Answer the following questions: Do bacteria have a nucleus?? Do bacteria have different shapes? Do bacteria have a cell membrane? A cell wall? How fast and how do bacteria divide? Are bacteria prokaryotes or eukaryotes? Are ALL bacteria bad?? WHAT are viruses- are they cells? Are they alive? What are they made of?

The Good, Bad, and Ugly

The GOOD and the BAD! Bacteria are both GOOD for us and our environment and BAD for our health. Can anyone name a GOOD purpose for bacteria? Can anyone name a Disease caused by bacteria?

Microbiology The study of single cell organisms too small to see with the unaided eye. Includes BACTERIA, Archaea, Fungi, Protists, and VIRUSES.

Domain: Bacteria Characteristics of bacteria: No membrane bound nucleus Have cell membrane, but NOT membrane bound organelles (like mitochondria) Most are unicellular & very small Ribosomes are different from ones in our cells Most Bacteria have a cell wall!

How Big are Bacteria? A BACTERIUM is the size of a PITCHER’S MOUND, And, ONE CELL from your BODY is the size of the BALLPARK!!!

BACTERIA Free living organisms. Multiple shapes: rod, sphere, or spiral

BACTERIA, cont. They can be found at extreme temperatures (boiling to freezing). They “eat” everything from sugar to chemicals. Classified as PROKARYOTES because they do NOT have a nucleus. DNA is the genetic material

What is a gram stain? Way to see almost transparent, very small bacterial cells under the microscope Used in laboratories as a first screening mechanism to characterize bacterial infections in people. Technique that differentiate bacteria into 1 of 2 groups: gram positive and gram negative.

How does it work? The purple or red stain correlates with differences in the structure of the bacterial cell wall Gram-positive- cell wall traps the dye; stain purple Gram-negative- cell wall cannot trap the purple dye; counter-stained red

Photomicrograph of gram+ and gram- bacteria. A) E Photomicrograph of gram+ and gram- bacteria. A) E. coli (common gram- rod found in colon). B) Staphylococcus epidermidis (gram + cocci found on skin C) Bacillus cereus (gram + rod in soil).

How do bacteria reproduce? Primarily by Binary fission- Simple & FAST! The DNA is copied The cell & cell wall divide in the middle to form 2 identical ‘daughter’ cells. Under optimal conditions, bacteria divide every 20 to 30 minutes. Occasionally, bacteria have sex (called conjugation) to increase genetic diversity and improve survival Process involves exchange of DNA between cells using the pili on the surface

How do we treat (kill) bad bacteria? ANTIBIOTICS!! The first antibiotic was discovered by Alexander Fleming in 1928. He noticed a mold (penicillium) inhibited growth of bacteria he was studying. He isolated the chemical from the mold and named it Penicillin.

Problems with antibiotics: The main difficulties with antibiotics are: 1. Allergies 2. Killing off the “good” bacteria in our bodies

Q. If antibiotics are so effective at killing living bacterial cells, why don’t they hurt our cells? A. Bacteria do not have the same organization as our cells and Antibiotics are SPECIFIC for the bacteria they can kill- they are only effective at killing certain types of bacteria

“GOOD” Bacteria Bacteria turns MILK into YOGURT (Lactobacillus acidophilus) and CHEESE. Bacteria help us digest our FOOD and produce Vitamin K (Escherichia coli). Clean wastes from sewage water at water treatment plants (Pseudomonas putida).

Good Bacteria, cont. A natural pest killer in gardens and on crops (Bacillus thuringiensis). Clean up chemicals at hazardous waste dumps and landfills (Methanotrophs). Make medicines, like ANTIBIOTICS or using biotechnology, Human Insulin.

