GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Imaging Techniques
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
Example Questions
Example Question #1 :Laboratory Practices
下列哪一项技术是最我们吗eful for a researcher who is trying to determine the structure of a protein?
X-ray crystallography
LCMS
Equilibrium centrifugation
FPLC
X-ray crystallography
X-ray crystallography is a very powerful technique used to determine the structure of proteins. It involves first obtaining a crystal of your protein and then shooting x-rays through the sample and observing the resulting diffraction pattern.
Equilibrium centrifugation is a separation technique. FPLC is used to purify proteins. LCMS is used to analyze large samples of peptides quickly.
Example Question #2 :Laboratory Practices
What does a microarray allow you to visualize?
The base pair sequence of a gene
The genome size of an organism
Expression levels of multiple genes
All of these
The level of cellular replication in a sample
Expression levels of multiple genes
A microarray is a chip with many copies of short segments of DNA that allows you to visualize the expression level of potentially unlimited genes simultaneously. It only informs you on how many copies of the gene are present in a sample, and does not give any information on gene sequence/length, etc.
Example Question #1 :Help With Imaging Techniques
Which type of microscopy is needed to study subcellular structures like organelles?
Scanning electron microscopy
Light microscopy
Transmission electron microscopy
Both light microscopy and scanning electron microscopy
Both scanning and transmission electron microscopy
Both scanning and transmission electron microscopy
Light microscopy can magnify a sample up to 1000X. this is not enough to visualize subcellular structures like organelles in cells. Electron microscopy can magnify a sample much higher than 1000X and so can be used to visualize subcellular structures. Both scanning and transmission electron microscopy magnify to this extent.
Example Question #4 :Laboratory Practices
What type of microscopy would you use if you want to get a topographical/3D image of your sample?
Scanning electron microscopy
Fluorescence microscopy
Transmission electron microscopy
Light Microscopy
Both scanning and transmission electron microscopy
Scanning electron microscopy
Scanning electron microscopy runs a beam of electrons over the surface of a specimen. This beam changes in length as the specimen changes in height off the slide. The microscope can detect the change in beam length and generate a 3D image of the specimen. All of the other forms of microscopy listed produce 2D images.
Example Question #1 :Help With Imaging Techniques
Which of the following is true concerning light microscopy?
It uses a light source and a glass lens to magnify images
It provides greater resolution than an electron microscope
It works via a magnetic force that depends on electron concentration
It can produce three dimensional images of living material
It can only be performed on living material
It uses a light source and a glass lens to magnify images
Light microscopy uses light and a glass lens to magnify images. The higher the magnification, the more blurry the image. Special staining techniques are used to produce images via light microscopy. Electrons are not utilized in light microscopy.
Example Question #1 :Laboratory Practices
Light microscopy and electron microscopy are used for the same purpose: to magnify very small objects for further examination by using radiation. The fundamental difference is that light microscopes use radiation of visible light, and electron microscopes use radiation of electron beams. This technical difference impart different properties on each type of microscopy. Each of the following describes a difference between light and electron microscopy, except__________.
"electron microscopy permits much higher magnification than light microscopy."
"electron microscopy has a much higher resolution than light microscopy."
"usage of a vacuum tube is required in electron microscopy to prevent electrons from escaping."
"light microscopy requires only a tungsten coil to produce a light beam, while electron microscopy couples a tungsten coil and magnetic lenses to produce and focus the electron beam."
"light microscopy specimens can be alive because they do not need to be dehydrated, as is the case with electron microscopy."
"light microscopy requires only a tungsten coil to produce a light beam, while electron microscopy couples a tungsten coil and magnetic lenses to produce and focus the electron beam."
Light microscopy does not need a tungsten coil to produce visible light, only a strong but simple light source is required. Electron microscopy does employ a tungsten coil and magnets for this purpose. Each other answer choice describes a difference between the two types of microscopy.
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All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
