Ls2 afet unit 1 microorganisms
2 likes819 views
This document provides an overview of microorganisms and their classification. It discusses viruses, bacteria, fungi, protists and how they are classified. Key points include: - Microorganisms are very small life forms that are studied in microbiology. They include viruses, bacteria, fungi and protists. - Viruses consist of nucleic acid surrounded by a protein capsid, with some having an envelope. They replicate through lytic and lysogenic cycles. - Bacteria are classified by shape and reproduction. They have important roles in industry, disease and ecology. - Fungi absorb nutrients and can reproduce sexually or asexually. Examples include yeasts, molds and mushrooms.
Ls2 afet unit 1 microorganisms
- 1. UNIT 1: BIODIVERSITY AND THE CLASSIFICATION OF MICRO- ORGANISMS (Campbell and Reece (2010), Chapter 19, 6 p. 98, 28, 31, 43)
- 2. MICRO ORGANISMS Microorganisms are very small life forms (ultramicroscopic) Microscope examination Microbiology: The study of micro- organisms and their interactions with the environment and other life forms.
- 3. IMPORTANT MICROORGANISMS: Groups: VIRUSES BACTERIA FUNGI PROTISTA
- 4. VIRUSES Are “substances” that cause diseases and can be transmitted between organisms. Acellular????? Obligated intracellular parasites?? Outside the host – virus metabolically inert.
- 5. All virus particles consist of two parts : a central core of a nucleic acid strand (DNA/RNA) surrounded by a protein covering called a capsid. nucleocapsid
- 6. Some viruses - additional covering external to the capsid – called the envelope Virus with envelope - enveloped viruses and those without it = naked viruses. Envelope can have accessory structures.
- 7. The capsid consist of sub-units called capsomeres. The capsomeres have perfect geometric shapes. Depending on the shape and arrangement of these capsomeres, two types of capsids may be identified, namely helical and Icosahedral capsids
- 8. Helical and Icosahedral capsids
- 9. What criteria are used to classify a virus? geometry of the virus, whether they have envelopes the identity of the organism they infect transmission mode the disease they cause the type of nucleic acid.
- 10. Patterns of viral replication 1. The lytic cycle. Viruses enter a cell, replicate, and then cause the cell to burst, releasing new viruses. 2. The lysogenic cycle. Viruses enter a long term relationship with their host cells. Their nucleic acid replicates as the host cells multiply. D:Chapter_19A_PowerPoint_Lectures19_Lecture_Presentation1906LysogenicLyticCyclesA.ht ml
- 12. DIFFERENCE BETWEEN LYTIC AND LYSOGENIC CYCLES
- 13. The replication cycle of a bacteriophage (T4) • Bacteriophage: A virus that attacks bacteria cells.
- 14. HIV • Retroviruses use reverse transcriptase to copy their RNA genome into DNA • HIV (human immunodeficiency virus) is the retrovirus that causes AIDS (acquired immunodeficiency syndrome)
- 15. HIV REPRODUCTION
- 16. BACTERIA • Microscopic, unicellular prokaryote????. • Most are heterotrophic but some are capable to photosynthesize. • With respect to their oxygen requirement – 3 types: aerobic ( need oxygen to survive) facultative (can survive with or without oxygen) anaerobic (oxygen will kill these bacteria).
- 17. Structure of a bacterial cell • Flagellum: motility of cell • Pili:help with conjugation • Cell envelope: consist of the glycocalyx, cell wall and plasma membrane – protection • Slime capsule: protect against loss of water and stomach/soil acids. • Cell wall: consist of peptidoglycan – maintain shape of cell. • Plasma membrane: selective barrier that allows oxygen, nutrients and wastes through cell. • Nucleoid: consist of DNA - form chromatic bodies/plasmids. Genetic information for reproduction. • Ribosomes: complexes that make proteins (rRNA)
- 19. Bacteria are classified according to their shape and arrangement
- 20. Reproduction and life cycle of bacteria • They reproduce asexually by : budding and/or simple binary fission • There is no mitosis. • They generally gave a single chromosome. • Genetic exchange may occur through conjugation.
