Hey everyone, welcome to Professor Long's lectures in microbiology. These videos are intended for use by students who are enrolled in MyBiology2420 or Microbiology for the Health Science courses at Del Mar College. If anyone else out there in YouTube land finds them helpful, by all means, please hit like, hit subscribe, or provide me some feedback so that I learn how helpful they are for you, and I can continue to do these videos if I'm encouraged to do so.
Now, when you take microbiology... We're going to get into chapter one, the introduction of microbiology. We're going to go a little bit over the history of microbiology and some terminology to set some of the basic foundation of this course.
Now typically if you take microbiology, the course number throughout at least the state of Texas and most universities throughout the nation is 2420. Okay, this number tells you it's a sophomore level course. So you have freshmen, sophomore, junior, senior. This number tells you... tells you the number of hours, we combine the lecture and the lab, and there is a lab component for this course. So this is a sophomore level biology course.
Typically, in order to take sophomore level courses, you have to pass a certain number of freshman level courses, like freshman biology one and two, and some freshman chemistry. Now in their grand wisdom, the politicians that run things have decided that colleges are getting rich by making you take extra classes. They want you to hurry up up and get out and start paying taxes, at least in my opinion.
And so they have mandated that all associate's degrees be cut to 60 hours and all bachelor's degrees be cut to 120 hours. Well, the problem is some degrees require a few extra courses. My biology degree at one point required 128 hours and I graduated with even more than that. And some associate's degrees used to require 72 or 74 or 76 hours because Because in order for you to be credentialed as an institution to get a degree in nursing, your nursing students have to have a certain number of didactic or classroom learning and a certain number of hours in clinical.
And when you add all that up, plus the prerequisites, it would require about 72 hours or more. And those prerequisites very often are necessary to help you understand the information that they're going to be going over in the program. Well, politicians decide... well you guys are getting rich making them take extra hours, cut it to 60. But technically and legally they can't cut the hours of the program so they started cutting prerequisites and so now it's not even required that you have some freshman biology one and two and they're trying to even strip freshman chemistry as a prerequisite which hurts the learning in microbiology.
Now many of you may have had some biology before or some in high school but a lot of our students especially at the community college level are coming in sometimes 5, 10, 15, 20 years after high school, and now they're not required to have these other biology courses. And so I have to step back a little bit, and I want to refresh some of the concepts that you should understand or know in order to understand microbiology. So we're going to take a step back into some freshman biology when we do a lot of terminology as we go through this first lecture, okay?
So microbiology is a subtopic under the supertopic. or the subject of biology. So if I look at the term biology, and I'm a big word nerd, I like to break down words, and knowing roots and suffixes and prefixes helps you sometimes answer questions and understand material. It's really a lot of language.
It's a lot of vocabulary. Bio literally comes from the word bios, which means life, and logos or ology means the study of or the logic of. So biology...
is the study of life, the study of life processes, and everything associated with life. It's the study of life and the processes associated with living things. Okay? That's kind of a broad general definition, but it is a good one.
Okay? So that's what biology is. Microbiology is a subtopic under biology which has a whole myriad of topics that we could study. Ichthyology, anatomy, physiology, genetics, biochemistry, microbiology, ichthyology, ornithology, you know, all these ologies that we could study.
Now, in order to understand all of this, we have to understand what is the definition of life. Okay? Scientists have a very hard time defining life.
I'm going to read you a definition from a textbook of life. A living thing is a physical entity that exhibits characteristics that distinguish it from non-living or dead things. Life is a physical or living things are a physical entity that are comprised of characteristics that distinguish them from non-living things. What in the world does that mean?
So one of the ways that I like to think of defining life is life is a collection of these characteristics or traits that allow... us to determine whether something exhibits these characteristics and traits must be alive and something that is lacking one or more of these characteristics or traits cannot be defined as a living thing or as life. So I'm going to list those characteristics that you should understand.
Now different books have a different set and different number, but they all mostly cover the same ones. So if we're going to decide that something is alive or a living thing, it must be alive. must exhibit these characteristics, okay?
So I'm going to just write this out as the characteristics of living things or of life. One of them is organization. It's not just random chaos like some parts of the universe like if you looked inside the Sun all the random chemical reactions and nuclear reactions going on it's not that it's a very organized situation so living things are comprised of cells.
