topic a: how cells are studied

• phase contrast light microscopy casts a halo on the specimen
• DIC light microscopy casts a shadow on the specimen
• widefield fluorescence microscopy uses fluorescent molecules to label cells and tissues
• confocal fluoresence microscopy shows a 2D section of a 3D specimen
• tomography shows a 3D model of a specimen
• coloured stains have an affinity for certain substances and can absorb light
• fluorescent stains have an affinity for certain substances and fluoresces light
• DAPI has an affinity for DNA
• fluorescent probes are covalently bonded and can be used to detect a specific thing
• antibodies are proteins that are produced by white blood cells that bind to antigens
• transmission electron microscopes pass electrons through a specimen
• scanning electron microscopes bounce electrons off the specimen and form an image
• SEM specimen are coated in gold in order to enhance contrast and allow for magnification
• TEM can produce 3D images
• negative staining highlights a specimen against its background
• shadowing is when a specimen is coated in metal atoms at a specific angle and then placed in a magnetic field
• ultrathin sectioning allows a specimen to be cut into very thin pieces
• subcellular fractionation allows scientistst to isolate and purify oranganelles using centrifugation
• homogenization is the process of breaking the plasma membranes to release contents
• cells can be broken with high frequency sound
• detergents can be used to make holes in the plasma membrane
• cells can be homogenized by being forced through a small hole
• cells can be put between a plunger in a glass vessel
• isolation allows scientists to separate cell components by sedimentation
• velocity centrifugation purifies cells by speed
• equilibrium centrifugation purifies cells based on density
• enzymes catalyze reactions
• structural proteins provide support to the cell
• transport proteins carry molecules and ions
• motor proteins generate cell movement
• storage proteins store amino acids and ions
• signal proteins carry signals from cell to cell
• receptor proteins detect and transmit signals for the cell
• gene regulatory proteins bind to DNA to toggle genes
• proteins can be depicted by

  1. primary structure
  2. wire structure
  3. space filling structure
  4. ribbon structure
• the protein shapes are:

  1. globular
  2. membrane
  3. fibrous
• globular proteins are soluble
• protein domains are portions of proteins that fold and fuction on their own
• most protein synthesis regulation happens during RNA synthesis initiation
• genes are regulated by transcription factor proteins