Unit 1 microorganisms students
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The document provides an overview of microorganisms, focusing on viruses and bacteria, their structure, classification, and life cycles. It explains virus replication processes (lytic and lysogenic) and details on bacteriophages, as well as the structure and reproduction of bacteria. Additionally, the document highlights the economic, pathogenic, and ecological importance of bacteria.
Unit 1 microorganisms students
- 1. Micro-organisms: virus and bacterius Grade 11 By Obey Maduna
- 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 • Pilli: 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.