And we know that all living things are comprised of cells. And cells are the smallest living subunits of an organism. And some organisms are so simple that they're a single cell.
Now, When we look at cells, cells are made up of smaller units, and some of those units are called atoms. And you study a lot of atoms in chemistry, and we're going to do a lot of chemistry in this class. And atoms are all behaving independently, but sometimes when a couple of atoms come together and interact, they form a molecule. So a molecule is just a collection of atoms that are exhibiting a unique and identifiable behavior, or performing, the way I define it is they're performing a specific function.
A bunch of different molecules behave differently, like water and methane gas and amino acid and lipid. But when we combine molecules together sometimes, they start working together to exhibit a definable or a defined behavior. And we call those things organelles.
And then organelles, each with their own behavior, can work together to form cells. Now, not all cells are made up of a lot of organelles. that especially in microbiology and we're going to go over cell structure at some point but then cells can come together to form tissues and then organs and organ systems and organisms and we go through all of that in anatomy and physiology and a lot of biology but when it comes to microbiology sometimes with the organisms we're looking at are a single tiny cell which of us helps us define what microbiology is which we will do in just a moment another characteristic of life is that living things will exhibit what we call home homeostasis and if we look at homeostasis it means to stay the same stasis means static or to stay and homeo means same I did that backwards but this is same and this is to stay okay so the old idea is if it ain't broke don't fix it if your body is humming along functioning perfectly why would you alter what's working so the technical definition of homeostasis is the maintenance The maintenance of a constant and optimal internal environment, okay? That's homeostasis.
That's a definition that you should know because it is the central foundation of all of healthcare. If our bodies are functioning perfectly, we need... intervention.
If we're not in homeostasis, we're in what is called pathology. And in pathology, that is the study of disease or death and the processes that lead to that. As a matter of fact, we can, we'll define pathology later on.
But if your body is in homeostasis, you're not in pathology and vice versa. If you're in pathology, you're not maintaining that constant environment. Our body has feedback mechanisms to control that as do ...many of these microbiological organisms, but when that fails, sometimes we need to intervene with medicine, okay?
And a lot of the microbes we're going to be talking about result in pathology. And we'll see why and how in a time. appropriate. Now another characteristic that all living things exhibit is what we call metabolism. Now technically the definition of metabolism is the sum total of all biochemical reactions.
in the human body, okay? But in a general sense, metabolism is the ability to break down large molecules into smaller ones or assemble small molecules into larger ones and convert some of those compounds into energy. So metabolism is sort of all the chemical processes that are occurring in our body. If you eat a protein, your protein breaks down as broken up. Your body breaks that protein down into individual...
amino acids. So that would be catabolizing or breaking down a large molecule and then we take those amino acids we send them to our cells and we reassemble them into human protein. So we would be taking small molecules and building them into larger molecules assembling them together.
We call those anabolic reactions. Now in the world of chemistry we also refer to what we call degradation or synthesis reactions and we'll get into all that chemistry eventually. But metabolism, the ability to break things down and reassemble them and produce energy is a really important part of, or one of the important characteristics of all living organisms, okay? Now, another characteristic that is exhibited by living organisms is growth.
Growth as an individual to become bigger in size, or sometimes as an organism to increase the number of cells. And so we're going to look at microbial growth, we're going to look at how cells and some of these microbes will grow, how they... can increase in size through their metabolism and how they can also grow in number of cells. And that's another one of the characteristics of a living organism.
is reproduction, the ability to reproduce or make more of yourself. So metabolism we'll define as the sum total of all biochemical reactions in the body or of an organism, and that would be what we call catabolic. plus anabolic reactions. We're going to define those one day. Growth is to increase in size and or number.
And reproduction is to make more of yourself. Now these are Mr. Long general definitions, but they work. And so we're going to look at how organisms can sometimes reproduce and grow and metabolize and maintain their homeostasis.
A couple more of these characteristics. I'm running out of room at the bottom of the board, so I'm just going to go back up to the top, erase some of these, and add the last two that I want you to know. Now, some books have a few more than this. Break some of these out. into other categories or combine some of these into a category but nonetheless respond and really we should say respond to the environment okay living things can sense what's going on in the surrounding environment and then respond to those changes in the environment that allow them to continue to survive and so that is one of the characteristics of all living things and similar to respond to the the environment is to adapt.
