Bacteria Viruses Ch 19 Ch 23 and more

Bacteria & Viruses Ch 19, Ch 23, and more

Bacteria & Virus Overview • Interesting stuff! • We live with bacteria and viruses constantly, but most people don’t know much about them. • In this chapter we learn both the good and bad of each

Today’s Learning Objectives 1) Know the terms in this chapter. 2) Remember the 2 kingdoms of prokaryotes. 3) Know the 3 shapes of bacteria. 4) What are the 4 ways bacteria obtain energy? 5) How do bacteria respond to O 2? 6) What is the importance of bacteria?

Bacteria (19 -1) • Describe bacteria: • • Small (1 – 5 micrometers) Prokaryotes (organisms w/no nucleus) Single-celled May cause disease / may be healthful Oldest form of life (3. 5 billion years) Live everywhere Most are not harmful

Research • Louis Pasteur: studied fermentation of yeast to produce alcohol • Went on to invent the process of pasteurization to prevent the spread of small pox • Joseph Lister: introduced the use of disinfectant to clean surgical dressings in order to control infections (1860 s)

Bacteria • Classification (2 kingdoms) 1. Eubacteria – – – Large kingdom, much diversity Live almost everywhere Cell wall contains peptidoglycan Example: Escherichia coli (AKA E. coli) Lack organelles

E. coli, a Typical Eubacterium Ribosomes http: //www. cellsalive. com/animabug. htm Flagellum DNA Pili

Bacteria 2. Archaebacteria – Smaller kingdom? – Cell walls lack peptidoglycan • Examples: – Methanogens live in intestines & mud – Halophiles live in very salty waters where nothing else can live – Others live in near-boiling water

Bacteria • Characteristics used to identify types 1. Shape 2. Structures in cell walls 3. How they move 4. How they obtain energy

Bacteria • 3 shapes of bacteria 1. Bacilli – rod shaped 2. Cocci – spherical 3. Spirilla – spiral shapes

• Structures in cell walls – Gram-positive bacteria – have thick peptidoglycan walls, look purple under gram staining; antibiotics are effective – Gram-negative bacteria – have thin peptidoglycan walls with an outer fatty layer; look pink under gram staining; usually a second cell wall; antibiotics not very effective

Bacteria • How bacteria move – Some do not move – Some swim using flagella – Some slide on a layer of slime they secrete – https: //www. youtube. com/watch? v=q. C 5 Jv. OUq. Mjw – https: //www. youtube. com/watch? v=89 1 M 1 TH 99_8 – https: //www. youtube. com/watch? v=R 6 ab. ZKZ 9 EGM

Bacteria • How they obtain energy (4 ways) 1. Chemoheterotrophs 2. Photoheterotrophs 3. Photoautotrophs 4. Chemoautotrophs

Bacteria • Chemoheterotrophs – – Eat (absorb) chemicals as food – Sounds weird, but humans fit this category • Photoheterotrophs – – Need light for photosynthesis AND need to eat chemicals – Combine them to form more complex organic molecules

Bacteria • Photoautotrophs – – Use light to convert chemicals to energy – Photosynthesis – Ex. cyanobacteria • Chemoautotrophs – – Use chemicals to convert other chemicals into energy – Like photosynthesis, but without light – Ex. bacteria at deep ocean thermal vents

Bacteria • Bacteria also differ importantly in how they respond to oxygen – Obligate aerobes – require oxygen to live • Ex. Mycobacterium tuberculosis – Obligate anaerobes – die if oxygen is present • Ex. Clostridium botulinum – Facultative anaerobes – can live with or without oxygen being present • Ex. E. coli

Bacteria • Bacterial reproduction – Always asexual, can be as often as every 20 min. – Binary fission – bacteria grows to nearly twice its normal size, duplicates DNA, then divides in half

Bacteria • Other genetic processes – Conjugation – can exchange DNA with other bacteria through a conjugation bridge – Spore formation – in unfavorable environments, the bacteria forms a smaller structure with just its DNA and a little cytoplasm • It then goes dormant until survival conditions improve

Bacteria Importance of bacteria in environment – Some photosynthesize and are basis of food chain – Others are decomposers that recycle nutrients from dead organisms – Important role in nitrogen cycle • Bacteria are the only organisms that can change nitrogen from atmosphere into forms other organisms can use • Called “nitrogen fixation” because it “fixes” the nitrogen so plants and animals can use it • Nitrogen required for life! Component of proteins and DNA.

Nitrogen Cycle

Bacteria • Human uses for bacteria – Need them in and on our bodies (protection, vitamin production, etc. ) – Used in food production ( yogurt, cheese) – Used to produce drugs (insulin, penicillan) – Other manufacturing processes (toothpaste, ice cream)

Today’s Learning Objectives 1. What are the parts of a virus? 2. How do viruses get into a cell? 3. How are the lytic cycle and lysogenic cycle different? 4. Form an opinion on whether viruses are living or nonliving, and support that opinion with facts.

Viruses (19 -2) • Virus – a particle of nucleic acid, protein, and sometimes lipids – Viruses enter cells of other living things, hijack their nuclei and other organelles, and produce copies of themselves – Basically act like parasites – Very tiny, much smaller than bacteria – pathogenic

Viruses • Virus structure – Core of DNA or RNA surrounded by a protein coat • capsid – the protein coat of a virus – May also have fatty layer too – Shape varies: • Complex and geometric • Simple and irregular

Viruses • Bacteriophage – virus that infects bacteria, commonly studied example of a virus

Viruses • How viruses get into a cell – The capsid and the cell of the host have to match • Proteins on the capsid must match receptors on the cell, or vice versa – When the proteins & receptors randomly come in contact, the virus injects its DNA or RNA into the cell – Once inside the cell, it has options… – Not considered alive because…. .

