LECTURE 1 Flashcards
What is Microbiology?
A great complex of biological sciences about micro-organisms
What are the major groups of microorganisms?
- Bacteria
- Archaea
- Fungi
- Algae
- Protozoa
- Viruses
What are the different types of Human pathogens?
SUBCELLULAR BIOLOGICAL ENTITIES:
- Prions (infection proteins)
- Viruses
PROKARYOTIC MICROORGANISMS:
- Chlamydiae
- Rickettsiae
- Mycoplasmas
- Classic bacteria
EUKARYOTIC MICROORGANISMS:
- Fungi
- Protozoa
ANIMALS:
- Helminths
- Arthropods
What did Antony van Leeuwenhoek do?
- First person who observed and described microorganisms
- Constructed first microscope (magnification 50-300X)
What did Louis Pasteur do?
- Established that fermentation was the result of microbial activity
- Introduced techniques of sterilisation
- Showed that microorganisms DO NOT arise by spontaneous generation
- Elaborated methods of pathogenic microorganisms attenuation
- Developed rabies vaccine and anthrax one
What are the key concepts of Koch’s postulates?
- A specific infectious disease is caused by a specific microbe
- Postulates help determine the ETIOLOGY of disease (first step in treatment + prevention)
What did Robert Koch do?
- Elaborated methods of staining and cultivation of microorganisms
- Discovered what caused anthrax, cholera and tubercle bacillus
- Proposed techniques for pure culture isolation
- Elaborated criteria for proving relationship between a microorganism and specific diseases (Koch’s postulates)
What are Koch’s postulates?
- Microorganisms must be present in every case of the disease but absent in healthy organism
- Suspected microorganism must be isolated and grown in pure culture
- Same disease must result when the isolated microorganism is inoculated into a healthy host
- Same microorganism must be isolated again from the diseased host
What are the different characteristics of the different Bacterial forms?
- COCCI: occur in clusters, chains, pairs and packets
- STRAIGHT RODS: uniform thickness, rounded/pointed ends
- CURVED RODS: comma shaped, spiral, screw shaped
- MYCOPLASMAS: bacteria without a rigid cell wall, coccoid cells, long threads
- CHLAMYDIAE: either spherical/oval elementary bodies or spherical/oval reticulate bodies
- RICKETTSIAE: short coccoid rods
Which structures are found in all bacteria?
- Plasma membrane
- Cytoplasm
- 70S Ribosomes
- Nucleoid containing DNA
____________ of bacterial flagella propel the cell through an aqueous environment
Rotation
What is the difference between a Nucleoid and a Plasmid?
Nucleoid = Double-stranded DNA localised in the cytoplasm
Plasmid = Genetic structure with circular DNA
Describe the formation of endospores by sporulation
1) Spore septum isolates newly replicated DNA and a small portion of cytoplasm + Plasma membrane surrounds isolated DNA and cytoplasm
2) Spore septum surrounds isolated portion forming FORESPORE
3) Petidoglycan layer forms between membranes, spore coat forms and Endospore is freed from cell
What does the cytoplasm contain?
- A large number of solute low and high molecular weight substances
- RNA
- 20000 ribosomes
- Reserve substances (e.g glycogen depots, polymerised metaphosphate, lipids)
Bacteria have _____ ribosomes comprising 30S and 50S subunits
70S
What are the Bacterial cell wall functions?
- Protect the PROTOPLASTS from EXTERNAL NOXAE
- Withstand and maintain the osmotic pressure gradient between the cell interior and the extracellular environment
- Give cell its outer form + facilitate communication with its surroundings
What gives the bacterial cell wall its strength?
A layer composed of a substance referred to as Murein, Mucopeptide or Peptidoglycan
Explanation: Consists of repeating units of N-ACETYLGLUCOSAMINE (NAG) and N-ACETYLMURAMIC ACID (NAM) crossed linked by peptide side chains. PENICILLIN-BINDING PROTEINS (PBP) cross-link these peptide side chains
What are the characteristics of Gram-positive bacteria?
- Thick murein layer
- Proteins and trichroic acids anchored in the murrain
- Lipoteichoic acid fixed to membrane by lipophilic anchor
- No Porin proteins or Periplasm
- More sensitive to penicillin and lysozyme