Char Chap 4 Flashcards
How long is a paramecium?
.33 millimeters
How does a light microscope work?
Visible light is passed through the specimen and then through glass lenses that magnify the image
What is resolution?
Resolution is the ability to distinguish to nearby objects as separate.
What is the maximum effective magnification through a light microscope?
1000 times out of
The human eye can distinguish points as close together as
0.1 mm
At typical light microscope can see details at about
0.2 micrometers (um)
Get comfortable with all the numbers.
1000 nm makes one micrometer 1000 µm makes 1 mm
10 mm makes 1 cm
100 cm makes 1 m
What size of biological structure can the electron microscope see?
2 nm. This is a 100 fold improvement over the light microscope.
How does the scanning electron microscope work?
The scanning electron microscope uses an electron beam to scan the surface of a cell or other sample, which is usually coded with a thin film of gold.
What is the transmission electron microscope used for?
It is used for studying the details of internal cell structure. The TEM aims an electron beam through a small section of the specimen which has been stained with atoms of heavy metals.
How is Light microscopy superior to electron microscopy?
With a light microscope, you can watch the movement of cells, and this is not possible with electron microscopy because EM will kill the cells.
Why are cells so small?
Cells need to have a large surface to volume ratio. This allows for a large amount of traffic across their cell membranes to get things in and out of the cell itself.
The cell membrane is made of a phospholipid bilayer. How was the phospholipid bilayer created?
Each phospholipid is composed of two distinct region a head with a negatively charged phosphate group and two nonpolar fatty acid tails. They line up with hydrophobic ends pointing inward, hydrophilic heads pointing outward.
What is the difference between a prokaryotic cell and a eukaryotic cell?
Prokaryotic cells evolved first. Eukaryotic cells are distinguished by having a membrane-enclosed nucleus, which holds most of their DNA, and also have many membrane enclosed organelles. Prokaryotic cells are simpler.
What is the “nucleoid” area of the cell?
The “nucleoid” is only in prokaryotic cells—it is the area where the dna is located in the cell but it is not enclosed by a membrane.
