Hey, it's Sanjeev Pandey, 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 am saying, you're probably a human being, butwhatever you are, you are definitely a living organism, as you fulfill all the criteriawe have to define what life is and does. 

You move around, you use energy, you respond to stimuli, and you reproduce, or you willone 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 on 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 somephysics.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 uplife, 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 arefor you as well, but it may be best to first go back to some of my other tutorials in orderto learn about the things that make up cells, especially atoms and molecules, which we coverin general chemistry and organic chemistry, as well as the larger biomolecules that wetalk about in biochemistry, because without an understanding of these subjects, biologicalprinciples have to be taken more or less on faith.We hear that DNA is the genetic code, but how? But if you really understand chemistry and biochemistry, biology starts to make a lot of sense, so many students will return to biology later in life after studying the other sciences. 

Whatever your level of knowledge or your intention with these tutorials, feel free to click onthe cards in the corner of the screen when you see them, to be taken to a different tutorialin 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 toexplore 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 impossibleto predict just from learning about small molecules, and the way that human behavioris 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.