WHAT ARE MICROBES guide and lessons.pptx

guide and lessons

1. WHAT ARE MICROBES? JUN D CRUZ Institute of Biology ADENU

2. Microbiology Is the study of microorganisms (bacteria, fungi, protozoa, algae and viruses) Is about living cells and how they work Is about microbial diversity

3. Why study microbiology? Microorganisms are part of the human environment and are therefore important to human health Microbiology provides insight into life processes in all life forms

4. Why microorganisms are especially useful in research? Microorganisms have relatively simple structures Large numbers of microorganisms can be used in an experiment to obtain statistically reliable results at a reasonable cost Microorganisms reproduce quickly, they are especially useful for studies involving the transfer of genes

5. Protozoa are defined as single-celled eukaryotic organisms, that feed heterotrophically and exhibit diverse motility mechanisms. However, it is impossible to draw a line between unicellular animals (consumers), plants (producers) and fungi (decomposers) and it is customary to speak of the Protista as a separate kingdom of unicellular eukaryotes that embraces both heterotrophic protozoa and autotrophic algae.

6. Protozoan classification Flagellates (or Mastigophora) Amoebae (or Sarcodina) Sporozoans (or Sporozoa, Apicomplexa) Ciliates (or Ciliophora)

7. Microbial diversity Cell size Shape (morphology) Metabolic strategies Motility Mechanisms of cell division Developmental biology Adaptation to environmental extremes

8. P eptidoglycan Thin sheet composed of 2 sugar derivatives, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) and a small group of amino acids consisting of L-alanine, D-alanine, D-glutamic acid, and either lysine or diaminopimelic acid (DAP) → form repeating structure, the glycan tetrapeptide

9. Full strength of the structure is realized only when the sugar chains are cross-linked by amino acids G+ - as much as 90% of the cell wall is peptidoglycan; teichoic acid (acidic polysaccharide) is usually present in small amount; have several (up to 25) peptidoglycan layer G- -only about 10% of the cell wall is peptidoglycan; the majority of the wall consisting of the outer membrane

10. Porins and Periplasm Porins function as channels for the entrance and exit of hydrophilic low MW substances Periplasm contains several proteins: 1. hydrolytic enzymes 2. binding proteins 3. chemoreceptors

11. Bacterial Flagella Long, thin (about 20 nm) appendages Arrangements: polar, lophotrichous, peritrichous Not straight but helically shaped; show constant distance between 2 adjacent curves (wavelength)

12. Bacterial cell surface structures and cell inclusions Fimbriae and pili - structurally similar to flagella but are not involved in motility Fimbriae enable organisms to stick to surfaces including animal tissues, or to form pellicle or biofilms on surfaces Pili are generally longer than fimbriae; function as receptors, involved in the process of conjugation, and attachment to host tissues

13. Paracrystalline surface layers (S-layers) cell surface layer composed of 2-dimensional array of protein universal in Archaea; act as an external permeability barrier, allowing passages of low MW substances Glycocalyx polysaccharide-containing material lying outside the cell; varies in organisms and can contain glycoproteins, polysaccharides, including polyalcohols and amino sugars

14. Capsule- rigid layers organized in a tight matrix Slime layer- more easily deformed, does not exclude particles and is more difficult to see Functions: 1. attachment of certain pathogenic microorganisms to their hosts 2. protection against phagocytic cells

15. Gas Vesicles Gas-filled structures surrounded by the constituents of the cytoplasm Confer buoyancy on the cells; menas of motility Structure- spindle-shaped made of proteins; impermeable to water and solutes but permeable to most gases

16. Endospores Differentiated cells that are very resistant to heat and cannot be destroyed easily, even by harsh chemicals (eg. Bacillus and Clostridium ) Structure: exosporium, spore coats, cortex, core/spore protoplast Other properties: have Ca-dipicolinic acid complex, SASPs, dehydrated