What Makes Something "Alive"?
The meat of our second episode begins with John, James, Kat, and special guest Robbie exploring the essence of life. They all struggle in determining the explicit qualities that makes something living and applying these qualities to examples such as trees and fire to determine if they fit the criteria for life. The traits listed are as follows:
Organization - Living things are organized. All living things are made of tiny structures known as cells. In multi-cellular organisms, cells organize into tissues, tissues organize into organs and so on.
Reproduction - Living things make other living things (of the same species).
Growth - Living things grow.
Response to Stimuli - Living things will adjust to a change in their environment.
Metabolism - Living things carry out chemical processes to maintain a state of living.
Evolution - Living things evolve (explained later in the episode).
Homeostasis - Living things maintain equilibrium regarding properties such as temperature, acidity, etc.
The Feynman Technique for Learning is discussed which states that there's a difference in knowing the name of a concept and really knowing that concept. If we can't explain life to a five year old, do we truly understand it?
Scientists Mentioned: Richard Feynman
Resources:
What is Life? Is Death Real? - Kurzgesagt
What is Life? - Khan Academy
Cells: The Smallest Unit of Life
Robert Hooke did not invent the microscope (oops) but he did coin the term "cell" to describe the room-like structures he saw in cork under the microscope. Many other scientists noticed these room-like structures present in all living things and thus cellular biology was born. The cell is considered the smallest unit of life as it hits all seven of the criteria listed above. Cells can be seen as "protein factories" making things like hair and enzymes. Nothing that the cell is made of is considered living. Organic (carbon-based) molecules are the building blocks of cells but the cell is foundation of life and the smallest thing considered alive. At the atomic level, life is meaningless. Everything is made up protons, neutrons, and electrons arranged in different ways. If everything is made of the same stuff, what makes life so special?
Scientists Mentioned: Robert Hooke
Resources:
What is a Cell? - National Library of Medicine
How Cells Work - How Stuff Works
The Origin of Life
We see life happening all around us. But where did it come from? How did life begin here on Earth? What made molecules work in just the right way to make cells? Two ideas are discussed and explored:
Panspermia - Jizz covered alien rocks. This idea states that life came to Earth from space! Ancient microbial life might have survived on meteorites that crashed into Earths surface. We might all be aliens!
Abiogenesis - The more accepted theory of the two. This idea states that life spontaneously came into existence on ancient Earth. The famous experiment that supports this theory is the Miller-Urey Experiment. This experiment gives us evidence that organic molecules (the building blocks of life) CAN be created in early Earth's atmosphere. From here, it is thought that these organic molecules began interacting enough to eventually create the very first cell.
Scientists Mentioned: Stanley Miller, Harold Urey
Resources:
Origin of Life: How Life Started on Earth - Nova
Abiogenesis - Wikipedia
Panspermia - Wikipedia
Evolution
First the difference between a scientific theory and a scientific law is discussed. This is because evolution is both a law and a theory. The debunked theory of lamarckian evolution is presented which state...