Podcast
Questions and Answers
Who is recognized as the father of medical microbiology?
Who is recognized as the father of medical microbiology?
What is the term for the classification of organisms based on their evolutionary relationships?
What is the term for the classification of organisms based on their evolutionary relationships?
What classification system did Carl Linnaeus first establish?
What classification system did Carl Linnaeus first establish?
Which kingdom includes bacteria and cyanobacteria?
Which kingdom includes bacteria and cyanobacteria?
Signup and view all the answers
What significant change in classification did Haeckel introduce?
What significant change in classification did Haeckel introduce?
Signup and view all the answers
How do complex multicellular eukaryotes in the Plantae kingdom obtain their nutrients?
How do complex multicellular eukaryotes in the Plantae kingdom obtain their nutrients?
Signup and view all the answers
Which of the following is NOT one of the five kingdoms in Whittaker's classification system?
Which of the following is NOT one of the five kingdoms in Whittaker's classification system?
Signup and view all the answers
What distinguishes prokaryotic cells from eukaryotic cells in biological classification?
What distinguishes prokaryotic cells from eukaryotic cells in biological classification?
Signup and view all the answers
What significant contribution did Edward Jenner make to immunology?
What significant contribution did Edward Jenner make to immunology?
Signup and view all the answers
What method did Louis Pasteur use to demonstrate that microorganisms caused contamination in nutrient broth?
What method did Louis Pasteur use to demonstrate that microorganisms caused contamination in nutrient broth?
Signup and view all the answers
Which disease was NOT one of the vaccines developed by Louis Pasteur?
Which disease was NOT one of the vaccines developed by Louis Pasteur?
Signup and view all the answers
What technique did Joseph Lister introduce in surgery to reduce infections?
What technique did Joseph Lister introduce in surgery to reduce infections?
Signup and view all the answers
Robert Koch is known for proving which theory in microbiology?
Robert Koch is known for proving which theory in microbiology?
Signup and view all the answers
Which of the following concepts is most closely associated with the work of Louis Pasteur?
Which of the following concepts is most closely associated with the work of Louis Pasteur?
Signup and view all the answers
What was the primary method used by Robert Koch to isolate pure cultures of bacteria?
What was the primary method used by Robert Koch to isolate pure cultures of bacteria?
Signup and view all the answers
What was one of the outcomes of Spallanzani's experiments on broth?
What was one of the outcomes of Spallanzani's experiments on broth?
Signup and view all the answers
What distinguishes Gram positive bacteria from Gram negative bacteria regarding their cell wall structure?
What distinguishes Gram positive bacteria from Gram negative bacteria regarding their cell wall structure?
Signup and view all the answers
Which component is absent in Gram negative bacteria?
Which component is absent in Gram negative bacteria?
Signup and view all the answers
What is the result of completely removing the cell wall from a Gram positive bacterium?
What is the result of completely removing the cell wall from a Gram positive bacterium?
Signup and view all the answers
Which statement is true about the structure of Gram negative bacteria?
Which statement is true about the structure of Gram negative bacteria?
Signup and view all the answers
Which type of bacteria are L-forms associated with?
Which type of bacteria are L-forms associated with?
Signup and view all the answers
How would you describe the cytoplasmic membrane of bacteria?
How would you describe the cytoplasmic membrane of bacteria?
Signup and view all the answers
What is the role of mesosomes in bacterial cells?
What is the role of mesosomes in bacterial cells?
Signup and view all the answers
Which characteristic is typical of Gram negative bacteria compared to Gram positive bacteria?
Which characteristic is typical of Gram negative bacteria compared to Gram positive bacteria?
Signup and view all the answers
What occurs during generalized transduction?
What occurs during generalized transduction?
Signup and view all the answers
What is the role of sex pili in conjugation?
What is the role of sex pili in conjugation?
Signup and view all the answers
What characterizes an Hfr cell?
What characterizes an Hfr cell?
Signup and view all the answers
How is a conjugative plasmid different from a non-conjugative plasmid?
How is a conjugative plasmid different from a non-conjugative plasmid?
Signup and view all the answers
What is a characteristic of cryptic plasmids?
What is a characteristic of cryptic plasmids?
Signup and view all the answers
What does the term 'R factor' refer to?
What does the term 'R factor' refer to?
Signup and view all the answers
What is true about episomes?
What is true about episomes?
Signup and view all the answers
What defines non-conjugative plasmids?
What defines non-conjugative plasmids?
Signup and view all the answers
Which type of fungal structure is responsible for reproduction in moulds?
Which type of fungal structure is responsible for reproduction in moulds?
Signup and view all the answers
What characterizes dimorphic fungi?
What characterizes dimorphic fungi?
Signup and view all the answers
Which type of hyphae is characterized by the absence of cross walls?