Now to adapt means to change sort of in a long-term way over time to survive changes in your environment. So when we talk about respond to the environment and respond to changes in the environment, what we're talking about is sort of short-term things. When I talk about adapt, we're talking about long-term changes.
In an organism, to survive, changes in the environment. So, for example, if there's a particular organism... It has the ability for what we call motility or to move and it bumps into some predator, something that can kill it.
It can respond by swimming away or moving away from that organism. That's not adaptation, that's response. to a change or if there's a different if there's a chemical change in the environment then maybe the organism will change its metabolism so that it can grow and develop that's an immediate response to adapt means to alter the organism's functions over the long term to bigger changes in the environment. For example, if I were to take some bacterium that lacks a particular temperature and grows at a certain rate at a specific temperature, and over time the temperatures in that region start changing, maybe some of those bacteria will develop a new metabolic pathway to deal with the changes, the slowing of metabolism as the area may cool, so that they can survive.
where many other organisms might be killed off by that change. That's adaptation. Long-term changes in an organism that allow them to survive changes in the environment.
So these are some of the major characteristics of a living organism, and you should be able to list them and know them. Okay? Now... This leads us to some other things. We're talking about biology, the study of life and living organisms.
We were able to define some of the characteristics that determine if something's alive, and all living organisms exhibit some of these characteristics or some kind of characteristics. combination of them. But a few of the other terms that we need to discuss.
Now that we understand what life is and that we're studying life, what is microbiology? Well, microbiology is the study ...of organisms, and again, none of these definitions are perfect for every situation, okay? Because some of the stuff we're going to look at are not considered living organisms, like viruses and primates.
But nonetheless, it's the study of organisms that are too small to see with the naked eye. These are tiny little creatures that we cannot see with just plain old vision. We have to use a specialized instrument called a microscope in order to see them.
And the microscope is simply going to magnify something and resolve something so well that we can see it with our eyes. but we need a machine or a tool in order to see these organisms. Now, technically that's not 100% accurate. For number one, not everything I said a minute ago, not everything is a living organism like viruses and we're going to study them.
And also, some of the things we can see with the naked eye, because sometimes these microbial organisms will grow in a manner and in number that they become visible to the naked eye. Like one bacterium that you may not see, but as it divides and grows and grows and grows, it'll show up as a little colony or a plaque on a petri dish. And some of them grow and turn into fuzz, like the microbes that result in mold growing on your cheese at home if it's been sitting in the fridge too long.
So... So, some of the organisms eventually we could see with the naked eye, and actually there's a few organisms that we can see with the naked eye, but we study them using other techniques in microbiology, like staining and other types of microscopy, or other biochemical techniques in order to see them and understand them. So again, this is an imperfect definition, but ultimately that's what microbiology is. It's the study of microbes, which are things that are too small to see with the naked eye.
And that's another definition you should know. What is a microbe? Microbes are organisms too small to see.
with the unaided eye. And when I say naked eye, we can say also unaided eye. It doesn't have the aid of a visual scope or a tool that allows us to see it. So it's a group of organisms that are too small to see with the naked eye.
And one other term I need you to know is what we call the microbiome, also called the microbiota. The microbiome or the microbiota are those organisms that live on or in another organism. Usually an animal, but not always. Sometimes in plants as well.
So, for example, human beings have a microbiome. We have bacteria and things that grow on our skin and in our gut that actually provides a lot of benefit for us. They can prevent... parasites and fungi and other things from growing on us and some of the bacteria and the normal gut flora or the microbiome helps us break down some of the materials that we eat They produce vitamins that we absorb so same thing with cows and what we call ruminants certain organisms have bacteria that live in their gut that allow them to break down things like grasses and other types of plants and so we would call that the microbiome that group of organisms that live in another animal or organism that usually benefit it okay they provide a beneficial Well, they provide benefit for that organism. One of the things that we do know is that microbes can be very beneficial, but many of them can also be very harmful.
One thing we know about all of them is that they are ubiquitous. They are everywhere on earth that we go. Even at places where it was previously thought that... No life could exist here. We are finding living organisms.
And we're going to talk about some of those in a minute. But they're on our skin. They're in our hair.
They're inside our mouth. They're in our gut. They're in the urinary tract.
