In this video, we're going to begin our lesson on the members of the microbial world. And so there's actually a massive variety of microbes that exist within the microbial world. All of this variety is due to the fact that these microbes have been around for 1,000,000,000 of years, which is a really, really long time allowing them to develop and evolve in many different ways, leading to this massive variety. Now these microbes, as we discussed in some of our previous lesson videos, they can either be living organisms that are made of cells or they can be nonliving acellular infectious agents such as viruses, for example. And so by the term acellular, really what we mean is that they are not made of cells. And so microbes can either be living and made of cells or they can be nonliving and acellular, not made of cells. And we'll be able to see that down below in our image when we get there. Now these living organisms that are made of cells, they can either be prokaryotic, such as bacteria and archaea, or they can be eukaryotic, such as fungi, for example. And so if we take a look at our image down below at this map of the microbial world, what you'll notice is that this is an image that you can actually use as a map of our lesson on the microbial world. And so you can see at the very top, we have the microbial world, and it branches into two major groups. It branches into cellular organisms that are actually living and made of cells, and it also branches into acellular infectious agents that are acellular and not made of cells. And so as we move forward in our lesson, we are going to explore this map by following the leftmost branches first, and we'll continue to do that and zoom out as we go through our lesson. And so we'll cover the cellular organisms first, and then once we finish covering the cellular organisms, we'll zoom back out and talk about the acellular infectious agents. And so you can see, you can use this image as a reference and as a map of our lesson moving forward. And so what you can see here is that these cellular organisms, they can be branched into either prokaryotic organisms or prokaryotes or eukaryotic organisms or eukaryotes. Now notice that microbiologists will specifically focus on eukaryotes that are microscopic, microscopic eukaryotes. Now within this table, you can see that prokaryotes tend to be unicellular organisms made up of only one single cell. And prokaryotes do not have a nucleus, they have no nucleus. Whereas these eukaryotes that are over here, they can either be unicellular, again made of only one single cell, or they can be multicellular made up of many cells. And the eukaryotes, they do have a nucleus within the the cells. Now, looking at the prokaryotes over here, they branch into either bacteria or archaea. And moving forward, we'll be able to talk more about each of these different groups. Now notice that the eukarya over here, they can actually branch into many different groups, and not all of the groups are being shown here for the eukarya. However, what we are showing are the groups that microbiologists tend to focus on the most such as fungi, protists like algae and protozoa, and helminths. And so again, we'll be able to talk about each of these groups as we move forward in our course. Now for the acellular, infectious agents, they are grouped into three different categories, viruses, viroids, and prions. And once again, we'll be able to talk about each of these groups in more detail as we move forward in our course. However, this is a map of the microbial world that you should be familiar with and be able to group different, different groups under the appropriate label. So you should know that fungi, protists, and helminths are all part of the eukarya eukarya group and that viruses, viroids, and prions are part of the acellular infectious agents, and that the prokaryotes, would consist of bacteria and archaea. And so knowing those groupings will be important for you as you move forward in this course. Now, one thing to note is that the bacteria and archaea, which are over here listed under the prokaryotes, many students tend to think that bacteria and archaea are pretty much identical. However, it's important to note that bacteria and archaea are actually as different from each other as they are from the eukaryotes. And so although they are falling under the same branch of prokaryotes, they are very, very different from each other and they that is why they are into, these separate, domains is what they call them. And so again, as we move forward in our course, we'll be able to talk more and more about all of the, groups that are on this map. But for now, this here concludes our introduction to the members of the microbial world and I'll see you all in our next video.
