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Viruses & Bacteria Chapter 19.

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1 Viruses & Bacteria Chapter 19

2 Studying Viruses & Prokaryotes
Virus is an infectious particle made only of a strand of DNA or RNA that is surrounded by a protein coat Bacteria one-celled microorganisms that can also cause infection Pathogen any living organism or particle that can cause an infectious disease

3 Characteristics of all living things
Ability to reproduce Use nutrients and energy Grow and develop Respond to their environment Have genetic material

4 Soo what are viruses? Viruses can respond to their environment
They can obtain energy BUT THEY CANNOT REPRODUCE ON THEIR OWN Viruses are parasites that need a host in order to live, grow, and reproduce Viruses are much smaller than cells Viruses are not given a place in Linnaean classification

5 Virus INFO Viroid infectious particles that cause disease in PLANTS
They are made of single-stranded RNA without a protein coat They are passed through seeds or pollen Can cause havoc to agriculture by stunting the growth of plants

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8 Virus INFO Prion an infectious particle made only of proteins that can cause other proteins to fold incorrectly They are very unusual because they have no genetic material Diseases caused by prions Mad cow disease Bovine spongiform encephalopathy Creutzfeld-Jakob disease

9 Videos https://www.youtube.com/watch?v=aP-ShyyHiIc

10 Viruses Dmitri Ivanovsky made the discovery of the virus
He studied tobacco mosaic disease name for the scar tissue it leaves on the leaves of tobacco plants He thought it was caused by a bacterium Ivanovksy passed extracts of diseased tobacco leaves through filter pores small enough to strain out bacteria and found that the extracts could still pass on the disease How could this be? New bacteria? Unknown organism?

11 Viruses In 1898 Martinus Beijerinck built upon Ivanovsky’s work
He proposed that tiny particles within the extracts caused the infection Name them virus (meaning poison in latin)

12 Structure of a Virus A single viral particle can be termed a virion
Each virion has a protein shell called a capsid Some are surrounded by a lipid envelope Spiky structures can protrude from the envelope to protect the virion Some viruses attach to a cell with the spikes

13 Reproduce Viruses can only reproduce after they have infected host cells They can move from one host cell to the next because they have no cell structure maintaining them or constricting their spread All it needs to reproduce is its genes

14 Structure of a Virus Viruses can have several shapes and sizes
Each type of virus can infect only certain hosts A virus identifies its host by fitting its surface proteins to receptor molecules on the surface of the host cell (fits like a lock and key) Some viruses can infect several species some can only infect single species

15 Structure of a Virus

16 Viruses that infect Bacteria
Bacteriophages viruses that infect bacteria E. coli is an example of a bacteriophage that infects our intestines and makes us very ill

17 Viruses that infect Eukaryotes
These viruses differ from bacteriophages because of their methods of entering the host cell Many enter by endocytosis Endocytosis is the process of forming vesicles around the virus and attaching to the plasma membrane Vesicle is formed by the envelope on the virus They then enter into the cytoplasm and target the nucleus

18 Infection Types Lytic Infection Lysogenic infection
The cell bursts releasing the new viral offspring into the host’s system Combines its DNA into the hosts DNA

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21 First Defenses Skin viruses can only pass through the skin by entering through a cut or scrape, or any other opening in the body Mouth, nose, genital areas, eyes, and ears Receptors on cells lock out the virus Proteins on the surface of the viral capsid trick the receptors into letting it in

22 Viral Infections Common cold:
200 different viruses can cause the common cold They can mutate and change before you give it to the next person Usually last a week and there is no medication to help fight the virus

23 Viral Infections Influenza: Can cause an epidemic
Flu virus Spreads very quickly Can cause an epidemic Epidemic a rapid outbreak of an injection that affects many people 20% of the US population get influenza each year

24 Influenza 3 types of Influenza’s can infect humans
Some viruses can mutate and cause the flu to pass between different species Vaccine substance that stimulates the body’s own immune respone against invasion by microbes

25 HIV Human Immunodeficiency virus
HIV is a retrovirus is a virus that contains RNA and uses an enzyme called reverse transcriptase to make a DNA copy This DNA can remain dormant for years as a provirus, causing no symptoms to its human host DNA usually spreads via the lytic cycle and this causes the virus to kill our white blood cells which ultimately causes AIDS Many medications and antiviral drugs developed to fight HIV