Viruses • Two different types of viral infections 1) Lytic infection 2) Lysogenic infection

Viruses • Lytic infection – in this type of infection, the virus immediately takes over the host’s cell and uses its organelles to make copies of itself – When enough copies are made, it splits (or “lyses”) the cell, killing it, and releasing the new viruses – 100 viruses in 20 minutes – Animation

Viruses • Lysogenic infection – In this case the virus merges its DNA with the host’s DNA, and could stay there for months or years before causing problems – After some period of time, the viral DNA is activated by something – It then begins a lytic infection – Animation

Viruses • Retroviruses – viruses with RNA instead of DNA – Important because they have unusual ability to make DNA from RNA (reverse transcription) – HIV is an example of this type of virus

Are viruses alive? • Yes because: – They reproduce (only within a host) – They use energy (only within a host) – They have genes – They evolve • No because: – They are not made of cells – They cannot live or reproduce without the host – They do not grow, obtain energy, or respond to the environment

Today’s Learning Objectives 1. Know the two methods bacteria use to cause disease. 2. Describe three methods humans use to fight bacterial disease. 3. List 4 diseases caused by viruses. 4. We’ll go into detail about 5 viral diseases. Pick one and describe 3 details about it. 5. What are prions and viroids?

Viral & Bacterial Disease (19 -3) • Only a few bacteria and viruses cause disease – Most bacteria are harmless • Pathogens – disease-causing agents • Enter us: water, air, touch, food, insects

Viral & Bacterial Disease • Examples of diseases caused by bacteria – Tuberculosis – Strep throat – Lyme disease – Tetanus – Bacterial meningitis – Anthrax – Pneumonia (some types) – Chlamydia – Botulism – Salmonella

Viral & Bacterial Disease • Two methods bacteria cause disease: – Some damage cells directly and injure the organism • Ex. bacteria that causes tuberculosis – Some produce toxins that make the organism sick • Ex. the bacteria that causes strep throat and scarlet fever • Botulism https: //www. youtube. com/watch? v=A_QTg. Kw. HEw

Viral & Bacterial Disease • Three methods of fighting bacterial diseases 1. Body’s immune system will fight infections 2. Vaccine – a solution of weakened or killed pathogens that prepares the body’s immune system to fight off disease 3. Antibiotics – chemicals that block the growth or reproduction of bacterial invaders

Viral & Bacterial Disease • Methods of preventing bacterial exposure – Sterilization – using high temperatures to kill bacteria and bacterial spores – Disinfectant – using a chemical that kills pathogenic bacteria – Food processing – using heat, refrigeration, or pressure to prevent bacteria from growing in food

Viral & Bacterial Disease • Viral diseases – Viruses can only enter a specific type of cell – The symptoms of the disease depend on which type of cell it enters and destroys • Ex. if it kills nerve cells, could cause paralysis (Poliovirus) • Ex. if it attacks white blood cells, it could prevent immunity (HIV) • Ex. if it disrupts the DNA of a normal cell in a specific way, it could make it cancerous

Viral & Bacterial Disease • Viruses cause a wide range of human disease: – – – – – The common cold, Influenza, Chickenpox, Smallpox, Rabies, AIDS, Cervical Cancer, Ebola, West Nile, Herpes And many more • Also animal diseases: – Foot and mouth disease (cattle) • Also plant diseases: – Tobacco mosaic virus

Defense Against Viruses • Antibiotics do not work • Interferon can work ( body natural defense) • Drugs that block cell enzymes for DNA replication like AZT (slows diseases, very toxic) • Vaccines • Salk: developed first polio vaccine • Small pox: killed ½ the people who contracted it

Influenza #1 of 5… • Influenza = the flu – mild to severe illness, can be lethal • Every year in the United States, on average: – 5% to 20% of the population gets the flu; – more than 200, 000 people are hospitalized from flu complications, and; – about 36, 000 people die from flu. – Worst Flu in 20 th Century https: //www. youtube. com/watch? v=8 N RTC 1 Bl. Hg 0

Bird Flu #2 of 5 • • • In the news… Bird Flu or Avian Flu Currently only infectious among birds, but about 584 people have caught it anyway, 385 of those have died (what % fatal? ) Scientists worried virus will mutate and become infectious among people (like H 1 N 1 did)

Smallpox Eradication #3 of 5 • 1967 WHO (World Health Organization) started campaign to wipe out smallpox • Smallpox killed 50% of people who got it, and left rest badly scarred, some blind • WHO vaccinated people in poorest countries • One by one, countries reported no more infections • Smallpox declared eradicated in 1980

HIV Treatment, #4 of 5 • HIV is virus that causes AIDS • Treatment, but no cure – “Cocktail” of antiviral drugs to fight off quickly adapting virus

Emerging viruses #5 of 5 • Emerging viruses – viruses that are relatively new to humans and are life threatening – Hantavirus – Southwestern US – HIV - Global – Ebola – Central Africa (massive, 90%) – SARS – Global – Avian flu – Asia, Europe, Africa – Swine flu (H 1 N 1) – ZIKA (not sure yet)

Not quite viruses… • Viroids – – RNA with no capsid, cause plant disease • Prions – – Misshapen proteins that cause disease – Cause diseases like: • Scrapie (in sheep) • Chronic Wasting Disease (deer) • Bovine Spongioform encephalopathy (BSE) AKA: Mad Cow Disease • Creutzfeld Jakob Disease (CJD)