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Cell Bio Lecture 3
Cell Bio Midterm 1
| What is cell fractionation used for? | Lyses cells and separates organelles by size and density. |
| What is velocity sedimentation used for? | Achieves a finer degree of separation and organizes cell components by size and shape. |
| What is equilibrium sedimentation used for? | Achieves a finer degree of separation and organizes cell components by density. |
| What is chromatography used for? | Proteins can be separated based on their properties (eg. charge, size, hydrophobicity, ability to bind small molecules). |
| Which type of chromatography is the method of choice for smaller molecules/proteins? | HPLC |
| What is SDS-PAGE used for? | Proteins migrate through a gel polyacrylamide matrix at a rate depending on charge, size, and shape; useful for membrane (hydrophobic) proteins; provides information about molecular weight and subunit composition. |
| What is mass spectrometry used for? | Useful in identifying unknown proteins by mass/charge ratio; give an idea for the end protein amino acid sequence. |
| What is a yeast two-hybrid system used for? | Useful in detecting protein-protein interactions using bait/prey resulting in transcription. |
| What is FRET/GFP used for? | To see protein interactions/where in a cell a protein is located through labeling molecules with fluorochromes and seeing where fluorescence occurs. |
| What us X-Ray crystallography used for? | It gives the 3D structure of proteins (provided that the protein can form crystals); usually used for larger proteins. |
| What is NMR used for? | It gives the 3D structure of proteins without the need for a crystal; usually used for smaller molecules. |
| What is a Southern blot used for? | Allows for the detection of a specific DNA sequence via probe hybridization; gives information about identity, size, and abundance. |
| What is PCR used for? | Amplification of DNA; useful if the genome sequence is known. |
| What are expression vectors used for? | Sequence of DNA is inserted into a vector (plasmid) and cloned for virtually unlimited amounts of protein expression. |
| What is RNA interference (RNAi) used for? | Useful in figuring out what a gene does via knockout and degradation of specific mRNAs and viewing the consequences in a living organism. |
| What are microarrays used for? | Allow for simultaneous analysis of thousands of RNAs through use of probes which bond to mRNA and monitor expression; probe sequences must be known in advance. Can compare genes under different environmental conditions. |
| Bacteria and mitochondria are generally the smallest objects which can be seen with a _____ microscope. | light |
| _____ light microscopy allows for the visualization of density/cell structure. | phase-contrast |
| _____ light microscopy takes advantage of light scattering as it passes through a specimen. | dark-field |
| Define selective staining. | Sections can be stained with dyes which have affinity for specific cellular components - hematoxylin has affinity for - charge molecules, eosin has affinity for + charge molecules. |
| What is in situ hybridization used for? | Visualization of the distribution of RNAs in a sample of tissue with fluorescently labeled probes. |
| Describe fluorescence microscopy. | Molecules are labeled with fluorescent markers which absorb one wavelength of light and emit another. It is used to detect specific proteins/molecules in the cell. |
| Define fluorescent nanoparticles. | Fluorochromes which are more stable and fade less quickly than traditional methods; ie. quantum dots. |
| How are antibodies utilized in microscopy? | Antibodies are labeled with fluorescent dyes; the antibody combines with an antigen and allows for location of molecules in the cell. |
| Describe confocal microscopy. | Pin-point illumination of a single point in a specimen. Eg. seeing where are virus goes. |
| T or F: Electron microscopes give lower resolution than light microscopes. | False |
| Describe electron microscopy. | Specimens are stained and put through an electron beam/vacuum; gives fine cellular structure. |
| T or F: Immunogold microscopy is analogous to antibody detection with fluorescent microscopy. | True |
| What is one pro and one con to immunogold microscopy? | Allows to locate multiple proteins in one sample, but can only detect antigens at the surface of the section. |
| T or F: Scanning electron microscopy can only produce 3D structure on the surface of the specimen. | True |
| What is scanning electron microscopy typically used for? | Visualization of whole cells/tissues. |
| Describe electron microscope tomography. | Allows for the specimen to be tilted and viewed from different angles in order to perceive depth; 3D images are combined and taken at the average. |
| What are the advantages of GFP? | GFP can be produced by the cell. Cells are dynamic so it is possible to visualize movement of molecules in the cell; moniters gene expression. |
| What are fluorescent indicators used for? | Allow for the measurement of concentration of a substance in the cell (eg. Ca) at different locations by binding to the molecule of interest. |
| What are five different methods of getting substances into cells? | Micropipette injection, electroporation, lipid fusion, DEAE dextran, biolistics |
Created by:
goberoi
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