26 Vaccines Vaccines are made from the same pathogen that it is supposed to protect against Vaccines consist of weakened versions of the virus that will cause the body to produce a response When the body encounters the virus the body can naturally fight it off because of the vaccine

27 Prokaryotes Archaea and bacteria
These are the most wide spread and abundant organisms on earth Thought to be 1030 types of prokaryotes on earth Many still unknown One gram of soil may contain up to 5 billion bacterial cells with 10,000 different types of bacteria

28 Prokaryotes Obligate Anaerobes prokaryotes that cannot live in the presence of oxygen Obligate Aerobes prokaryotes that need oxygen in their environment Facultative Aerobes can survive in the presence or absence of oxygen

29 Prokaryotic Domains All prokaryotes are single celled, have cell walls and plasma membrane, no organelles, circular DNA in the cytoplasm, many move using flagella Plasmid a small piece of genetic material that can replicate separately from the main chromosome Flagellum whip like structure outside of a cell that is used for movement

30 Prokaryotic Cell

31 Bacteria shapes Archaea shapes can vary immensely
Bacteria tend to have 3 shapes Rod shaped bacilli Spiral shaped spiralla Spherical shaped cocci

32 Bacteria Shape

33 Prokaryotes Archaea Bacteria Live in harsh conditions
Cell wall is not made of peptidoglycan Rarely causes disease in humans Cell wall differences cause medicine to be ineffective Cell walls made of peptidoglycan Lives in moderate conditions Medication kills bacteria cells

34 Gene Exchange Prokaryotes reproduce via binary fission (2 exact copies made with full amount of DNA) Prokaryotes can exchange genetic material to increase genetic diversity Conjugation exchange parts of their chromosomes through a hollow bridge of pili formed to connect two or more cells Prokaryotes can survive unfavorable harsh conditions with the help of endospores Endospores cell with a thick protective wall

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36 Endospore Endospores form by coping their chromosomes and produce a wall around the copy The thick wall can protect DNA from drying out, temp. changes, and disinfectants Can last for centuries

37 Endospore

38 Nutrients Prokaryotes provide nutrients to humans and animals
In humans we have bacteria in our intestines that assist us digest food. This is a mutualism relationship Many foods we enjoy are fermented by bacteria Yogurt Cheese Vinegar Pickles Soy sauce

39 Prokaryotes in Ecosystems
Prokaryotic cells in our ecosystem can help break down carbon, nitrogen, and hydrogen Cyanobacteria release oxygen into the atmosphere Legumes are nitrogen-fixing bacteria that are free-living Soybeans, beans, alfalfa, clover This is the purpose of crop rotation

40 Ecosystem Continued Some prokaryotes help break down pollutants Bioremediation Used to clean up oil spills (BP oil spill they fertilized beach to grow bacteria) Bacteria can break down basically any human waste which is very useful One important product they cannot break up is plastic (DO NOT LITER)

41 Bacteria causing diseases
Some bacteria can cause disease in plants and animals by disrupting the host organism’s homeostasis Can cause disease in 2 basic ways: Invade tissue and attack cells Make poisons Toxin a poison that is released by an organism

42 Tuberculosis Caused by the bacteria Mycobacterium tuberculosis
Multiply in the lungs killing the white blood cells that respond to invasion They body reacts by swelling and this can damage the lungs

43 Read pg. 575-575 Staph infections
Discuss what they are and how they are spread

44 Antibiotics Antibiotics kill off harmful bacteria that make someone sick Prime example Streptococcus or the common term “strep throat” Strep throat is a bacteria that can be killed with a antibiotic Medicine can be made naturally by bacteria or fungi It is important not to over medicate because this can kill good bacteria that helps fight diseases and other purposes

45 Resistance Drug resistance is the product of natural selection, as individuals who are more resistant are more likely to survive and reproduce Some bacteria are killed by the same antibiotic This allows for bacteria to become resistant by forming plasmids Plasmid small portion of DNA that holds certain genes (resistance)

46 Reasons for resistance
Overuse If you use a antibiotic when you are not sick with a bacteria it kills good cells and makes other resistant Underuse If you do not use the medication for its prescribed length of time it allows bacteria cells to adjust and become resistance Misuse We eat livestock that are medicated heavily to grow faster, and this can cause our bacteria cells to become resistant

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