Diseases caused by Bacteria: Lyme Disease (Borellia) Necrotizing Fasciitis (“Flesh eating” bacteria; Streptococcus pyogenes) Strep Throat (Streptococcus) Food poisoning (Salmonella sp., Staphylococcus aureus) Meningitis (Neisseria)

What determines the “type” of bacteria? Microscopic observation: - Shape & Grouping (single, chain, etc) - gram stain - motility Natural Environment Sequence of genes (recent technology)

How do bacteria cause disease? Attach to host cells & cause damage as take nutrients Increase number and crowd out normal cells Produce toxins that damage or kill cells Get inside normal cells and disrupt function Attack and damage cells in a particular part of the body

How else do we prevent disease? Excellent Sanitation Practices! Wash hands frequently! Wash foods before eating Careful food storage and preparation Treatment of human excrement to kill infectious agents Clean water supplies for drinking Clean cuts & wounds immediately after getting them Sterile practices in hospitals

How do diseases spread (transmission to people) How transmitted: 1. Breathe in respiratory droplets 2. Using infected needles 3. Introduced into wounds How to prevent: 1. Cover mouth when cough/sneeze 2. Use new needles 3. Thoroughly clean wounds

Cont….. 4. Insect bites 5. Sharing glasses & utensils 6. Touching surface & eyes,nose or mouth 7. Unprotected sex 4. Wear long pants; use bug spray 5. Don’t share, and wash well 6. Wash hands frequently; don’t touch mucus membranes to introduce! 7. Use condom/ abstinence

8. Eating contaminated foods or water (fecal-oral transmission; contaminated by food handler, animal the meat came from, incorrect food storage, contaminated water) 8. Wash hands before preparing foods; correct waste treatment; water treatment; Don’t drink water (only bottled!), uncooked fruits (unless peelable) or salads in developing countries;

A few terms ……. Pathogen- Microorganism that causes disease Infection: Occurs when microbes enter the body and begin to multiply; this SOMETIMES leads to Disease: Occurs when cells in body damaged (as result of infection) and signs and symptoms of illness appear.

VIRUSES Tiny parasites composed of: Genetic material (DNA or RNA) Protein In Some, a Membranous Envelope

VIRUSES, cont. Straddle between living and not living. Inert when outside of cells. Thousands of different viruses in a variety of shapes.

How are viruses classified? Type of nucleic acid that stores the genetic information: Double-stranded (ds) DNA Single-stranded (ss) DNA dsRNA ssRNA Shape of Capsid Presence or absence of a lipid “envelope”

Viruses exist to reproduce! If contacts a cell it CAN infect, the virus takes over the cell and makes lots of copies of itself! Viruses infect every form of life (plants, animals, fungi, bacteria)

Viruses, cont. Viruses do not “live” UNLESS they are inside a eukaryotic cell (one of ours!). Then, they use that cell as their own factory to make millions of new viruses.

Q. How do we treat viruses? A. With an antiviral. 1. This is a drug that will stop a virus from reproducing in our cells. 2. There are VERY few antivirals. 3. Antivirals are more toxic to our normal cells. Why are there so few antivirals available to treat viral infections?

VIRAL DISEASES AIDS (Human Immunodeficiency Virus) Flu (Influenza virus) Chicken Pox (Varicella-Zoster Virus) “Kissing Disease” or Mononucleosis (EBV) Hepatitis (Hepatitis A, B, C, etc) Colds (rhinovirus, coronavirus) Measles (rhabdovirus)

HOW DO BACTERIA AND VIRUSES DIFFER? SIZE: Bacteria are much larger. STRUCTURE: Bacteria are much more complex. Bacteria have a thick cell wall, a chromosome, & ribosomes. A virus has a small amount of nucleic acid and a protein coat. Antibiotics kill bacteria. Antibiotics do NOT kill viruses. Only antivirals kill viruses & they do NOT kill bacteria.

HOW DO BACTERIA AND VIRUSES DIFFER, cont… Bacteria are free living (a REAL cell!); they contain ALL they need to grow and reproduce themselves. One cell divides into 2 ‘daughter’ cells. Viruses require a host cell to reproduce: they are moochers due to their limited genetic information. They invade a cell and hijack its machinery to turn it into a VIRUS FACTORY!