Which type of hyphae is characterized by the absence of cross walls?
Signup and view all the answers
In moulds, hyphea are primarily responsible for which function?
In moulds, hyphea are primarily responsible for which function?
Signup and view all the answers
Which type of mycelium penetrates the surface of the medium to absorb nutrients?
Which type of mycelium penetrates the surface of the medium to absorb nutrients?
Signup and view all the answers
Which of the following regarding yeasts is true?
Which of the following regarding yeasts is true?
Signup and view all the answers
What type of structure do fertile mycelium bear?
What type of structure do fertile mycelium bear?
Signup and view all the answers
What type of fungi produces pseudohyphae?
What type of fungi produces pseudohyphae?
Signup and view all the answers
Study Notes
Vaccination
- Edward Jenner is considered the father of immunology.
- Jenner inoculated a boy named James with cowpox, after he recovered, Jenner inoculated him with the smallpox virus, and James did not get sick.
- Jenner first used the term "vaccine" for this treatment.
- Pasteur adopted the word vaccination to describe any immunization against any disease.
Spontaneous Generation
- Spallanzani boiled broth for an hour and concluded that air is essential for life, this helped to disprove spontaneous generation theory.
- Louis Pasteur disproved spontaneous generation using a swan-neck flask experiment.
- He sterilized broth in the flask and demonstrated that exposure to air contaminated the broth with microorganisms from dust particles.
Germ Theory of Disease
- Pasteur further proved the Germ Theory of Disease by demonstrating microorganisms caused fermentation— crucial for brewing and baking.
- He also solved the problem of rancid wines in French vineyards by developing sterile techniques and Pasteurization of milk and other food products.
Attenuation for Vaccines
- Pasteur also discovered the ability to attenuate (decrease virulence) cultures to create artificial vaccines.
- Pasteur developed vaccines for fowl cholera, anthrax, and rabies— notably using the rabies vaccine on a boy named Joseph Meister.
Antiseptic Surgery
- Joseph Lister introduced antiseptic surgery in 1867.
- He used carbolic acid on instruments, wounds, and dressings to reduce surgical mortality from bacterial infections.
- Lister was the first to isolate a pure culture of Bacterium lactis using serial dilution.
Robert Koch
- Robert Koch provided the first proof of Germ Theory of Disease using the B.anthracis organism.
- He cultivated Anthrax bacteria outside the body using blood serum at body temperature.
- He developed techniques for growing bacteria on solid media (agar plates).
Classification of Microorganisms
- Classification: systematically arranging units of study into groups of larger units.
- Taxonomy: the science of classifying living organisms.
- Phylogenetic classification groups reflect organisms' genetic similarities and evolutionary relationships.
- Phylogeny is not synonymous with taxonomy.
- Taxonomy focuses on classifying existing species, while phylogeny traces species' evolutionary history.
Two-Kingdom System
- Carlluslinnoeus originally proposed the two-kingdom system, classifying organisms as either plants or animals.
Three-Kingdom System
- Haeckel added a third kingdom—Protista— to include unicellular microorganisms (bacteria, fungi, algae, and protozoa) that were neither plant nor animal.
Five-Kingdom System
-
Whittaker created a five-kingdom system based on nutritional requirements:
- Monera: (Bacteria and cyanobacteria) Originally classified as plants due to cell walls.
- Protista: (Algae, slime molds, protozoa) Have cell walls but not cellulose.
- Fungi: (Fungi, yeast, mold, mushrooms) Historically classified as plants due to cell walls and "rooted" nature.
- Plantae: Complex multicellular eukaryotes that obtain nutrients through photosynthesis.
- Animalia: Complex multicellular eukaryotes that obtain food by ingestion.
Eukaryotic and Prokaryotic Cells
- Later, electron microscopy studies divided cells into two groups: prokaryotic cells (bacteria) and eukaryotic cells (fungi, algae, and protozoa).
Gram-Positive and Gram-Negative Bacteria
- Differences between Gram-positive and Gram-negative bacteria:
| Feature | Gram-positive | Gram-negative |
|---|---|---|
| Structure | Simple | Complex |
| Thickness | Thicker | Thinner |
| Amino Acids | Few | Several |
| Lipid | Absent/Scant | Present |
| Teichoic acid | Present | Absent |
| Periplasmic Space | Absent | Present |
Cell Lysis and Wall Deficient Forms
- Removal of the cell wall leads to cell lysis due to osmotic pressure.
- Protoplasts: complete removal of the cell wall in Gram-positive bacteria results in a protoplast, which lyses without osmotic stability.
- Spheroplasts: Partial removal of the cell wall in Gram-negative bacteria results in a spheroplast with damaged cell walls.
