For Ensemble Students

1
For Ensemble Students

• Images from the Labs You Missed
• Cell Structure Part I
• Cell Structure Part II
• Diffusion and Osmosis
• Many of these images were retrieved from the
  Internet, thanks to all of the original
  contributors of these images. I have attempted to
  cite the original source of each image. This
  should really help my students catch up. Thanks
  again.

2
After adding salt solution(For cells and osmosis
lab)
Picture and description from http//waynesword.pa
lomar.edu/lmexer1.htm
3
Explanation of how Plasmolysis works

• Elodea leaf cell illustration from a microscope
  slide. A drop of 10 percent NaCl (sodium
  chloride) solution was added to the slide. Left
  The cell membrane has pulled away from the cell
  wall marking the onset of plasmolysis called
  "incipient plasmolysis." Right The entire cell
  contents (protoplast) within the membrane has
  shrunk into a blob in the center of the cell.
  This phenomenon is called plasmolysis. Salt ions
  (Na and Cl-) have passed through pores in the
  cellulose cell wall. The ions do not pass through
  the protein-lipid cell membrane because it is
  impermeable to them. Due to the concentration
  differential inside and outside of the membrane,
  water molecules (shown by blue arrows) move out
  of the cell membrane, thus causing the cell
  contents to shrink into a blob. This
  concentration differential does not occur outside
  the porous, rigid cell wall, therefore its
  rectangular shape remains intact.

4
Elodea image for Lab 2
Image and explanation retrieved
fromhttp//waynesword.palomar.edu/lmexer1.htm
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Important Info On Elodea

• Waterweed (Elodea densa) a submersed South
  American aquarium plant that is naturalized in
  ponds, streams and lakes throughout North
  America. It belongs to the frog's-bit family
  (Hydrocharitaceae) along with the troublesome Old
  World aquatic weed called hydrilla (Hydrilla
  verticillata) that literally clogs the waterways
  of canals and reservoirs. The highly magnified
  view of a leaf (right) shows a living
  photosynthetic cell. Because most of the cell is
  occupied by a water-filled, large central
  vacuole, the chloroplasts are displaced around
  the periphery of the cell, just inside the cell
  wall and membrane. The chloroplast shown by top
  red arrow is actually on the outside of this
  vacuole. Due to the limited depth of field at
  this magnification (400x), only portions of the
  viewing plane are in focus at any one time. To
  see additional chloroplasts you must focus up and
  down with the fine adjustment knob of the
  compound microscope. The transparent nucleus is
  not visible in this image.

6
Onion Image for Lab 2
Image and explanation retrieved
fromhttp//waynesword.palomar.edu/lmexer1.htm
For our purposes you only need the image on the
left, see next slide for further information.
7
Potato Image for Lab 2
Starch is typically stored in underground organs,
including storage roots, rhizomes, tubers, corms
and bulbs. Magnified view (400x) of several
parenchyma cells of a potato tuber showing the
thin, transparent cell walls and clusters of
amyloplasts (starch grains). The starch grains
were stained black with gram's iodine.
8
Onion Slide for Lab 2

• Left Microscopic view of an onion skin showing
  several rectangular cells, each with a small,
  spherical nucleus (red arrow). The slide was
  stained with a drop of yellowish-brown gram's
  iodine.
• Right Highly magnified view of a cell from the
  meristematic root tip of an onion showing
  enlarged nucleus containing 16 chromosomes. The
  cell is in prophase of mitosis, with distinct
  chromosomes (chromosome doublets) and a
  disintegrating nuclear membrane.

9
Cheek Cells for Lab 1
These cheek cells were stained with methylene
blue, while ours were stained with iodine which
made them appear yellow. The purpose of staining,
though was the same, to be able to see
transparent structures clearly. Image and
description retrieved from http//waynesword.palo
mar.edu/lmexer1.htmcheek
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Explanation of Cheek Cell Image

• Magnified view (400x) of squamous epithelial
  cells from the buccal mucosa (cheek cells from
  inside the mouth). The cells are stained with a
  dye called methylene blue. The nucleus and cell
  membrane are clearly visible. Plant structures
  such as a cell wall, chloroplasts and large
  central vacuole are absent. Because they don't
  have a rigid (firm) cellulose cell wall, these
  cells are flimsy and irregular in shape, unlike
  the rectangular shape of the onion cells.

11
Blood Image
Image retrieved from http//image.bloodline.net/s
tories/storyReader1513
12
Bacteria Images from Lab 1
Bacteria under high power magnification, please
note that this is a view of many different types
of bacteria on the same slide. See explanation on
next page.
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Explanation of Bacteria seen in Lab 1

• PROKARYOTESThe pictures below are from bacteria
  observed in lab. The picture on the left is of
  mixed bacteria while the one on the right is from
  yogurt. Bacteria represent the most simple cell
  structure and these are generally considered to
  be the most "primitive" of organisms. Look
  closely at the picture on the left and you should
  see the three different shapes of bacteria (1)
  cocci (spheres), (2) bacilli (rods), and (3)
  spirilli (spirals). Did you know that many types
  of spirilli actually function like a cork screw
  and bore into humans or animals and cause
  infection? Many types of cocci and bacilli cause
  infection as well. Look closely at the yogurt
  picture (on the right) and you'll see the milk
  portion (clumpy, whitish material) and the
  "living culture" portion (small rod-shaped cells
  which are actually bacteria). Questions to
  consider1. Do these organisms have a
  nucleus?2. In general, are these cells larger or
  smaller than eukaryotic cells?3. Are these cells
  prokaryotic or eukaryotic?
• Retrieved from http//www.und.nodak.edu/dept/jca
  rmich/101lab/lab2/lab2.html

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Cork cells high power from Lab 1
Image retrievedfromhttp//www.biology.clc.uc.edu/
Fankhauser/Labs/Cell_Biology/Cells_Lab/cork_100x_P
A021953c.JPG
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Diffusion

• See the attached powerpoint for a more detailed
  explanation Diffusion Ppt
• We are only doing the part with the bag and the
  starch, not the glucose portion

Images retrieved from http//www.shelterisland.k1
2.ny.us/science/Biology/Diffusion.ppt10
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In class we made a model cell membrane using a
sandwich bag. We added starch to the Tube. We
then placed the tube into a beaker filled with
water and starch indicator (Iodine). The Starch
indicator (Iodine) made the water turn Amber
color.
The Cell
Water is Amber due to Iodine
Filled with Starch
17
Answer the following Question
3. Based on your knowledge of diffusion, predict
what will happen to the substances inside and
outside of the "cell'' Record your prediction on
your lab sheet.
18
If, the Iodine mixes with starch it will turn
blue black.
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We let the beaker sit for a few minutes. Now,
carefully examine the cell and beaker
below. Record any changes including color changes
you observe in the cell and the beaker.
The Cell
Water is Amber due to Iodine
Filled with Starch
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Make sure you have done the following
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Schedule