Name ___________________________________________ Date _________________
AP Biology Lab:
Cells and Organelles Under the Microscope
Overview
At this point, our ability to understand the internal structure of cells far exceeds the ability of the ordinary
light microscope to reveal such complex structures. For this reason, this is a primarily computer-based
lab, with a chance to use an actual microscope at the end.
To get started, download a digital copy of this lab packet from the AP Bio blog:
http://phascience.wordpress.com/ap-biology-dickson/
Follow along with the digital version so that you can just ctrl-click each link to get to the images.
Part A: Prokaryotic vs. Eukaryotic Cells
Links to examine:
Prokaryotic Cell: http://dtc.pima.edu/blc/182/lesson4/prokaryotes/prokaryoteimages/bacteriumcolor2.gif
Eukaryotic Human Cell (pancreas): http://library.thinkquest.org/3564/gallery.html - scroll down and click
on the very bottom image
1. Use the microscope images in the links above to draw side-by-side sketches of a typical prokaryotic
and a typical animal cell.
 Label (on both) the DNA, ribosomes, and plasma membrane.
 Label at least 2 other organelles in your eukaryotic cell diagram.
2. While prokaryotic and eukaryotic cells both have DNA and ribosomes, there are some key differences
between the DNA and ribosomes in each cell type. Complete the chart below to compare and
contrast these essential genetic structures in prokaryotes and eukaryotes. (Use the links below as well
as your textbook!)
Ribosomes: Prokaryotic vs. Eukaryotic:
http://www.chem.ox.ac.uk/vrchemistry/LivingCells/HTML/page10.htm
The dark dots in the micrograph are ribosomes.
What do you think the wiggly strings coming out of the ribosomes are?
Look carefully and see one string that is running vertically down the micrograph that all the
ribosomes are attached to. What do you think this is?
Now use the information on this website, plus information in your textbook, to complete the chart
below.
DNA
Similarities
Prokaryotes
Eukaryotes
Ribosomes
Similarities
Prokaryotes
Eukaryotes
Part B: The Nucleus
Links to examine:
Various images of the surface and interior of the nucleus:
(a) A nucleus in situ after fracturing and (b) in further detail (whole nucleus) and (c) the
cytoplasmic surface of the nucleus showing nuclear pore complexes. (d) Shows a fracture
which has traveled through the cell close to the substratum, exposing the nuclear interior,
nuclear contents can be seen as differentially condensed chromatin fibers which attach to
the inner aspect of the nuclear envelope. Panels (e) and (f) show fractures through the
upper aspect of the nucleus, exposing nuclear content such as nucleoli (no) and peripheral
chromatin (pc). In (a) and (d) scale bar = 10 mm, in (c) and (f) scale bar = 300 nm.
http://www.nature.com/nprot/journal/v2/n5/fig_tab/nprot.2007.139_F1.html
Transmission Electron Micrograph (TEM) of a nucleus:
http://online-media.uni-marburg.de/histologie/introhis/HIS/txt/tacsem/tac01_sem.htm
Freeze-fracture TEM of a mouse pancreas cell with nucleus and nuclear pores clearly visible:
http://www.stolaf.edu/people/giannini/cell/nuc/em7b.gif
3. Based on the images in the links above, draw and label a sketch of a eukaryotic cell nucleus.
Annotate your drawing with notes about the functions of the following:
 nuclear membrane (aka nuclear envelope)
 nuclear pores
 nucleolus
 chromatin
Part C: The Endomembrane System
Links to examine:
Rough and smooth ER in a liver cell:
http://www.zoology.ubc.ca/~berger/b200sample/unit_8_protein_processing/images_unit8/0_300_er.jpg
Golgi: http://synapses.clm.utexas.edu/atlas/1_1_3_1.stm
4. Diagram and describe the structure and function of the rough ER, smooth ER, and Golgi apparatus.
What do they have in common, and how do they differ? Be sure to mention the structures and
functions of each.
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Follow this link to the AP Bio blog, where you should find a Powerpoint file titled “Day in the Life of a
Cell.” Open it, start the presentation, and click through to follow the making and transport of a protein
(this may look familiar from 9th grade…)
http://phascience.wordpress.com/ap-biology-dickson/
5. Cells often produce secretory proteins that are exported from the cell.
a) Trace a secretory protein from its origin at a ribosome to its release outside the cell. Be sure to
describe the structure and function of each organelle that is involved in making, transporting, and
modifying secretory proteins.
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b) Pancreatic cells (like the one in the micrograph shown here:
http://library.thinkquest.org/3564/gallery.html - scroll down and click on the very bottom image)
often have a high density of rough endoplasmic reticulum and Golgi complex, as do cells in the
salivary glands. Why?
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Part D: Mitochondria and Chloroplasts
Links to examine:
Go to http://library.thinkquest.org/3564/gallery.html and find the following pictures. Read the
descriptions, then click on each image to see it in more detail:
 Chlamydomonas cell
 Corn plant cell
 Mitochondrion
 Chloroplast
6. Compare and contrast the structure and function of mitochondria and chloroplasts.
a) Draw labeled sketches of each organelle.
b) How are the structures of these two organelles similar, and how are they different? (We will
consider their functions in much greater depth in later chapters.)
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c) A common misconception is the following: Only plant cells contain chloroplasts and only animal
cells contain mitochondria. Which part of this statement is false? Rewrite it correctly. Explain
how it relates to the major difference in the way that plants and animals acquire food, and the
major similarity in the way they convert food into usable energy.
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Part E: Other Membrane-Bound Organelles
Go back to the image of the corn plant cell:
http://library.thinkquest.org/3564/gallery.html
7. What is the huge white organelle? What is its function? Draw a quick sketch:
8. Go to http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cell&part=A6152 and skim the first 2
sections, then look at Figure 22-25.
What is the function of the cells in this figure, and why do they have so many lysosomes?
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Part F: Cytoskeleton!
Do a Google Image search for “cytoskeleton” and find some pretty pictures (focus on the micrographs
rather than the cartoon diagrams). Sketch one here (and cite where you got the image from)
Next, go to (copy and paste this whole link into your browser)
http://www.exploratorium.edu/imaging_station/gallery.php?Asset=Human white blood cell phagocytosis&Group=&Category=Cell Motility&Section=Introduction
1. Read the short blurb at the top of the website.
2. Watch the video of white blood cells engulfing green invaders.
3. Then watch the “crawling amoeba” video on the same site.
9. What are two functions of the cytoskeleton?
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Part G: Use a Real Microscope Yourself! (Optional)
Check out…
 Living plant cells under the microscope (look for chloroplasts and if you’re lucky, cytoplasmic
streaming)
 Your own check cells
 Prepared slides from the boxes
Sketch and label what you see, here:
Other Questions
10. Many people confuse the plasma (cell) membrane and the cell wall.
a) Explain the major differences in structure and function between the plasma membrane and the
cell wall. Which of these two structures is found in all cells, and why?
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b) Cell walls have evolved independently in several different domains and kingdoms. Briefly
identify the main differences in the cell walls of plants, fungi, and eubacteria.
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11. After very small viruses infect a plant cell by crossing its membrane, the viruses often spread rapidly
throughout the entire plant without crossing additional membranes. Explain how this occurs.