How Do Molecules Cross the Cell Membrane? Channels, Carriers & Active Transport Explained

MCAT registration opens this week, and for 2027 there’s a big change: every test date opens at once. Here’s how to get the date you want, and what to do if you don’t. In this episode of the Jack Westin MCAT Podcast, Mike and Molly start a new chapter on strategy with a full walkthrough of MCAT registration. Both hosts have been through the process themselves, including a booking site crash, a scramble for a test center, and a long drive. They cover what to prepare beforehand, how the waiting room works, how to choose a test date, and what to do if your first choice is gone.

A congressman covers his microphone and whispers, “Say yes.” What does that moment have to do with the main idea of an MCAT CARS passage?

The AAMC released 166 new CARS questions across 27 passages. The whole team did the material over a weekend, ran the numbers, and compared notes. Here’s what changed, what didn’t, and how to adjust your strategy.

You’re basically a tube. Everything inside your digestive tract is technically still outside your body, and your cells only get what makes it across the lining.

Your innate immune system handles 99% of threats without you noticing. But when it's not enough, your body builds a custom-made response, one specific enough to remember an exact enemy for years. In this episode of the Jack Westin MCAT Podcast, Mike and Molly continue their immunology series with the adaptive immune system: the slower, highly specific branch of immunity that brings memory, precision, and long-term protection. Building on the last episode's innate immunity foundation, this episode walks through exactly how B cells and T cells get activated, how the body finds the right defense out of millions of possibilities, and why HIV is so devastating to this entire system.