Starting with MICROBIOLOGY

Transcription

1 Starting with MICROBIOLOGY Micro means very small and biology is the study of living things. Microbes are the oldest form of life on Earth. They've been here for 3.8 billion years! Microbes live everywhere. They live, in soil, rocks, air, animals, and even in our colons! Some microbes are harmful because they cause diseases, but other microbes are beneficial 1

2 Types of Microorganisms Viruses (do not belong to a Kingdom) Bacteria (Kingdoms Eubacteria and Archaeobacteria) Protists (Kingdom Protista) Fungi (Kingdom Fungi) 2

3 Viruses Latin for the for the word Poison A non-cellular particle made up of genetic material and protein that can invade living cells Genetic material= DNA or RNA Examples: influenza (common cold) HIV (human immunodeficiency virus) H1N1 (bird flu) HPV (human papilloma virus) = warts influenza HIV 3

4 Viruses tobacco mosaic virus Must infect living cells for reproduction and as such cannot be grown in culture in labs Have living and non-living characteristics: Living Has genetic material Non-living But only DNA or RNA, not both Can reproduce Can mutate Can be killed (sterilization) But needs a host cell to do it Non-cellular Do not grow, no metabolism 4

5 Typical Shape and Structure About 0.2 microns in size, or cm Shapes: rods, blocks, polyhedrons, and complex forms Core of genetic material (DNA or RNA) Surrounded by protein coat (CAPSID) Some have a lipid ENVELOPE surrounding this 5

6 Typical Shape and Structure 6

7 Example: BACTERIOPHAGE A virus that attacks bacteria! (A retrovirus has RNA instead of DNA) 7

8 Virus Reproduction Use INDIRECT reproduction (a host cell does all the work) Two types of life cycles a virus may use: LYTIC or LYSOGENIC LYTIC LIFE CYCLE (fast and destructive ) causes disease = virulent STEPS: 1. virus attaches to host cell 2. virus inserts its genetic material into host cell 3. viral genetic material remains separate from host cell DNA 4. host cell machinery manufactures viral parts 5. parts assemble inside the cell to form new viruses 6. viruses leaves host cell (explodes= LYSIS) and infect other cells 8

9 LYTIC LIFE CYCLE GIZMOS ACTIVITY: VIRUS LYTIC LIFE CYCLE 9

10 Virus Reproduction LYSOGENIC LIFE CYCLE (delayed = latent) STEPS: 1. virus attaches to host cell 2. virus inserts its genetic material into host cell 3. viral genetic material becomes part of host cell DNA 4. host cell reproduces, making more copies of viral genetic material as well as its own 5. a STRESS activates the dormant viral genetic material 6. host cell machinery manufactures viral parts 7. parts assemble inside the cell to form new viruses 8. viruses leaves host cell (explodes= LYSIS) and infect other cells e.g. Cold Sore Virus STRESS 10

11 LYSOGENIC LIFE CYCLE 11

12 Viruses that cause Human Disease 12

13 SPREAD of VIRAL INFECTION The mechanism of spread depends on the type of virus Some are airborne (via sneezing/coughing etc), others spread through bodily fluids (blood, semen, saliva) Some only require skin-to-skin contact ACTIVITY: Spread of Virus Simulation 13

14 VIRAL SPECIFICITY Viruses can only invade or infect certain organisms or cells = SPECIFICITY Most viruses are classified based on the type of host cell they infect E.g. Tobacco mosaic virus a virus that attacks tobacco plants and causes a mosaic pattern on the leaves (no smoking while harvesting tobacco!) For Humans, we often use more general names E.g. small pox, polio, chicken pox, measles, hepatitis, cold sores, HIV 14

15 VIRAL SPECIFICITY Some viruses are even more specific and will only attack specific tissue E.g. Polio viruses only invade nerve tissue E.g. hepatitis only occurs in the liver E.g. mumps attack salivary glands in the mouth Specificity is determined by the viral glycoprotein spikes (keys) being able to bind to the host cell receptors (locks). If they do not fit exactly, no infection will occur. Virus Host Cell 15

16 SYMPTOMS OF VIRAL INFECTION NEVER use ANTIBIOTICS to treat a VIRAL infection!!!!! 16