls
http//www.skidmore.edu/academics/biology/plant_bi
o/ Anatomy-stems,seeds,embryos/Xylem20fibers20
20vessels20l.s..jpg
http//www.rothamsted.bbsrc.ac.uk/notebook/courses
/guide/images/xilem.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.
http//www.bbc.co.uk/scotland/education/bitesize/s
tandard/img/biology/structure_phloem.gif
http//botit.botany.wisc.edu/images/130/Stem/Zea_c
ross_section/Phloem.low.jpg
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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)

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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
http//members.tripod.com/ashley_tan/histology/ima
ges/plant_histology-root_dicot_ts.jpg
http//members.tripod.com/ashley_tan/histology/ima
ges/plant_histology-basic_tissues_parenchyma_ts.jp
g
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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.

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Epidermis
http//images.botany.org/set-13/13-021v.jpg
Outermost layer of cells epidermis
Guard cells surrounding stomata opening (within
epidermal layer)
Trichomes extensions of epidermis
http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
92462b.jpg
http//bugs.bio.usyd.edu.au/2003APmodules/graphic
s/A62a.jpeg
29
Cork Cork Cambium
Found in roots stems.
http//www.botany.hawaii.edu/faculty/webb/BOT201/P
rimSec/Peri-2240Lab.jpg

• 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.

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TODAYS PLANSummary

• 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, onionfor 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.