They're in the vagina. They're in the reproductive tract. They're on our skin.
on tables, everything that you touch, everywhere you go, there are microbes growing everywhere. As a matter of fact, it's estimated in some instances that there are more microbes growing on your skin than there are cells in the human body. Pretty hard to fathom, but in our skin and in our body, there's more microbes than the total number of cells in the human body.
That's crazy, but it's true. They're everywhere. So if you think you're going to get a perfectly sterile environment anywhere, it's extremely difficult. requires a lot of effort and energy to keep microbes out of an area, for example, like a surgical suite or out of the room with a patient. We'll talk about all that as time goes on, okay?
Now, so we know what life is or some characteristics of life. We know the definitions of biology, microbiology, the microbiome. One of the things we need to look at is like, what roles do microbes play in our life?
And sometimes if I step off camera, it's because I need to grab a drink. So please bear with me after lecturing the whole lot your throat gets a little raw. So if I take a pause and I'm off camera, forgive me.
All right, so what roles can microbes play in our lives? Well, one of the things we know is they impact human health both in a beneficial way, but also in a detrimental way and that's many microbes cause the pathology or the diseases that we experience. So, what are the benefits of a microbe? They can aid in the natural balance in nature.
So a lot of times microbes are breaking down a lot of the stuff like the leaves and things that fall on the jungle floor and other plants and animals as they die. They get digested and broken down or even things in the ocean are broken down by some of the microbes there. And some of the waste products and the microbes themselves are consumed by other organisms. And so they can help us balance out things in nature. There is a bunch of environmental uses.
One of the things that we call is bioremediation. This is where we use microbes to break down things. There are certain microbes that are being studied that break down plastics, so that if we threw a whole bunch of plastic waste in a particular landfill, maybe if we introduce these microbes, they'll break down the plastics much faster than they would over time, over centuries. Paper and other products, we can use microbes to break down a number of things. So they play a role.
and the natural balance of things and in helping balance out the environment. Another way that microbes play an important role in our life is through what we call fermentation or in food production. And one of the ways that they do so in food production is through fermentation.
Now, our cells convert oxygen and glucose into energy. And there's a complex biochemical pathway. But because many of the microbes, like bacteria, are so simple, bacteria... and yeast and other things can convert some of the sugar into other products like alcohol or vinegar and that results in the production of some of our alcoholic beverages and the vinegars and things that we use for cooking into some of the foods like mold like molds are used for certain cheeses and and yeast can help us produce some of the gases in bread make bread nice and tasty and fluffy and soft.
So they're used a lot in food production. Another way that we use microbes or how they impact our life is that there's industrial uses. For example, there's a compound that's produced called cellulose that microbes can help produce and also can help digest, by the way, other microbes.
But cellulose is used in a number of biological and environmental processes and in industrial use. They can generate a whole lot of chemicals that are used in industrial engineering, and so they play a huge role in industrial production. Also, some microbes can result in compounds that we use for pharmaceuticals, so they can be used for the production of medicines.
One of the roles they play is in what we call genetic engineering, where we can play with the DNA of a microbe and alter its DNA and make it produce something. Now, one way we do this is by using a microbe. that is in pharmaceutical production we can produce insulin now by using bacteria by splicing a gene for insulin into them growing them in a giant vat filtering off all the insulin putting it in a syringe for diabetics where many many years ago we just ground up the pancreas of a pig and try to isolate it and roughly 20 percent or more of the patients might have a reaction to the foreign type of insulin now we can eliminate that by producing human insulin from a human gene put into effect and they grow like crazy and produce tons of insulin.
So we use microbes in genetic engineering and biomedical engineering, recombinant DNA technology. We are using microbes for pharmaceutical production and other ways. Some of the bacteria, like penicillium, produces penicillin and they were discovered to produce the first antibiotics.
We use them in industrial uses and bioremedies. mediation, the natural balance of nature. So all of these myriad of ways we can use microbes. And a lot of these notes, by the way, if you're in my class, will be posted online.
They're also in the first chapter of your textbook. So now, why do we study microbiology? Well, if we understand how microbes work and what they're capable of, then we can use them for all these purposes.
One of the ways is for pharmaceutical production and genetic engineering. and industrial uses. So we study microbiology to help prevent, cure, and treat diseases, to understand the underlying causes of diseases. We use them for production of food, also to prevent food spoilage. If I understand that certain bacteria or certain microbes can cause food to rot and break down, well, how do I counteract that?
