GPCR Signaling on the MCAT: Gs/Gi, Gq, and Signal Amplification

In this Jack Westin MCAT Podcast episode, Mike and Molly break down MCAT signaling cascades with a clear, test-focused walkthrough of G protein–coupled receptors (GPCRs). You’ll learn the core GPCR structure, how GDP → GTP activation works , why signaling pathways create amplification, and how cells shut signals off with built-in termination steps.We cover the high-yield cAMP pathway in detail, including Gs vs Gi, adenylyl cyclase → cAMP → protein kinase A (PKA), plus the key ideas behind the Gq pathway (PLC and calcium signaling). We also connect GPCR signaling to common MCAT contexts like hormones, fast cellular responses, and a classic passage-style example (cholera toxin) to show how the AAMC tests cause-and-effect in pathways.In this episode, you’ll learn: 🌊 What a signaling cascade is: signal → receptor → transduction → amplification → response → termination🧬 GPCR basics (membrane receptor + G protein alpha/beta/gamma)🔄 How GPCRs activate G proteins (GDP swapped for GTP, then subunits dissociate)🚀 The Gs pathway: adenylyl cyclase → cAMP → PKA → phosphorylation🛑 The Gi pathway: inhibiting adenylyl cyclase and lowering cAMP🧩 The Gq pathway: PLC, second messengers, and calcium📈 Why amplification matters (small signal, big cellular response)⏱️ How signaling is shut off (GTP hydrolysis + cleanup of second messengers)👁️ Vision callback: how GPCR-style signaling shows up in phototransductionNext up: Smell & taste and how these senses rely heavily on GPCR signalingWant to learn more? Shoot us a text at 415-855-4435 or email us at [email protected]! 📱📌 Success Advising: https://calendly.com/academic-advising-4/jack-westin-academic-advising?utm_source=spotify&utm_medium=podcast💻 Try our Chrome Extension (video solutions to every AAMC passage) https://tinyurl.com/4jw5pad8📚 Free Resources: https://jackwestin.com?utm_source=spotify&utm_medium=podcast🎓 Live Education Sessions: https://jackwestin.com/sessions?utm_source=spotify&utm_medium=podcast👨🏻‍🏫 Courses: https://jackwestin.com/courses?utm_source=spotify&utm_medium=podcast🙋 Tutoring: https://jackwestin.com/services/live-online-mcat-tutoring?utm_source=spotify&utm_medium=podcast📸 Follow Us On Instagram: https://www.instagram.com/jackwestinmcat?utm_source=spotify&utm_medium=podcast👥 Join our Facebook Study Group: https://www.facebook.com/groups/freemcatprep?utm_source=spotify&utm_medium=podcast