How the MCAT Tests - Lab Techniques 1

In this introductory paragraph, Maggie, a former professional MCAT tutor and current medical school student, along with her brother John, welcome viewers to their educational channel. They aim to teach MCAT sciences for free. Today's focus is on high-yield separation and lab techniques for the MCAT, which are essential for scoring well. The video complements their high-yield ebook available for purchase on their website. Maggie mentions that she has previously covered research methods, and viewers can expect a similar approach for separation techniques and lab methods, with an emphasis on high-yield topics such as IR spectroscopy, gel electrophoresis, and column chromatography. She also briefly touches on lower-yield topics like mass spectrometry, blotting, and UV spectroscopy, noting their relevance and frequency of appearance on the MCAT.

This paragraph delves into the specifics of various lab and separation techniques, starting with mass spectrometry, which separates molecules based on their mass-to-charge ratio. It then moves on to nuclear magnetic resonance (NMR) spectroscopy, highlighting its relevance to medical imaging through MRI machines. The paragraph continues with a discussion on blotting techniques—Southern, Northern, and Western blotting—which are used post-gel electrophoresis to determine the quantity of DNA, RNA, or proteins in a sample. Eastern blotting is also mentioned but noted as not commonly tested on the MCAT. UV spectroscopy is covered next, focusing on the absorption of UV light by conjugated molecules. The paragraph transitions into a detailed explanation of infrared (IR) spectroscopy, which identifies functional groups in molecules through their vibrational frequencies. A table from their high-yield book lists common functional groups and their specific IR resonance frequencies, emphasizing the importance of recognizing these for the MCAT.

The final paragraph explains gel electrophoresis, a lab technique used to separate molecules based on size and, sometimes, charge. It distinguishes between native gel electrophoresis, which considers both size and charge, and SDS-PAGE, which coats molecules in a negative charge to eliminate charge differences, focusing solely on size for separation. The process of gel electrophoresis is described, from loading molecules into wells to applying a current that moves the molecules through the gel based on their size. The paragraph clarifies misconceptions about the polarity of the cathode and anode in gel electrophoresis and explains how the movement of molecules is influenced by their charge and size. It also touches on isoelectric points and how they can be used to separate proteins in an electrophoresis gradient. The video concludes with a mention of future content on chromatography techniques and a call to action for viewers to engage with the channel's community and resources.