- 1. Introduction to Microbiology3h 21m
- Introduction to Microbiology16m
- Introduction to Taxonomy26m
- Scientific Naming of Organisms9m
- Members of the Bacterial World10m
- Introduction to Bacteria9m
- Introduction to Archaea10m
- Introduction to Eukarya20m
- Acellular Infectious Agents: Viruses, Viroids & Prions19m
- Importance of Microorganisms20m
- Scientific Method27m
- Experimental DesignÂ30m
- 2. Disproving Spontaneous Generation1h 18m
- 3. Chemical Principles of Microbiology3h 38m
- 4. Water1h 28m
- 5. Molecules of Microbiology2h 23m
- 6. Cell Membrane & Transport3h 28m
- Cell Envelope & Biological Membranes12m
- Bacterial & Eukaryotic Cell Membranes8m
- Archaeal Cell Membranes18m
- Types of Membrane Proteins8m
- Concentration Gradients and Diffusion9m
- Introduction to Membrane Transport14m
- Passive vs. Active Transport13m
- Osmosis33m
- Simple and Facilitated Diffusion17m
- Active Transport30m
- ABC Transporters11m
- Group Translocation7m
- Types of Small Molecule Transport Review9m
- Endocytosis and Exocytosis15m
- 7. Prokaryotic Cell Structures & Functions5h 52m
- Prokaryotic & Eukaryotic Cells26m
- Binary Fission11m
- Generation Times16m
- Bacterial Cell Morphology & Arrangements35m
- Overview of Prokaryotic Cell Structure10m
- Introduction to Bacterial Cell Walls26m
- Gram-Positive Cell Walls11m
- Gram-Negative Cell Walls20m
- Gram-Positive vs. Gram-Negative Cell Walls11m
- The Glycocalyx: Capsules & Slime Layers12m
- Introduction to Biofilms6m
- Pili18m
- Fimbriae & Hami7m
- Introduction to Prokaryotic Flagella12m
- Prokaryotic Flagellar Structure18m
- Prokaryotic Flagellar Movement11m
- Proton Motive Force Drives Flagellar Motility5m
- Chemotaxis14m
- Review of Prokaryotic Surface Structures8m
- Prokaryotic Ribosomes16m
- Introduction to Bacterial Plasmids13m
- Cell Inclusions9m
- Endospores16m
- Sporulation5m
- Germination5m
- 8. Eukaryotic Cell Structures & Functions2h 18m
- 9. Microscopes2h 46m
- Introduction to Microscopes8m
- Magnification, Resolution, & Contrast10m
- Introduction to Light Microscopy5m
- Light Microscopy: Bright-Field Microscopes23m
- Light Microscopes that Increase Contrast16m
- Light Microscopes that Detect Fluorescence16m
- Electron Microscopes14m
- Reviewing the Different Types of Microscopes10m
- Introduction to Staining5m
- Simple Staining14m
- Differential Staining6m
- Other Types of Staining11m
- Reviewing the Types of Staining8m
- Gram Stain13m
- 10. Dynamics of Microbial Growth4h 36m
- Biofilms16m
- Growing a Pure Culture5m
- Microbial Growth Curves in a Closed System21m
- Temperature Requirements for Microbial Growth18m
- Oxygen Requirements for Microbial Growth22m
- pH Requirements for Microbial Growth8m
- Osmolarity Factors for Microbial Growth14m
- Reviewing the Environmental Factors of Microbial Growth12m
- Nutritional Factors of Microbial Growth30m
- Growth Factors4m
- Introduction to Cultivating Microbial Growth5m
- Types of Solid Culture Media4m
- Plating Methods16m
- Measuring Growth by Direct Cell Counts9m
- Measuring Growth by Plate Counts14m
- Measuring Growth by Membrane Filtration6m
- Measuring Growth by Biomass15m
- Introduction to the Types of Culture Media5m
- Chemically Defined Media3m
- Complex Media4m
- Selective Media5m
- Differential Media9m
- Reducing Media4m
- Enrichment Media7m
- Reviewing the Types of Culture Media8m
- 11. Controlling Microbial Growth4h 10m
- Introduction to Controlling Microbial Growth29m
- Selecting a Method to Control Microbial Growth44m
- Physical Methods to Control Microbial Growth49m
- Review of Physical Methods to Control Microbial Growth7m
- Chemical Methods to Control Microbial Growth16m
- Chemicals Used to Control Microbial Growth6m
- Liquid Chemicals: Alcohols, Aldehydes, & Biguanides15m
- Liquid Chemicals: Halogens12m
- Liquid Chemicals: Surface-Active Agents17m
- Other Types of Liquid Chemicals14m
- Chemical Gases: Ethylene Oxide, Ozone, & Formaldehyde13m
- Review of Chemicals Used to Control Microbial Growth11m
- Chemical Preservation of Perishable Products10m
- 12. Microbial Metabolism5h 16m
- Introduction to Energy15m
- Laws of Thermodynamics15m
- Chemical Reactions9m
- ATP20m
- Enzymes14m
- Enzyme Activation Energy9m
- Enzyme Binding Factors9m
- Enzyme Inhibition10m
- Introduction to Metabolism8m
- Negative & Positive Feedback7m
- Redox Reactions22m
- Introduction to Aerobic Cellular Respiration25m
- Types of Phosphorylation12m
- Glycolysis19m
- Entner-Doudoroff Pathway11m
- Pentose-Phosphate Pathway10m