I can treat it with chemicals. or I can put it in a refrigerator, which slows the biochemical processes of that breakdown so that food lasts longer. So we can prevent food spoilage. We can increase food production. We can use it in industrial uses.
We can have, while some people are opposed to it, we can have genetically modified organisms like tomatoes or other crops, where we can modify them so that they're not easily attacked by other organisms that would eat the food or bacteria. other things that would cause the food to rot or break down. So we study microbiology for all these reasons, to prevent and cure diseases and treat illnesses, to understand the underlying causes of illnesses and diseases, to prevent food spoilage, and also to develop new technologies with recombinant DNA technology and all of this. Now, a lot of important terms and definitions are needed for us to understand in order to do well in microbiology, to understand everything we're going to be talking about. about this semester.
I'm going to provide some terminology now and I'm going to provide some as time goes on. So bear with me. These are some of the ones that you need to know for now.
So when we talk about cell, one of the things we need to know is that a cell is the smallest unit, or we should say the smallest living unit of an organism. And while it might require a lot of difficult technique, we can isolate some cells from an organism, put it in a dish, and they will exhibit all the characteristics, or many of the characteristics that we listed earlier, of a living organism. So... Another way to say this is, this is the smallest living unit of an organism that can perform all of the life processes, okay? And exhibits the characteristics of life.
Now, when it comes to cells, there's different types of cells. So when I talk about what's called a... Prokaryote.
P-R-O-K-A-R-Y-O-T-E. Prokaryote. Or if I say the term prokaryotic, it's referring to a prokaryote. Now, the karyo comes from this word. Karyon is apparently a Latin or Greek word, I think it's Latin, that means kernel.
Now when scientists first started studying cells under a microscope, they noticed that no matter what the shape of the cell, they always had this little dark spot, if we stained them properly, in the middle. They didn't know it was a nucleus, they didn't know what it was, so they called it the carotid. or the kernel, that little seed looking thing in the middle.
We now know that's a nucleus, and a nucleus will define what the organelles are and how they function a little bit later if you haven't done that already, or we're going to reiterate it if you've gone over it before. If carion means kernel or nucleus, then prokaryon means before a nucleus. So these are what are considered to be some of the older cells in life and some of the first cells to evolve.
We're called prokaryotes. Now, one way that we define prokaryotes is we define them as cells that lack a nucleus and other membrane-bound organelles. okay you have to pardon my back but as I teach this stuff I realized when I was a student I couldn't keep up with as fast as the instructor was going through powerpoint so the things that are important for you to know I'm going to write out on the board so that you also have time to write them so a prokaryote or prokaryotic you are cells that have, or I'm sorry, cells that lack a nucleus and other membrane-bound organelles. When we study cells in biology, you learn about the endoplasmic particulum, which has a membrane.
You learn about the nucleus, which has a nuclear envelope or a membrane. the Golgi apparatus, which has a membrane, and other types of membrane-bound organelles. Prokaryotes don't have a nucleus. They don't have a wall around their DNA to protect it.
They usually have a single chromosome with no nucleus. They have a few ribosomes and a lot of cytoplasm. And that's about it.
They're essentially a cell membrane with a cell wall very often, some DNA, usually a single circular chromosome, and some ribosomes and some cytosol. And that's it. Okay.
Now, the opposite of a prokaryote is what we call a eukaryote. Let me erase that. U comes from the word true, pro means before. So before it had a nucleus, the ancient cells didn't have a nucleus, they were very, very simple. No membrane-bound organelles.
Eukaryote means a true nucleus. These are cells that have a nucleus and other membrane-bound organelles. All the cells we're going to talk about when we talk about living cells fall under one of these two categories.
They're either prokaryotic cells or they are eukaryotic cells or sometimes we say they're prokaryote or eukaryote. Prokaryotes don't have any more They have a single chromosome with no nucleus around it and some ribosomes and some cytoplasm. Where eukaryotes have Golgi apparatus and endoplasmic reticulum and other types of ribosomes and a nucleus.
mitochondria and all these other membrane bound organelles. Now that's really really huge. Now two other definitions that we can talk about sometimes we're going to talk about unicellular prokaryotes or unicellular eukaryotes.
Uni comes from the same word as uno which means one so these are one-celled organisms. The entire organism is made up of a single cell. The opposite of that would be multicellular organisms. When we talk about multicellular organisms, these are organisms that are made of or comprised of many cells. Like humans are multicellular.
