In the 1950s, christian anfinsen demonstrated the renaturation of the protein ribonuclease (rnase) in vitro. after reduction (to reduce the disulfide links) and the addition of urea (to denature the protein), the protein was in an unfolded state. after removing the urea and the reducing agent, the protein refolded, with greater than 90% activity. if the urea were removed after oxidation occurred, the protein had less than 5% activity. why would the protein not refold correctly if the urea were removed after the reducing agent was removed? (in other words, what would happen if the urea were removed after oxidation? ) choose the best answer.

(a) urea would participate in weak bonding interactions with rnase, preventing oxidation of cys.
(b) the protein would not fully unfold (denature).
(c) disulfide bonds are not positioned correctly unless weak bonding interactions are present.
(d) contaminants in the rnase preparation would form covalent bonds with the protein, preventing reactivation.

The tasmanian devil, a marsupial carnivore, is facing extinction due to devil facial tumor disease (dftd) which causes bulging cancerous lumps and lesions to erupt around the face and neck — often causing enough deformation to make seeing or eating difficult. dftd has evolved into a contagious cancer, a trait that is unique among cancers. devil mating behavior involves biting around the head and neck, allowing cells from one individual — especially cells from the crumbly dftd tumors — to be transferred to the wounds or face of a new individual. this marsupial was once found across australia, but sea levels rose, isolating the tasmanian population, while the australian population went extinct. what would be an outcome of genetic isolation that is likely to have impacted the spread of dftd? a) reduced territory puts diseased individuals in greater contact with non-diseased ones. b) inbreeding results in less variation in facial features so the cancer is generally fatal. c) genetic isolation has made it difficult for scientists to develop a vaccine against dftd. d) the lack of genetic variation in the immune system of tasmanian devils minimizes resistance to the disease.

During endocytosis, cells expel what they don't need take in what they need shrink due to loss of water

Where substance is produced during cellular respiration