- Pyruvate Oxidation8m
- Krebs Cycle16m
- Electron Transport Chain19m
- Chemiosmosis7m
- Review of Aerobic Cellular Respiration19m
- Fermentation & Anaerobic Respiration23m
- 13. Photosynthesis2h 31m
- 14. DNA Replication2h 25m
- 15. Central Dogma & Gene Regulation7h 14m
- Central Dogma7m
- Introduction to Transcription20m
- Steps of Transcription22m
- Transcription Termination in Prokaryotes7m
- Eukaryotic RNA Processing and Splicing20m
- Introduction to Types of RNA9m
- Genetic Code25m
- Introduction to Translation30m
- Steps of Translation23m
- Review of Transcription vs. Translation12m
- Prokaryotic Gene Expression21m
- Review of Prokaryotic vs. Eukaryotic Gene Expression13m
- Introduction to Regulation of Gene Expression13m
- Prokaryotic Gene Regulation via Operons27m
- The Lac Operon21m
- Glucose's Impact on Lac Operon25m
- The Trp Operon20m
- Review of the Lac Operon & Trp Operon11m
- Introduction to Eukaryotic Gene Regulation9m
- Eukaryotic Chromatin Modifications16m
- Eukaryotic Transcriptional Control22m
- Eukaryotic Post-Transcriptional Regulation28m
- Post-Translational Modification6m
- Eukaryotic Post-Translational Regulation13m
- 16. Microbial Genetics4h 44m
- Introduction to Microbial Genetics11m
- Introduction to Mutations20m
- Methods of Inducing Mutations15m
- Prototrophs vs. Auxotrophs13m
- Mutant Detection25m
- The Ames Test14m
- Introduction to DNA Repair5m
- DNA Repair Mechanisms37m
- Horizontal Gene Transfer18m
- Bacterial Transformation11m
- Transduction32m
- Introduction to Conjugation6m
- Conjugation: F Plasmids18m
- Conjugation: Hfr & F' Cells19m
- Genome Variability21m
- CRISPR CAS11m
- 17. Biotechnology3h 0m
- 18. Viruses, Viroids, & Prions4h 56m
- Introduction to Viruses20m
- Introduction to Bacteriophage Infections14m
- Bacteriophage: Lytic Phage Infections12m
- Bacteriophage: Lysogenic Phage Infections17m
- Bacteriophage: Filamentous Phage Infections8m
- Plaque Assays9m
- Introduction to Animal Virus Infections10m
- Animal Viruses: 1. Attachment to the Host Cell7m
- Animal Viruses: 2. Entry & Uncoating in the Host Cell19m
- Animal Viruses: 3. Synthesis & Replication22m
- Animal Viruses: DNA Virus Synthesis & Replication14m
- Animal Viruses: RNA Virus Synthesis & Replication22m
- Animal Viruses: Antigenic Drift vs. Antigenic Shift9m
- Animal Viruses: Reverse-Transcribing Virus Synthesis & Replication9m
- Animal Viruses: 4. Assembly Inside Host Cell8m
- Animal Viruses: 5. Release from Host Cell15m
- Acute vs. Persistent Viral Infections25m
- COVID-19 (SARS-CoV-2)14m
- Plant Viruses12m
- Viroids6m
- Prions13m
- 19. Innate Immunity7h 15m
- Introduction to Immunity8m
- Introduction to Innate Immunity17m
- Introduction to First-Line Defenses5m
- Physical Barriers in First-Line Defenses: Skin13m
- Physical Barriers in First-Line Defenses: Mucous Membrane9m
- First-Line Defenses: Chemical Barriers24m
- First-Line Defenses: Normal Microflora5m
- Introduction to Cells of the Immune System15m
- Cells of the Immune System: Granulocytes29m
- Cells of the Immune System: Agranulocytes25m
- Introduction to Cell Communication5m
- Cell Communication: Surface Receptors & Adhesion Molecules16m
- Cell Communication: Cytokines27m
- Pattern Recognition Receptors (PRRs)45m
- Introduction to the Complement System24m
- Activation Pathways of the Complement System23m
- Effects of the Complement System23m
- Review of the Complement System12m
- Phagoctytosis21m
- Introduction to Inflammation18m
- Steps of the Inflammatory Response26m
- Fever8m
- Interferon Response25m
- 20. Adaptive Immunity7h 14m
- Introduction to Adaptive Immunity32m
- Antigens12m
- Introduction to T Lymphocytes38m
- Major Histocompatibility Complex Molecules20m
- Activation of T Lymphocytes21m
- Functions of T Lymphocytes25m
- Review of Cytotoxic vs Helper T Cells13m
- Introduction to B Lymphocytes27m
- Antibodies14m
- Classes of Antibodies35m
- Outcomes of Antibody Binding to Antigen15m
- T Dependent & T Independent Antigens21m
- Clonal Selection20m
- Antibody Class Switching17m
- Affinity Maturation14m
- Primary and Secondary Response of Adaptive Immunity21m
- Immune Tolerance28m
- Regulatory T Cells10m
- Natural Killer Cells16m
- Review of Adaptive Immunity25m
- 21. Principles of Disease6h 57m
- Symbiotic Relationships12m
- The Human Microbiome46m
- Characteristics of Infectious Disease47m
- Stages of Infectious Disease Progression26m
- Koch's Postulates26m
- Molecular Koch's Postulates11m
- Bacterial Pathogenesis36m
- Introduction to Pathogenic Toxins6m
