21. The concentration of methylene chloride ranged from 0 to 15 parts per billion. 22. The methylene group projects from the plane of the six coordinated carbon atoms. 23. Methylene -THF is then used by serine hydroxymethyltransferase to synthesize serine from glycine.24. Methylene blue can be used to stain plant cells25. Rarer modifications can occur at oxidized methionines and at some methylenes in side chains. 26. Thus, the two products are S-adenosylhomocysteine and phospholipid methylene fatty acid. 27. Eventually the methylene group is further reduced and released as a molecule of methane. 28. Methylene blue is reduced to colorless leucomethylene blue.29. Simple carbenes such as the methylene radical and dichlorocarbene are not regioselective towards insertion. 30. She noted that the methylene blue dye used in the experiment was not reduced.