Most bacteria are single-celled organisms, okay? Now, some additional definitions that we're going to talk about, okay? We're going to do a lot of definitions in the beginning, and I'm going to finish up with these definitions in a moment, and then we'll do another video.
on the history of microbiology and all this intro level stuff, okay? So, when we talk about unicellular and multicellular organisms and prokaryotes and eukaryotes, one of the things we talk about is their mode of reproduction. And there's two ways that organisms can reproduce.
There's what we call asexual reproduction. And I'm not going to write out the word reproduction, I'm just going to put repro on the board. But asexual reproduction is when you have a single parent You only need one.
You don't need the opposite gender or sex or another partner. But when a single parent reproduces without interaction with another organism. There is no egg or sperm, which we often refer to as gametes. They don't require any gametes, no egg or sperm to reproduce, okay.
So in sexual reproduction we need a sperm and an egg or the gametes to fuse together the male and the female. female gametes, okay? And a couple of ways that this happens is by what we call budding. For example, in yeast, some yeasts have the ability to bud, which means if I have a little yeast cell here, this yeast cell over time can start to package a whole bunch of its own stuff in this little bud, like its DNA and its organelles. And then over time, it will pinch that little ball off, and now I have two yeast cells.
So we call that budding. Another way that some organisms can divide is by what we call binary fission. And in this situation, an example of an organism that can do binary fission, by the way, is some bacteria.
and what you have is you have a bacteria with a single chromosome, no nucleus, just a single circular chromosome. What will happen is it will reproduce that single circular chromosome through DNA replication, and then it will split in two. It literally divides in two, and I have two identical clones, each with the same genetic information. So some organisms can bud, split off a little piece of themselves, it's going to grow into a whole new organism, and some organisms have the possibility of developing a new organism.
of undergoing binary fission. The opposite of asexual reproduction is going to be sexual reproduction. So I'm going to erase a bunch of this, and we're going to talk about sexual reproduction a little bit. Not in great detail. We do that in human anatomy and physiology.
But the basics are, in sexual reproduction... It requires the fusion of a male and female gamete. The male and female gametes, we'll take the word a out, of male and female gametes.
That would be the sperm from the male and the egg from the female must fuse together to form a complete organism. And you get some of the DNA. from the male parent and some of the DNA from the female parent and this results in a lot of genetic variation so it requires the interaction of two organisms to share the sperm and the egg there are two parents involved in this process usually although there's occasionally where a plan or two can make with itself but we're not going to worry about that so um the the advantage of asexual reproduction is it's very simple and these organisms can multiply rapidly under the appropriate conditions and increase in number from one to billions overnight like some bacteria the advantage now the the The disadvantage of asexual reproduction is that they are all genetic clones, and if they're all in a tight little community, and I have some chemical that can kill one, that chemical can wipe them all out and kill an entire colony of bacteria and kill them all.
Where in sexual reproduction, because we are mixing the DNA of two organisms, which is a combination of the DNA from the previous generations, we get these very complex changing mixtures of DNA, of genetic material. that may allow that if some Disease or chemical comes in and wipes out a whole segment of the population You might have one that has a unique set of genes and gene products some proteins that allow it to survive those changes To survive a toxin or survive an illness Some people have a natural immunity to certain illnesses because of their genetic makeup and that results from from sexual reproduction So again, the advantage of asexual reproduction is rapid reproduction to increase the number rapidly the disadvantage is they're genetic clones, so if one of them is susceptible to some other chemical or product in the universe, they are all susceptible to it. Asexual reproduction, the disadvantage is it's slow, you have to have the right partners. The advantage is it provides a lot of genetic variation to increase chances of survival under changing conditions.
Now, when we talk about two organisms, or when we talk about the offspring of two organisms, or of any organism. if they produce asexually, we're going to talk about what's called the genotype. And I think of this as the types of genes in the organism. But the genotype is the genetic makeup of an organism, which is really what genes... are found in its genome.
And we'll define what a genome is, but it's the entire genetic makeup of an organism, all the genetic information. But the genotype is what is the genetic makeup of an organism, or what genes does it contain in its DNA, or in its RNA, if it has an RNA genome, like we're going to learn. The phenotype is those genes.
