Introduction to Biology: What is Life?

Hey it’s Professor Dave, I wanna tell you
about biology. Have you ever looked in the mirror and wondered
exactly what it is that’s looking back at you? Of course it’s you, but what are you? If you’re able to understand the words I’m
saying, you’re probably a human being, but whatever you are, you are definitely a living
organism, as you fulfill all the criteria we have to define what life is and does. You move around, you use energy, you respond
to stimuli, and you reproduce, or you will one day, so you don’t disappoint your parents. So what are living organisms made of exactly? There are many ways to answer that question,
it just depends how deep you want to go. The smallest things inside of you are tiny
particles called quarks and electrons. These come together to make atoms, which make
up molecules, which make bigger molecules, until we eventually get to a cell. A single cell is the smallest thing that can
be considered alive, and everything that’s alive, on earth anyway, is made of cells,
whether just one cell, or many trillions of cells. From bacteria to human beings, we are all
made of cells. If you want to know more about quarks and
other particles, you’ll want to study some physics. For atoms and molecules, you’ll need chemistry,
and once those molecules get very big, you’ll need biochemistry. But once we get to an entire cell, we must
be studying biology, because cells make up life, and biology is the study of life. Biology can be tricky to teach, because it’s
often the first science we learn in high school, which means we sometimes have to learn things
that will be difficult to understand because we haven’t yet learned about the subjects
that biology breaks down to. Nevertheless, if you’re a young high school
person learning biology for the first time, you’ve come to the right place, and you
can feel free to start your scientific journey right here. If you’re a bit older and looking for more
comprehensive knowledge, these tutorials are for you as well, but it may be best to first
go back to some of my other tutorials in order to learn about the things that make up cells,
especially atoms and molecules, which we cover in general chemistry and organic chemistry,
as well as the larger biomolecules that we talk about in biochemistry, because without
an understanding of these subjects, biological principles have to be taken more or less on
faith. We hear that DNA is the genetic code, but
how? To many, it seems like magic. But if you truly understand chemistry and
biochemistry, biology begins to make a lot of sense, which is why many students will
come back to biology later in life, after having learned the other sciences. Whatever your level of knowledge or your intention
with these tutorials, feel free to click on the cards in the corner of the screen when
you see them, to be taken to a different tutorial in another one of my series that will explain
what you are looking at in more detail. Remember, the more we know about nature, the
less and less it seems like magic. What’s amazing about nature is how tiered
it is, with so many different realities to explore at various levels of size. Every time we zoom out a couple orders of
magnitude, a new and more complex reality emerges from the prior, like the way the complexities
of a cell and its functions would be impossible to predict just from learning about small
molecules, and the way that human behavior is so much more complicated than mere cellular
processes can immediately account for. But if we want to learn science, we have to
choose a place to start, and if for you that place is biology, then let’s begin. In this course we will learn about the parts
of the cell, a variety of single-celled organisms, and the way that these evolved over a few
billion years to become all the living things on earth today. But how exactly did life first come about
on the earth? Is this something that anyone could ever truly
know? Let’s talk about this in the next clip.