- L-forms: Wall-less organisms or cell wall deficient forms of bacteria. They lack a regular size and shape, exhibiting pleomorphism. Mycoplasma naturally lacks peptidoglycan.
Cytoplasmic Membrane/Cell Membrane
-
The cytoplasmic membrane is a thin, elastic, semipermeable layer situated beneath the cell wall, separating it from the cytoplasm.
-
Key features of the cytoplasmic membrane:
- Exhibits selective permeability.
- Houses the electron transport system, the primary energy system in bacteria.
- Mesosomes, complex invaginations of the membrane, are present in many bacteria.
- Anchors and separates daughter chromosomes during cell division.
- The primary site for respiratory enzymes, analogous to mitochondria.
Cytoplasmic Components
- The cytoplasm contains DNA, ribosomes, storage granules, and a viscous aqueous solution.
Bacterial DNA
- Lack a nuclear membrane.
- Concentrated in the cytoplasm as a nucleoid— a single, long, double-stranded, circular, coiled DNA molecule.
- Bacterial DNA is haploid.
- Feulgen staining is used to visualize it under a light microscope.
Plasmids/Episomes
- Some bacteria contain extrachromosomal genetic material in the cytoplasm in the form of circular DNA called plasmids.
- Episomes: Plasmids that can integrate into the bacterial chromosome— F factor is an example.
Horizontal Gene Transfer: Transduction, Conjugation, Transformation
-
Transduction: Transfer of genetic material from one bacterium to another via bacteriophages (viruses that infect bacteria).
- Generalized Transduction: All bacterial DNA fragments have a chance to enter the phage.
- Specialized Transduction: Specific DNA fragments are transferred.
-
Conjugation: Transfer of DNA between bacteria through direct contact— discovered in 1946 by Lederberg and Tatum.
- Donor cells (male) contain an extrachromosomal sex factor or F factor.
- Recipient cells (female) lack the F factor.
- Sex pili bind to the recipient cell and retract it towards the donor cell. They act as tubes for DNA transfer.
- The donor replicates its sex factor, and one copy is transferred to the recipient.
- The recipient cell becomes F+ and can now act as a donor cell.
-
Hfr (Highly Frequency Recombination): A bacterial strain that has incorporated an F factor into its chromosome, allowing chromosome transfer during conjugation.
Plasmids
- Double-stranded, closed circular DNA molecules capable of autonomous replication.
- One exception is the linear plasmid in Borreliaburgdorferi.
- Episomes: Plasmids that can integrate into the bacterial chromosome.
- Conjugative Plasmids: Can mediate their own transfer to a new strain.
- Non-conjugative Plasmids: Cannot mediate their own transfer to a new strain.
- Cryptic Plasmids: Have no identifiable function besides self-replication.
- Resistance Plasmids (R Factors): Provide resistance to drugs— a single R factor may carry resistance to multiple drugs.
Classification of Fungi
-
Molds (Molds): Filamentous fungi, for example: Aspergillus spp, Trichophyton rubrum
-
Yeasts: Single-celled fungi that reproduce by budding, for example: Cryptococcus neoformans, Saccharomyces cerevisiae
-
Yeast-like Fungi: Similar to yeasts but produce pseudohyphae. For example: Candida albicans
-
Dimorphic Fungi: Can exist in two different morphological forms depending on environmental conditions:
- Yeast form: in tissues and in vitro at 37°C.
- Mold form: in their natural habitat and in vitro at 25°C. For example: Histoplasma capsulatum and Coccidioides immitis
Moulds
- The fungal body is called the thallus.
- Molds' thallus consists of a mycelium and spores.
- Spores are the basic reproductive unit of fungi.
- Spore germination produces microscopic thread-like structures called hyphae.
Hyphae
- Hyphae are thin, transparent, cylindrical tubes.
-
Two types of hyphae:
-
Nonseptate/Aseptate/Coenocytic Hyphae: Lack cross partitions, for example: Mucor and Rhizopus.
- Coenocytic hyphae are fungal filaments that lack septa, remaining multinucleate.
- Septate Hyphae: Protoplasm is divided by cross walls (septa) into numerous cells. Septate hyphae cells can be single nuclei or multinucleate.
-
Nonseptate/Aseptate/Coenocytic Hyphae: Lack cross partitions, for example: Mucor and Rhizopus.
Mycelium
-
Branching hyphae form a network called mycelium.
-
Mycelium contributes to colony color, texture, and topography.
-
Types of Mycelium:
- Vegetative Mycelium: Penetrates the medium's surface and absorbs nutrients.
- Aerial Mycelium: Grows above the agar surface.
- Fertile Mycelium: Aerial hyphae that bear reproductive structures—conidia or sporangia.
Yeasts
- Unicellular fungi— spherical, oval, or cylindrical cells.
- Reproduce by budding.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
