BIOL 311

Milstein's group in 1972 used a cell free mRNA synthesis that showed when RER is added to the in vitro the protein is 20+ amino acids shorter than the mixture without RER. This was critical to the discovery of: hondrial targeting sequences b. signal peptidases/signal sequences c.SRP/SRP receptor d. Role of GTP/GDP in the RER protein synthesis e. Importance of trans-membrane potential across RER membrane and the role in protein synthesis - Answer Signal peptidases/ signal sequences ...

Microtubules - Answer Involved in mitosis and in non-dividing cell often radiate out from a MTOC (microtubule organizing center) How much of proteins do actin filaments make up - Answer 10% in muscle cells, 1-5% in normal cells, most abundant protein in muscle cells Molecular weight of actin filaments - Answer 42000 - G-actin (globular) How many actin genes are there - Answer 6 in humans that each encode an isoform Alpha actin - Answer Associated with contractile struc...

Lysosomes and proteasomes - Answer -Both degrade molecules, especially proteins Christian de Duve - Answer -Won Nobel Prize for discovering lysosomes -1955 -First to use a centrifuge to purify organelles -Created pellets (intact vs injured) -Intact showed respiratory activity due to mitochondria, injured showed hydrolytic activity due to lysosomes Lysosomes - Answer -Contain hydrolytic enzymes -Cleave to degrade most normal molecules/proteins -Enzymes not typical. Optimum p...

Dark Specimen, bright viewing field requires staining Pathologist, histologist, cytochemistry Iden - Answer 1. Bright field microscopy/compound light microscopy isolate the tissue or organ, choose a fixative that cross-links protein (formaldehyde), remove water and the fixative, replacing it with ethanol, replace ethanol with xylene, replace with molten paraffin and let solidify, cut 10–15-micron sections, remove the wax by doing the above steps in reverse, and stain with dye - Answer...