- 21. Budding of bacteria. • Cell's genetic information is duplicated, creating an identical copy or clone of the original cell. • As the new cell pinches off or buds from the surface, a bud scar is produced.
- 22. Binary fission of bacteria
- 23. IMPORTANCE OF BACTERIA ECONOMICALLY • Sulphur oxidizing bacteria can break down copper sulphide into copper sulphate for copper oar mining. • Fermentation bacteria is used to produce cheese, yogurt, buttermilk….. • Lactobacillus is used to make cheese. • Vinegar is made when wine/cider is fermented by acetic acid bacteria.
- 24. IMPORTANCE OF BACTERIA AS PATHOGENS CAUSE DISEASES SUCH AS: • Diphtheria: Bacteria affecting the pharynx – transmitted through coughing or sneezing. • Tuberculosis: Bacteria that attack the lungs – transmitted through saliva • Plague: Bacteria that infects the lymph nodes – transmitted to man from flee bites (flees come from rodents).
- 25. IMPORTANCE OF BACTERIA ECOLOGICALLY • Bacteria form part of the nitrogen cycle (denitrifying -, nitrifying – and nitrogen-fixed bacteria) • Bacteria are also involved in the sulfur and phosphorous cycles. • Bacteria act as saprophytes – break down complex organic molecules into simple inorganic molecules. • In rural areas bacteria is used in septic tanks to help to dispose of sewage.
- 26. FUNGI (MYCOPHYTA) • Fungi include moulds, mushrooms, yeast and mutualistic organisms. • Fungi are divided into macroscopic fungi and microscopic fungi. • Fungi are heterotrophs, but cannot ingest their food, they absorb nutrients from the environment outside of its body. They secrete enzymes into their surrounding environment which digests the food before absorption
- 28. FUNGI STRUCTURE • Fungi have vegetative filaments called hyphae, with or without cross walls/septa. • Hyphae cell walls consist of fungal chitin, surrounding a plasma membrane and cytoplasm. • The hyphae form an interwoven mass called the mycelium which infiltrates the medium on which it grows/lives. • Coenocytic fungi have continuous cytoplasmic masses with several nuclei.
- 29. FUNGI EXAMPLE: Rhizopus stolonifer Kollumella
- 30. The hyphae can be named specifically according to where they grow: • Rhizoids penetrate the substrate, • the stolon grows on the surface of the substrate and • the sporangiophore grows upright and contains the sporangium which contains the spores for asexual reproduction.
- 31. Reproduction of fungi Fungi can reproduce asexually (during favourable conditions) or sexually (during unfavourable conditions). We will study the reproduction of the bread mould: Rhizopus stolonifer ( Class Zygomycetes)
- 33. PROTISTA Protists: • are unicellular (one cell) • are Eukaryotes ( have a definite nucleus and membrane-bound organelles) • all are surrounded by a cell membrane. • Can move by means of flagella (Euglena, Trypanosoma), cilia (Paramecium) or pseudopodia (Amoeba) • (most) have a contractile vacuole – stores water and nutrients + involved in osmoregulation. • Form a food vacuole after the intake of food. • Are filled with cytoplasm: ectoplasm + endoplasm.
- 34. PROTISTA Protists: • Can feed: • autotrophic (photosynthesize) • Heterotrophic (depend on other organisms for food) • Or parasitic (feed on living organic material) Gaseous exchange occurs through the cell membrane – oxygen diffuse in the cell and carbon dioxide diffuse out of the cell.
