Chapter two kerboodle Flashcards
A structure within cells consisting of microtubules and microfilaments
Cytoskeleton
b A graduated measuring scale placed on the microscope stage.
(Stage) micrometer ü
The two parts of a light microscope that magnify the specimen
Eyepiece lens ü Objective lens ü
The dark-staining region of a cell where ribosomes are made
Nucleolus ü
The detailed structure of cells visible only with an electron microscope
Ultrastructure ü
Describe one difference between: a eukaryotic and prokaryotic cells
Prokaryotic versus eukaryotic: ü ü No nucleus vs. have nucleus / No membrane-bound organelles vs. have membrane-bound organelles / No histones vs. have histones / Circular DNA vs. linear DNA / Size < 1 µm vs. size > 10 µm
light microscope and electron microscope imaging advantages
Light versus electron: ü ü Can see live cells vs. cells must be fixed (dead) / Can show biochemistry by staining vs. can only show difference in electron density / Quick specimen preparation vs. time-consuming / Fewer artefacts vs. tissue damage by electron beam / Smaller magnification vs. greater magnification / Poorer resolution vs. better resolution /
magnification and resolution.
Magnification versus resolution: Magnification is how much bigger image is compared to object ü vs. resolution is ability to distinguish two close points as separate / to see finer level of detail ü
a Explain why: i methylene blue was added
To stain cell / provide contrast / show nucleus ü
ii the cover slip was lowered gently
To avoid trapping air bubbles ü
iii the microscope was set to its lowest magnification.
To see largest area of slide / to focus more easily using coarse focus ü
No cells were visible at the lowest magnification. Describe how the student can achieve a good focus on low power before looking for cells at a higher magnification.
Place the edge of the cover slip in the middle of the stage and adjust focus until the edge is sharp and clear ü
The student had eaten cereal and not cleaned her teeth before making her cheek cell slide. Plaque bacteria and pieces of fibrous plant material were visible on the slide. Suggest how the bacterial and plant cells could be distinguished from the cheek cells.
Bacteria very small / only visible at high power / grouped in clusters ü Plant cells angular or rigid in shape (due to / ref. cell walls) ü
Name the microscope most suited to gaining a 3D view of a specimen emitting fluorescence as a result of having bound to labelled antibodies
Laser scanning confocal microscope ü
In an experiment, a ciliated protoctist was exposed to fluorescent antibodies specific to the protein tubulin. Describe the pattern of fluorescence you would expect to see.
Ref. to network of microtubules / cytoskeleton ü Ref. to positions of cilia on cell surface membrane
