overview of biology. Biology as most of you know is the study of life. But former students

that I have don't usually go on to major in biology. They go into major in biochemistry

or molecular biology or wildlife ecology or evolutionary biology. Or they become a biophysicist.

And so there are lots of different disciplines that use the concepts that that you're going

to learn in biology. And even myself, I worked in a biofilm lab for a couple of summers.

And just having a basic understanding of biology, I was able to follow most of the conversations

that the professors were having. Just understanding some of these four concepts. And so basically

those four big ideas were developed by the college board as they developed the new AP

biology framework. But they're pretty good standards. And so those are evolution, free

energy, information and systems. In other words these are four big ideas that are going

to cover all of biology. And so as you watch the other podcast you should always be looking

back to these concepts and figuring out which ones, if many, it might fit into. And so the

first one we'll start with is evolution. This is always where I like to start the year.

And this right here is a picture of Charles Darwin, early in life when we was starting

to formulate his ideas on natural selection. And if you ask people, what did Charles Darwin

do? Lots of times they will just say, oh he invented biology, or he invented evolution.

And that's really not super accurate. He did, was a proponent of evolution. And I love this

right here. It's taken right out of his notebook. And basically he's, this is a private notebook,

and what he's saying is I think that all life shares common ancestry. There was one life

form on the planet and that split into two and many after that. And if we look at, this

is the phylogenetic tree of life that we have today, it looks a whole heck of a lot like

that early drawing of Darwin, with bacteria, archaea, bacteria and eukarya on the side.

And if we find us, we're way up here on the animals. And so he was a proponent of what

we call macroevolution. In other words, species forming new species. But what's really makes

him special is that he was the first one to come up with a mechanism to explain how adaptation

and evolution actually works. And that's called natural selection. The quintessential example's

with the peppered moths. And so peppered moths in Europe have two different phenotypes or

physical appearances, dark and light. The trees were light, relatively, but during the

industrial revolution so much soot coming from the coal was making the trees turn black.

And so if you were a bird, back in the day, you would pick on the white moths. But as

the trees got darker and darker and darker then they started to blend in and the birds

were starting to isolate on these white moths. And so we saw a change in the number of each

of those. And so basically the moths aren't changing their appearance, it's just selection

in nature that's determining that. And so basically it's the idea of natural selection.

Now the one thing that you should remember is that there are actually five things that

can cause evolution. And natural selection is simply one of those five. The other four

are small sample size, non random mating, mutations and then immigration or emigration,

movement into or out of a population. But if we ever get change in the frequency of

a gene pool, evolution has occurred. Natural selection is that fifth one and the nice thing

about natural selection is that it allows organisms to become better adapted to their

local environment. And that's all evolution really is. Next one is the idea of free energy.

And what this means is that energy is going to flow from the sun to the earth. On the

earth plants or producers are going to use the process of photosynthesis to convert the

energy into that, into sugar. So converting it into sugar so they can build plants out

of and they can use for energy. Because plants also do another process called respiration.

Respiration is a way to release the energy found in sugars. Generally in the form of

ATP. And so energy is going to flow in this direction to the earth, through photosynthesis,

to sugars, to respiration, to ATP. And then it eventually all leaves as something called

heat. And so free energy is a big concept. Basically what it means is it's energy that's

available to do work. Or energy that's available to do something. Now another thing that's

important though within this idea of free energy is just maintaining a stable internal

environment. In other words, in this cruel universe, where energy is flowing, it's important

that you maintain what's called homeostasis. And so also within this big theme of free

energy is the idea of homeostasis. Maintaining a stable environment. And that's what a plant

does. If you can't maintain homeostasis, then you're dead. And so the way we do that is

using a feedback mechanism. And so the best example I can come up with for feedback mechanisms

are these speed signs like this. So you drive by. Your speed is 30 miles an hour. It's supposed

to be 30 miles an hour and so you notice that your speed is a little fast and so you slow

down. And now all of a sudden let's say it's 26. Then you speed up. And our body is doing

the same thing. Like for example, inside our body it's 98.6 degrees Fahrenheit. And how

do we maintain that? We maintain that through homeostasis. But there's so many other things

that we maintain inside our body like blood glucose level, blood calcium level. All of

these things have to be maintained. Osmolarity. In order to keep ourselves alive. And we're

utilizing free energy to do that. Next thing would be the idea of information. That's information

flow from organism to organism. Generation to generation. And remember the one thing

that we use to do that is DNA. And so DNA has really taken over biology. When I learned

biology it wasn't as big role as it is today. And when your grandparents studied biology,

really they didn't know much about DNA at all. In fact in the 50s is when they finally

unlocked the shape of it. But this is what we would call the central dogma of life. And

what that means is that basically the DNA sits in the nucleus of your cell. It makes

RNA. And that RNA makes proteins. And then those proteins make you. And so you are basically

the result of proteins and protein action. But it's the blueprint or the DNA inside you

that says this is the proteins that you need to make and when you need to do them. And

so that information flow is super important. And if we were to go back to that first organism,

what did it have? Well it had DNA. And that DNA has been copied and mutated and changed

and selected through time to create all the organisms that we have on our planet. So information

is super important. Within this would be the idea of genetics and genes. This over here

is Gregor Mendel, and really unlocked that idea, you probably learned how to do punnett

squares, but what a gene is, what an allele is, is important. And then one thing we're

starting to really figure out is that you're not static. In other words you're able to

respond to your environment. And so a big thing that's becoming more and more important

is cell communication. In other words cells are communicating, communication, I hope I

spelled that right. Cells are communicating with one another. So this right here would

be a signal transduction pathway where a ligand hits on a protein and you have a series of

chemical reactions. And so we can actually express a gene and we can make a protein to

do something. But nerves, hormones, pheromones, all these things are examples of cell communication.

So it's the transfer of information. Even a wolf howling at night is an example of information

transfer. So that's another major theme. And then the final one is the idea of systems.

In other words in biology we're built on this hierarchy of life, it's sometimes referred

to as. And what that means is that basically living things are made up of carbon compounds.

Those are organized into macromolecules which make organelles, which make cells, which make

tissues, which make organs, which make organ systems, which make organisms, which make

populations, which make communities and ecosystems and biomes and biospheres. So there's this

hierarchy of life. And so we have all these different systems. And at each of these different

levels what we start to get are emergent properties. Or properties that weren't there the level

before. And so systems and the way systems are organized is important. But just as important

as that are interactions. And so this right here is E.O. Wilson. He's probably the most

famous biologist alive today. But basically you would refer to him as the father of biodiversity.

And what he has become famous for showing is that in these major ecosystems, we have

interactions between different populations, symbiosis and so all of these systems are

interacting together. And so all of the organs in an organ system like the circulatory system

are working together. But so are all the populations in a community. And so systems and interactions

are also another major theme in biology. And so that's kind of the four major themes in

biology. It's again something that you always want to look back to when you're studying

new material. And I hope that's helpful.