- 35. PROTOZOA (SUBKINGDOM OF PROTISTA) Protozoa take in food by means of: 1. Phagocytosis: The process whereby pseudopodia are formed around a food particle, together with water and lysosomes to form a food vacuole. The lysosomes secrete hydrolytic enzymes to digest the food. 2. Pinocytosis: small particles are brought into the cell—forming an invagination, and then suspended within small vesicles that subsequently fuse with lysosomes to hydrolyze, or to break down, the particles
- 36. PROTOZOA Protozoa take in food by means of: PHAGOCYTOSIS
- 37. Reproduction: Sexual: Types of gametes 1) Isogametes – one of a pair of gametes that are morphologically the same 2) Anisogametes – gametes that are morphologically different e.g. sperm and egg 3) Microgametes – male gametes 4) Macrogametes – female gametes
- 38. Reproduction: Sexual 1. Conjugation * Exchange of gametic nuclei * Exchange of genetic material 2) Syngamy: * Fusion of anisogametes (sperm & egg) 3) Autogamy * Fusion of haploid nuclei from the same individual * Fusion of isogametes
- 39. Protista is classified in the following way:
- 41. Euglena – classification and traits Kingdom: Protista Subkingdom: Protozoa Phylum: Sarcomastigophora Subphylum: Mastigophora Class: Phytomastigophorea (e.g. Genus:Euglena Characteristics: * Have one/two flagella * Have a spiral / crystalline rod inside flagella * Cytoskeleton * Autotrophs in sunlight and heterotrophs in the dark engulfing food by phagocytosis
- 42. Long flagellum Eyespot Short flagellum Contractile vacuole Nucleus Chloroplast Plasma membrane Light detector Pellicle Euglena (LM) 5 µm Euglena
- 43. Classification and traits of Trypanosoma Kingdom: Protista Subkingdom: Protozoa Phylum: Sarcomastigophora Subphylum: Mastigophora Class: Zoomastigophorea Genus: Trypanosoma Characteristics: Cause African sleeping sickness in humans
- 44. Classification and traits of Trichomonas Kingdom: Protista Subkingdom: Protozoa Phylum: Sarcomastigophora Subphylum: Mastigophora Class: Zoomastigophorea Genus: Trichomonas Characteristics: Pathogen causing severe infection in human females called vaginitis
- 45. Classification and traits of Amoeba Kingdom: Protista Subkingdom: Protozoa Phylum : Sarcomastigophora Subphylum: Sarcodina Genus: Amoeba Characteristics * Fleshly Pseudopodia
- 46. Classification and traits of Plasmodium Kingdom: Protista Subkingdom: Protozoa Phylum : Apicomplexa Class: Sporozoea Genus: Plasmodium Characteristics * Parasite that cause malaria in humans (primary host) – mosquito’s are the intermediate hosts. * One end, the apex, contains a complex of organelles specialized for penetrating a host * Have complex life cycle with asexual and sexual stages which require two or more different hosts for completion
- 47. Life cycle of Plasmodium
- 48. Classification and traits of Paramecium Kingdom: Protista Subkingdom: Protozoa Phylum: Ciliophora Genus: Paramecium Characteristics: * Contains cillia * Binucleated (micro and macronucleus) * Asexual reproduction by binary fission
- 49. SYMBIOTIC RELATIONSHIPS OF MICROORGANISMS WITH PLANTS Plants have mutualistic relationships with several groups of bacteria that help make nitrogen more available. 3 types of bacteria are important: 1. Nitrogen-fixing bacteria: converts atmospheric nitrogen into ammonia which in the soil binds with a hydrogen ion to for ammonium. 2. Ammonifying bacteria: decompose protein into ammonia which in the soil binds with a hydrogen ion to for ammonium. 3. Nitrifying bacteria: converts ammonium into nitrates which can be absorbed by plants.
- 50. SYMBIOTIC RELATIONSHIPS OF E. coli IN THE HUMAN BODY Escherichia coli commonly abbreviated E. coli It is a gram negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K and by preventing the establishment of pathogenic bacteria within the intestine
- 51. E.coli found in the human colon
- 52. DISEASES CAUSED BY MICROORGANISMS Do research on the following diseases: • HIV – viral disease • Tuberculosis – bacterial disease • Malaria – protista disease • Thrush – fungal disease
- 53. WHAT SOULD I KNOW ABOUT THE DISEASES? The genus name of the organism that causes the disease, the symptoms of the disease, what part of the body is affected by the disease possible treatment for the disease. You do not have to hand this in, but there will be questions in the exam and tests on it.