Introduction to Medical Mycology and Virology

Human Biology Lecture 10

1. University of Duhok College of Health Sciences Dep. of Medical Laboratories Sciences Human Biology/1 st Stage Lecture 10 Dr.: Shameeran S. Ismael BVM & S, M.Sc Medical Microbiology( Parasitology ), PhD Molecular Parasitology

2. What is Mycology? Mycology is the branch of biology that deals with the study of fungi. It includes the research of their genetic and biochemical properties, and their use in medicine and food along with their hazards.

3. What is Fungi? Fungi are a kingdom of usually multicellular eukaryotic organisms that are heterotrophs (cannot make their own food).

4. General Properties of Fungi: • They are eukaryotic • Have a rigid cell wall made of chitin and are therefore non-motile • Typically reproduce asexually and/or sexually by producing spores. • Chemoheterotrophs (require organic compounds for both carbon and energy sources) • Fungi are osmotrophic

5. Beneficial Effects of Fungi Decomposition Important sources of antibiotics, such as Penicillin. Some fungi are edible (mushrooms). Some fungi are used in food production (Yeast)

6. Harmful Effects of Fungi Destruction of food, lumber, paper, and cloth Animal and human diseases, including allergies Plant diseases Spoilage of agriculture products such as vegetables

7. Classification of Fungi Fungi can be classified based on : 1. Sexual reproduction 2 . Morphology: Molds Yeast Dimorphic

8. Molds Molds are various types of fungi that grow multicellular filaments called hyphae and reproduce by forming spores that can travel through the air. Hyphae= the thread-like filaments that make up a multicellular fungus and release enzymes to absorb nutrients from food sources. Mycelium= Collection of Hyphae Found in: damp and dark areas

9. Yeast Yeasts are fungi that grow as single cells, producing daughter cells either by budding or by binary fission. Some species with yeast forms may become multicellular through the formation of a string of connected budding cells known as pseudohyphae Found in: Skin, foods, and in the digestive system of mammals

10. Dimorphic Fungi Dimorphic fungi are fungi that have a yeast phase and a mold phase depending on environmental conditions. In general, dimorphic fungi produce a mold form at 25-30°C and a yeast form at 35- 37°C

11. What is Virology? Virology is the bioscience of the study viral natures, in addition to the basic relationships between viruses and their hosts

12. Why virology ? Viruses infect all living things. We eat and breath billions of virus every day. We carry viral genome as our own genome Viruses can be use as a crucial genetic engineering toll

13. Viruses: Infectious particles, obligate intracellular parasites comprising genetic material (DNA or RNA) surrounded by a protein coat and/or an envelope derived from the host.

14. Characters of Viruses: Viruses are very small infectious agents (ranging from about 20 nm to about 300 nm in diameter ). Contain only one kind of nucleic acid (RNA or DNA) as their genome never both. The nucleic acid is encased in a protein shell (capsid), which may be surrounded by a lipid-containing membrane (enveloped) or not.

15. The entire infectious unit is termed a virion . Viruses are inert in the extracellular environment; they replicate only in living cells, being parasites at the genetic level Viruses are obligate intracellular parasites, lack cellular organelles and apparatus.

16. The viral nucleic acid contains information necessary for programming the infected host cell to synthesize virus-specific molecules required for the production of viral progeny. Viruses vary greatly in structure, genome organization and expression, in addition to replication & transmission strategies. The host range for viruses may be broad or extremely limited. Some viruses are known to infect unicellular organisms such as mycoplasmas, bacteria & algae. Also all higher plants & animals

17. Benefits of Viruses Phage typing of bacteria. Sources of enzymes. Pesticides. Anti-bacterial agents. Anti cancer agent! Gene vector from protein production. Gene vector for treatment of genetic diseases.

18. Important Virology Terms Capsid : The protein shell, or coat that encloses the nucleic acid genome . Capsomeres :Morphologic units seen in the electron microscope on the surface of the virus particles (represent clusters of polypeptides). Defective virus :A virus particle that is functionally deficient in some aspect of replication .

19. Envelope :A lipid-containing membrane that surrounds some virus particles (capsid) (acquired during viral maturation by a budding process through host cell membrane) Peplomers : Virus-encoded glycoproteins

20. Nucleocapsid :The protein-nucleic acid complex (representing the packaged form of the viral genome). Structural units ( Protomer ): The basic protein building blocks of the coat which are collections of more than one non- identical protein subunit. Subunit : A single folded viral polypeptide chain Virion : The complete infectious viral particle (serves to transfer the viral nucleic acid from one cell to another)