How do we protect ourselves from viral or bacterial infections? With VACCINES!!

Vaccines, cont… 1. What are they? Part of a bacteria OR virus (or a weakened version of the organism) that is injected into a person. To be most protective, a person is usually injected multiple times months apart. Vaccines must be given weeks or months BEFORE you are infected

Vaccines, cont… 2. How do they work? The vaccine does NOT give the person the disease. BUT the immune system of the person “SEES” the bacteria or virus as an invader and REACTS to it by preparing the weapons to fight it off.

That’s why you feel sick! When we get sick, it takes our immune system several days to a week to “see” a foreign invader (bacteria or virus) and mount a response against it. That’s why you feel sick! If you’ve been vaccinated, your body will immediately “see” the bacteria or virus as an invader and attack it. It has the weapons to immediately fight it off You may NEVER know you were infected.

How does the immune response react? One way the immune response reacts is to make specific ANTIBODIES against a virus or bacteria. Later, if you are infected with that microorganism, the antibodies in your body will bind to it and stop it from infecting you.

How are Antibiotics & Vaccines different? Antibiotics kill ONLY bacteria. Vaccines can result in protection against a specific bacteria OR virus.

Which works immediately and which does not? Antibiotics start to kill the bacteria immediately after you take them Vaccines require several weeks (and possibly several shots) before they protect against the disease

TO DO: What do antibiotics & vaccines have in common? Both fight infectious agents -antibiotics ONLY fight bacteria - vaccines can protect against bacteria OR viruses Antivirals= very few available; ONLY fight specific viruses

INFLUENZA VIRUS Why do we need to be vaccinated EVERY year against Influenza?

Build an Influenza Virus: Working at your table, you will build an influenza virus using the package of supplies. Do NOT throw any of the parts away- they will be reused!!! To build: Put the Neuraminidase protein (NA; brass fasteners) and Hemagglutinin protein (HA; pipe cleaners) into the envelope of the influenza (flu) virus virion. Compare your virus with those around you!

How do the virions look the same? How do the virions differ? Which do you think are examples of antigenic drift? Why did you pick them? Put the molecules in order by FLU season Are there examples of antigenic shift? Which do you think might be an example of a Swine or Avian influenza virus?

Why do people need a vaccine EVERY year for Flu? Many different strains of Flu! DIFFERENT types infect people each year. WHY?? Influenza is one of the MOST changeable viruses! It makes mistakes when it copies the RNA genome. These result in changes (mutations) in the HA & NA protein.

HOW does the vaccine prevent us from catching the flu? When get the vaccine or “catch” the flu, our immune system “sees” & makes antibodies to HA & NA (it’s on the outside of the virus!). -These antibodies bind to HA & NA to stop the virus from infecting our cells. THAT’s how it protects us from getting sick!

What happens when HA & NA change? Antibodies to the previous HA & NA will not bind well (if at all) to stop the virus from infecting our cells As a result, we need a DIFFERENT vaccine every year to provide protection against the current strains.

What do we call it when the HA & NA change from year to year? ANTIGENIC DRIFT: Small changes in HA or NA over time. Parts of the HA or NA are similar, but enough of it is different that antibodies to “old” version no longer protect from infection

What happens when HA & NA are VERY different?- ANTIGENIC SHIFT Abrupt, major change in influenza virus HA and NA People have little or no immunity to the “new” virus- their immune response has never “seen” it so they get very sick! Happens infrequently; Example: animal influenza virus (like SWINE FLU or AVIAN Flu) infects PEOPLE!

Challenger Questions: Name 2 differences between Bacteria and our cells Name 1 difference between Bacteria and Viruses. Do antibiotics work when you have a cold (VIRUS infection)? Name a disease caused by a bacteria.

Name a disease caused by a virus. Name 2 good purposes for Bacteria. What is one way the body fights off bacteria and viruses? How can we PREVENT infection with bacteria OR viruses?