Sorry, my penmanship's a little off. Those genes that are expressed in the organism... So when we talk about a genotype of an organism, we're talking about what genes does it contain. Not always are those genes expressed. The phenotype is what you see in the organism, which gene is expressed.
And this gets... This requires us to sort of go into some complex genetics, and I'm not going to do that now, but we also define this as the observable characteristics of an organism. What genes do we see being expressed?
Okay, for example, if you have a person that carries the gene, the allele, the specific version of a gene called an allele for blue eyes and brown eyes, because of the rules of... genetics and how genes are expressed and what we call dominance and recession, that person will express, their phenotype will be that they have brown eyes. The genotype would be is that they have the gene for brown and blue eyes. The blue eye gene is not expressed. It doesn't show up in the phenotype.
The genotype is what genes does it have. The phenotype is what genes are expressed do we see in the organism. Okay? So, I hope that makes sense.
Now, a couple of other terms that we're going to use. Okay? And I'm going to come back to some of these in the near future when we do another chapter. All right? But I'm going to try to tie this up and finish up our definitions now.
We're going to talk about... talk about a structure called a glycoprotein, okay? We're also going to talk about something called a proteoglycan.
Now, if you've had any biology or chemistry before, and I know that you, at least at Del Mar, you have to have freshman chemistry. When we talk about a glycoprotein and a proteoglycan, there is a difference between the two, okay? And if you look at the name glyco, it always refers to sugar or carbohydrate.
Gluco and glyco. Anytime we see something referring to gluco or glyco or glyca slash glyco, it's usually something to do with sugars or carbs. Sugars or carbohydrates. Anytime we see proteo, we're talking about proteins. Well, it turns out that there are...
There are some compounds that are made out of sugars and proteins. two categories. So a glycoprotein technically is defined as a protein containing glycans. Okay, now that's kind of obvious. That's why it's called a glycoprotein, but those glycans are carbohydrates.
that are associated with that protein in a chemical bond. So proteins that have sugars or carbohydrates are called proteoglycans, I'm sorry, called glycoproteins. Now the difference between that and a proteoglycan is in a proteoglycan, this is a subgroup of glycoproteins.
Okay, so these are glycoproteins, but they have a carbohydrate with an amino acid down to them. They have a bound amino acid to the sugar. Okay, um, alright, I'm sorry, I shouldn't even say amino acid.
You know, when I think about it, it really is an amino group bound to them. Okay, so a proteoglycan is a carbohydrate or glycan that has an amino group bound to it. So, when we're talking about an amino group, an amino group to a chemist, means anything that has this, an NH2 group associated with it.
A nitrogen and two hydrogens is called an amino group, and this would represent where it would be bound to some other molecule. So proteoglycans are... carbohydrates with an associated amino group. They are a type of glycoprotein, but there are glycoproteins where we have sugars and proteins associated with each other, where the sugar does not have an amino group associated with it.
It's just a sugar associated with a protein. I know that's a little confusing and very closely related, but nonetheless, those are two of the definitions that you need to know. Okay. So now I hope that at least you have some definitions under your belt. It's It's not the most fun thing to learn is just memorizing definitions, but these definitions are going to be essential for when we start talking about other topics.
The hard part about microbiology is sometimes I'm going to talk about a subject early on, and then later on we're going to make sense of it. But I wanted to get this list of definitions out. If you're enrolled in my class or pretty much any micro class across the U.S., a lot of these definitions are going to appear on your first exam.
So I suggest... you start learning these definitions, knowing what the words mean, so that in the future, when you see a specific word like genotype, you can picture, oh, it's the types of genes in an organism. When I say phenotype, you picture in your mind, oh, those are the genes that are being expressed, that we see expressed in the organism. So learn the definitions, practice them, and be able to master all this information. And you're only going to do it through repetition, repetition, repetition.
You can't memorize them all. So start with three or four and do them 15 times in a row until you can write the words in order and the definitions out. Then learn four more and see if you can do all eight and add four more so that you guys can learn all these definitions.
Know the definitions of life or at least the characteristics of a living organism. Know the difference between prokaryotic and eukaryotic cells. Know the definition of microbiology and microbiome and microbiota and genotype.
and phenotype, eukaryotic, prokaryotic, all these definitions. Start working on them, start burning them into your brain. Now I hope you had as much fun as I did and I hope that the future lectures are going to be even more fun than just memorizing definitions. Thanks for watching and I'll see you in the next video.