Introduction to Microbiology - Online Tutor, Practice Problems & Exam Prep

Introduction to Microbiology Channel

Hi, everyone. Welcome to the microbiology channel in Pearson Plus. My name is Jason, and I'm an experienced biologist and science educator. My job is to help you learn and understand the content in this course to prepare you for your exams, while also having some fun along the way. I have a master's degree in applied molecular biology and diverse career experiences, including genetics research at Johns Hopkins University and many years of teaching as both a college professor and a professional tutor. In this microbiology video-based course, we'll explore some of the most commonly taught topics, including prokaryotic and eukaryotic cell structure and function, dynamics and control of microbial growth, microbial genetics and metabolism, viruses, the immune system, and much, much more. We've strategically developed this course with you in mind to maximize your learning. Our video content is highly engaging and can be adapted to your class textbook. We have dozens of effective memory tools and mnemonics to help you remember critical information for your test. Also, every video has a downloadable lesson worksheet for you to print off, allowing you to follow along as you watch. There's simply no better way for you to learn and prepare for your exams. If you have any questions along the way, post them in the comments section of any video, and our team will get right back to you. So again, welcome to the microbiology channel in Pearson Plus. We're super excited to have you here. So once you're all ready, let's get started.

Introduction to Microbiology

Hey there. Welcome to Clutch Prep Microbiology. My name is Jason, and I'll be your instructor throughout this course. If you have any questions about the content in our videos, feel free to post your questions in the comment section of the video, and one of our tutors will get back to you as soon as possible. Now that being said, let's go on and get started with our introduction to microbiology. Microbiology can be defined as the scientific study of microbes, which are organisms and infectious agents that are simply too small to be seen by the naked eye alone. In the field of microbiology, in order to study these really, really small microbes, we need to use microscopes to allow us to study them. Later in our course, we'll talk a lot more about microscopes, but for now, we're going to focus more on this term microbiology. The term microbiology can actually be defined simply by looking at its roots. Notice that the prefix micro, which is a prefix found in microbiology, means small, and so in the field of microbiology, the main focus is really really small organisms and infectious agents. The word biology means the scientific study of life. The main focus of microbiologists is to study living organisms that are simply really really small. It's also important to note that although microbiologists mainly focus on living organisms that are really really small, they sometimes also study nonliving infectious agents that are really really small. And that's because these nonliving infectious agents like viruses, for example, can infect and affect organisms that are really really small. We'll be able to talk more about this idea as we move forward in our course. It turns out that the smallest and the most basic or the most fundamental unit of life is actually the cell. Moving forward in our course, we're going to talk a lot about the structure of cells and the functions of cells, and we'll also talk about many different types of cells as well. The term organism is a really broad term because the term organism can refer to any individual form of life. The term organism could be referring to a unicellular organism or an organism made of only 1 single cell, or the term organism could be referring to a multicellular organism that is made up of multiple cells. The term microorganism again has that root or that prefix micro, which we already said is a prefix that means small. Microorganism is simply an organism, a living organism, that is simply too small to be seen with the naked eye alone. Once again, we need the aid of microscopes in order to visualize and study these microorganisms, these organisms that are really really small. Notice that down below we're also defining microbes again for a second time, even though we technically already defined it up above. The reason for that is because sometimes the term microorganism is used in a synonymous way to the word microbes. However, technically, these are not synonyms. Microorganism and microbes have subtle differences in their definitions. Here we put these two definitions side by side to help you better understand how these two terms are similar, but also how they are different. Once again, microorganisms is referring to living organisms that are really, really small. The term microbes includes microorganisms. So it also refers to living organisms that are really really small. However, the term microbes also is referring to nonliving infectious agents such as viruses for example that are also too small to be seen by the naked eye. And so, microbes, includes microorganisms, but it also includes nonliving infectious agents. Whereas the term microorganisms only is referring to living organisms, but does not refer to nonliving infectious agents. Hopefully that can help you better understand the differences between those two key terms. If we take a look at our image down below, notice on the left hand side, we're showing you a human being, a microbiologist if you will, which is a living organism of course. More specifically, this human is going to be a multicellular organism because humans are made up of many cells, 1,000,000,000,000 and 1,000,000,000,000 of cells. Notice that this microbiologist, in order to study microbes which are really really small, needs to use a microscope. Again, we'll talk a lot more about microscopes later in our course. But the microscopes allow the scientists to visualize the microbes, which are really really small. Once again, the term microbes is going to include really really small microorganisms, living microorganisms, such as bacterium that you can see right here. This is one single celled bacteria. And, microbes also include some nonliving infectious agents, such as viruses, for example, which are lacking many of the characteristics of life and so are generally not considered alive. But they are nonliving infectious agents, and sometimes they are still studied by microbiologists because these nonliving infectious agents can sometimes affect cells, living microorganisms. And so over here on the right hand side, we're showing you a collage here of many different images of the microbial world, all of the microbes that exist such as viruses and, specific type of archaea and, virus, other viruses and bacteria, and single-celled organisms, and these are called bacteriophages. And so we'll talk a lot about the microbial world, basically the different types of microbes, microorganisms, and nonliving infectious agents as we move forward in our course. But for now, this here concludes our introduction to microbiology. And again, we'll be able to learn a lot more as we move forward. So I'll see you all in our next video.

