Menaquinones (MK) are hydrophobic molecules that consist of a naphthoquinone headgroup and a repeating isoprenyl side chain and are cofactors used in bacterial electron transport systems to generate cellular energy. We have previously demonstrated that the folded conformation of truncated MK homologues, MK-1 and MK-2, in both solution and reverse micelle microemulsions depended on environment. There is little information on how MKs associate with phospholipids in a model membrane system and how MKs affect phospholipid organization. In this manuscript, we used a combination of Langmuir monolayer studies and molecular dynamics (MD) simulations to probe these questions on truncated MK homologues, MK-1 through MK-4 within a model membrane. We observed that truncated MKs reside farther away from the interfacial water than ubiquinones are are located closer to the phospholipid tails. We also observed that phospholipid packing does not change at physiological pressure in the presence of truncated MKs, though a difference in phospholipid packing has been observed in the presence of ubiquinones. We found through MD simulations that for truncated MKs, the folded conformation varied, but MKs location and association with the bilayer remained unchanged at physiological conditions regardless of side chain length. Combined, this manuscript provides fundamental information, both experimental and computational, on the location, association, and conformation of truncated MK homologues in model membrane environments relevant to bacterial energy production.

The correct use of micropipettes has been investigated in an undergraduate, introductory lab experiment intended for chemistry and biology majors. This lab experiment involves the use of micropipettes for accurately mixing, transferring, and applying a specific amount of dye to a cotton bandana. The data resulting from this experiment is a color wheel that displays the amount of dye transferred based on the volume of the micropipette set by the student. Student learning outcomes for this experiment include the ability to choose the correct micropipette for the volume needed, set the correct volume on a micropipette, properly draw up solutions, and use proper dispensing technique. The development of experimental foresight and improvement in students' planning was an unintentional learning outcome. A prelab survey assessing students' confidence in accurately using micropipettes shows that a majority of first-year students had not used micropipettes in high school (85%) but did in their firstsemester science course (60%) before taking this course. The majority of those students have confidence in their ability to choose the correct micropipette, draw up the liquid, and dispense it properly. There was less confidence in setting the correct volume on the micropipette. The postlab results show that some students still had issues in setting volumes on micropipettes correctly and in dispensing the liquid. Additionally, the postsurvey suggests that setting the correct volume on the micropipette was the most learned skill from performing the lab. Overall, after performing the lab exercise, 92% of the students were confident in their ability to choose the correct micropipette and load and dispense liquid properly compared to 62% before performing the exercise.

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