Crash Course: Biology

1. Carbon

Biology is the study of life—a four-letter word that connects you to 4 billio...

2. Water

Science offers a way of discovering and understanding the world around us, dr...

3. Biological Molecules

A biologist’s natural habitat is anywhere questions about life are being aske...

4. Animal Cells

Here on Earth, life is dizzyingly diverse—but it’s also surprisingly organize...

5. Membranes & Transport

Ecology is the study of the interactions of living things with each other and...

6. Plant Cells

Community ecology is the study of interactions between different species of l...

7. ATP & Respiration

When the Bald Eagle population started to decline in the mid-20th century, sc...

8. What Is Climate Change?

Life on Earth has weathered boiling-hot oceans and volcanic-ash-darkened skie...

9. The Effects of Climate Change

Climate change shakes up all of Earth’s systems, including the living ones. I...

10. DNA Structure & Replication

Some scientists believe we are in the middle of Earth’s sixth mass extinction...

11. What a weirdly long giraffe nerve can teach us about evolution

From a single-celled common ancestor, evolution has brought us all of Life’s ...

12. Microevolution: What's An Allele Got To Do With It?

Whether we’re talking about tigers, trees, or tarantulas, evolution happens a...

13. Natural Selection: Life's Way of Stayin' Alive

There are lots of ways that evolution happens, and natural selection is just ...

15. Where Do Species Come From? (Speciation)

How can you tell two species apart? It’s not always simple. In this episode o...

16. How did life begin? (Evolutionary History)

Humans may have been around for a long time, but life has existed for way lon...

17. How We're All Related (Phylogeny)

Crocodiles, and birds, and dinosaurs—oh my! While classifying organisms is no...

18. Humans Develop Butt First (and other insights from the Tree of Life)

Everywhere you look on Earth, you’ll find wonderful and diverse living things...

19. Humans Didn't Evolve From Chimps (Human Evolution)

What’s a human? And how did we become humans, anyway? In this episode of Cras...

20. What is Life Made of? (Carbon & Biological Molecules)

Despite the diverse appearance and characteristics of organisms on Earth, the...

21. A Love Letter to H2O: Water & pH

This is a love letter to water, life’s solvent, and one of the most wonderful...

22. How We See What We Can't See (Microscopes)

There’s an immense world of tiny stuff within us and around us—but how do we ...

23. A Tour of the Cell

The cell is the basic unit of life, and our understanding of it has advanced ...

24. How Does Stuff Get Into Your Cells? (Cell Membranes)

The cell membrane is a protein-studded phospholipid bilayer that not only pro...

25. How Do Cells Communicate? (Cell Communication)

Even though it might seem like our bodies are on autopilot, there is a whole ...

26. How Do We Get Energy? (Chemical Reactions)

27. How do cells get their energy? (Electron Transport Chain)

28. Photosynthesis: The Original Solar Power

29. Mitosis and the Cell Cycle

30. Why Are All Humans Unique? Meiosis

31. Why Your Cat Looks Like That: Genetics

32. Nature? Nurture? Not so simple: Genetic Traits

33. Our Instruction Manual for Existing: DNA Structure & Replication

34. How mRNA helped save lives: DNA Transcription

35. How RNA gets translated into protein power

36. How Genes Express Themselves

If nearly all your cells have the same DNA, why are muscle cells so different...

37. Is drinking milk a Superpower? Genetic Mutations

Science fiction is full of superpowered mutants, but in reality, mutations ar...

38. We’re full of bacteria!

Bacteria often get a bad rap, but they’re some of our best partners in scienc...

39. How Do Vaccines Work?: Viruses & Vaccines

From the flu to COVID-19, viruses are a major threat in our everyday lives. I...

40. Algorithms Aren’t Just for TikTok: Bioinformatics

On its own, a huge DNA sequence is a meaningless pile of data — so, how do bi...

41. Why We Aren’t Just One Big Cell: Multicellular Function

There are countless types of plants and animals on Earth, but how do they wor...

42. Plants Are Hardcore: Plant Anatomy & Physiology

Plants may not seem like they’re doing much, but if you look closer, you’ll f...