Which of these is considered a microbe but NOT a microorganism?

• A. SARS-CoV-2 (Covid-19 virus).
• B. Escherichia coli bacterium
• C. Necator americanus (a hookworm).
• D. Dinobryon divergens (Golden Algae).
• E. None of the above, all are microorganisms.

Which of these are characteristics of microorganisms?

• A. Microorganisms are so small they cannot be seen with the naked eye.
• B. Microorganisms can be multicellular or unicellular.
• C. Microorganisms include the smallest units of life and non-living infectious agents.
• D. Microorganisms can have DNA or RNA as their genetic material.
• E. A and B are correct.
• F. C and D are correct.
• G. All of the above are characteristics of microorganisms.

Discovering Microorganisms

In this video, we're going to focus on the discovery of microorganisms. It turns out that humans were not always aware that microorganisms even existed, let alone that they exist in pretty much every conceivable environment around us. The existence of microorganisms was actually discovered just a couple of hundred years ago during the time period between 1665 and 1674.

In 1665, an English microscopist named Robert Hooke was actually the very first person to visualize and depict or create a drawing of a microorganism. More specifically, Robert Hooke described a common bread mold known as mucore as a microscopical mushroom. If you take a look at the image down below over here on the left-hand side, there's a little portrait of Robert Hooke, who lived from 1635 to 1703. Here is an image of Hooke's microscope that he used to visualize the very first microorganism and depict the very first microorganism. Over here on the right is Robert Hooke's drawing of the bread mold, his depiction of the bread mold.

Now in 1674, just a few years later, a Dutch merchant named Antony van Leeuwenhoek analyzed a drop of lake water with a microscope and he saw microbes, many different types of microbes other than just these microscopical mushrooms. Antony van Leeuwenhoek described and depicted protozoa, which are very small eukaryotic organisms. We'll talk about them more later in our course. He also depicted bacteria, which are very small prokaryotic organisms. Again, we'll talk more about those later in our course. Antony van Leeuwenhoek depicted a whole different set of microorganisms and called these microorganisms animalcules, which really just means little animals.

If you take a look at the image down below, you can see a portrait of Antony van Leeuwenhoek, who lived from 1632 to 1723. Here is an image of Antony van Leeuwenhoek’s microscope that he used to visualize the protozoa and bacteria. Here is an image of the depictions that Antony van Leeuwenhoek created when he observed that lake water. Again, he called them animalcules or little animals, and you can see that there are many different types of protozoa and bacteria that he had drawn in his images.

While Robert Hooke observed a microscopical mushroom, a common bread mold, which is a little bit larger than these other protozoa and bacteria were, they are still at the microscopic scale. Both deserve equal credit for revealing the microbial world. Due to Robert Hooke and Antony van Leeuwenhoek's discoveries, they revealed that there was a microbial world of really small organisms and infectious agents that were all around us.

This concludes our lesson on discovering microorganisms, and we'll be able to get some practice applying these concepts as we move forward in our course. So, I'll see you all in our next video.

Antonie van Leeuwenhoek observed microorganisms under his microscope and called them 'animalicules' (little animals). Which microorganisms did he observe?

• A. Algae and bacteria.
• B. Bacteria and protozoa.
• C. Bacteria and viruses.
• D. Protozoa and viruses.
• E. He observed all of the above.

Robert Hook's and Antonie van Leeuwenhoek's microscopes were not powerful enough to observe:

• A. Roundworms.
• B. Escherichia coli bacteria.
• C. Yeast cells.
• D. Viruses.