- Exotoxins Cause Damage to the Host40m
- Endotoxin Causes Damage to the Host13m
- Exotoxins vs. Endotoxin Review13m
- Immune Response Damage to the Host15m
- Introduction to Avoiding Host Defense Mechanisms8m
- 1) Hide Within Host Cells5m
- 2) Avoiding Phagocytosis31m
- 3) Surviving Inside Phagocytic Cells10m
- 4) Avoiding Complement System9m
- 5) Avoiding Antibodies25m
- Viruses Evade the Immune Response27m
Members of the Bacterial World - Online Tutor, Practice Problems & Exam Prep
The microbial world consists of diverse organisms, categorized into living cellular organisms and nonliving acellular infectious agents. Cellular organisms are further divided into prokaryotes, like bacteria and archaea, which lack a nucleus, and eukaryotes, such as fungi and protists, which possess a nucleus. Acellular agents include viruses, viroids, and prions. Understanding these classifications is crucial, as bacteria and archaea, while both prokaryotic, are fundamentally different. This knowledge lays the foundation for exploring microbial diversity and its implications in various fields, including microbiology and medicine.
Members of the Bacterial World
Video transcript
Which of the following groups is composed of prokaryotic organisms?
Which of the following groups is composed of eukaryotic organisms?
Which of the following groups is considered acellular?
Do you want more practice?
Here’s what students ask on this topic:
What are the main differences between prokaryotic and eukaryotic cells?
Prokaryotic cells, such as bacteria and archaea, lack a nucleus and membrane-bound organelles. They are generally unicellular and have a simpler structure. Their DNA is located in a nucleoid region. Eukaryotic cells, found in organisms like fungi and protists, have a defined nucleus containing their DNA and various membrane-bound organelles, such as mitochondria and the endoplasmic reticulum. Eukaryotic cells can be either unicellular or multicellular. These structural differences are crucial for their functions and roles in the microbial world.
How do viruses differ from bacteria in terms of structure and replication?
Viruses are acellular infectious agents, meaning they are not made of cells and lack cellular structures. They consist of genetic material (DNA or RNA) enclosed in a protein coat called a capsid. Some viruses also have an outer lipid envelope. Unlike bacteria, which are living prokaryotic cells that can reproduce independently through binary fission, viruses require a host cell to replicate. They hijack the host's cellular machinery to produce new viral particles, leading to the host cell's damage or death.
What are the three main types of acellular infectious agents?
The three main types of acellular infectious agents are viruses, viroids, and prions. Viruses consist of genetic material (DNA or RNA) enclosed in a protein coat. Viroids are small, circular RNA molecules that infect plants and do not encode proteins. Prions are misfolded proteins that can induce other proteins to misfold, leading to diseases such as Creutzfeldt-Jakob disease in humans. These agents are distinct from cellular organisms as they lack cellular structures and require a host for replication.
Why are bacteria and archaea considered fundamentally different despite both being prokaryotes?
Bacteria and archaea are considered fundamentally different due to significant differences in their genetic, biochemical, and structural characteristics. Bacteria have peptidoglycan in their cell walls, while archaea do not. Archaea have unique membrane lipids and their ribosomal RNA sequences differ significantly from those of bacteria. Additionally, archaea often thrive in extreme environments, such as high temperatures or high salinity, where most bacteria cannot survive. These differences justify their classification into separate domains.
What are the main groups of eukaryotic microorganisms studied in microbiology?
The main groups of eukaryotic microorganisms studied in microbiology include fungi, protists (such as algae and protozoa), and helminths. Fungi are important decomposers and can be unicellular (like yeasts) or multicellular (like molds). Protists are a diverse group that includes photosynthetic algae and heterotrophic protozoa. Helminths are parasitic worms that can cause diseases in humans and animals. These groups are studied for their ecological roles, pathogenic potential, and biotechnological applications.
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