Microbe Mission

Description
Teams will answer questions, solve problems, and analyze data pertaining to microbes and microscopes.

The Stations
If there are stations, there will be 8-20 of them. They will be marked with roman numerals (I, II, III...) or they will be numbered (1, 2, 3...). There will be sections in the test corresponding to each of the stations with questions (the format of which is decided by the tester, and can vary widely from tester to tester). Students typically have a time limit at stations (i.e. 5 minutes per station, then rotate).

The Test
The test will pages/sections corresponding to the individual stations (if there aren't stations then it will be a normal test). It will have blank lines for you to record your answer. There will be no questions/diagrams in the packet, so all work must be done at the corresponding station. All answers must be recorded in the packet. Spelling does count in the packet. Points may also be taken away if the packet is not neat or legible. As you record your answers, make sure that you are recording on the right page/section/question. This may save you time and effort.

Please note that there may be lines for your team name, team number, or the participants' names on each page. No matter what, ALWAYS make sure you fill out that information on each page. If you don't, points can be taken off.

Materials
Each participant must bring Z87 chemical splash goggles and a writing implement and may bring a non-programmable, non-graphing calculator, and a 2 SIDED 8.5"x11"PAGE OF NOTES with any information in any form from any source. Students are allowed to put diagrams and other things on the note sheet. NO OTHER RESOURCES ARE ALLOWED. Students must REMEMBER all Diagrams and study material. Make sure you print the guide to this event in the event info on soinc.org.

Preparing for This Event
Make a binder! This will help you tremendously in preparing for this event. Even though you can't bring it in, it's a great way to keep all your information in the same place and to remember it.

With your notes page, include pictures and charts of things you need to remember. Also remember how your page is laid out and where you put everything. In a timed test, trying to find things on your notes page is a waste of time.

If you can acquire an AP Biology textbook, it will help tremendously with learning terms and concepts.

It is also very helpful to practice, because the type of questions can vary widely from test to test. Practice tests are extremely helpful in preparing for this event.

Covered Information
You will be tested on topics relating to microbiology, ranging from different types of microscopes and microbes to learning about cell structure and uses for microbes. You will also be tested on being able to read a dichotomous key and understanding the principles of microscopy.

Prions
Prions are infectious proteins that are responsible for a class of diseases known as the Transmissible Spongiform Encephalopathies, which are neurodegenerative diseases including Mad Cow Disease and kuru. Prions destroy the tissue of the nervous system, forming holes in the brain and nervous systems. Prion diseases all involve modification of the prion protein, a normal part of mammalian cells. They are also all fatal and rapidly progressive. Like viruses, prions cannot replicate on their own and rely on other organisms. Unlike other microbes, prions do not contain nucleic acids. Prions are thought to have originated from ZIP proteins.

Viruses
Viruses are microorganisms much smaller than bacteria that invade other cells in order to replicate. Viruses are responsible for a variety of diseases, such as chicken pox. The origin of viruses is unclear; some may have come from plasmids (pieces of DNA that can travel between cells) or transposons (pieces of DNA that can move themselves to different places in a cell's genome) while others may have evolved from bacteria.

Some viruses, known as bacteriophages, infect bacteria. Their appearance is often compared to that of an alien landing pod. Typically, their genome is composed of DNA rather than the RNA of retroviruses. Other viruses, most famously Sputnik, infect other viruses. These are known as virophages.

Viruses can be cause either lytic or lysogenic infections. In a lytic infection, the virus injects its genome into the host cell, which cannot differentiate between viral DNA and its own DNA. The cell begins to make mRNA from the viral DNA, which is then made into viral proteins that destroy the cell's DNA. When the cell eventually shuts down, the virus continues to use the cell to replicate. Enough viruses are made to cause the cell to burst, or lyse. Hundreds or thousands of released viruses then go on to infect other cells.

In a lysogenic infection, a virus integrates its DNA into the host cell's DNA. This viral DNA is known as a prophage. The propahge remains dormant in the cell's DNA for several generations before becoming active, leaving the cell's DNA, and directing the synthesis of new viral proteins. HPV, which causes AIDS, is a lysogenic virus.

Bacteria
Bacteria are single-celled, prokaryotic microorganisms. Some bacteria are beneficial to humans while others are pathogenic, but a majority of bacteria is harmless to humans. Pathogenic bacteria are responsible for a variety of diseases including strep throat and tetanus. Bacteria come in 3 shapes: coccus(circular), bacillus (rod-shaped), and spirillum (spirally). Bacteria originate from the single-celled organisms that were the first to inhabit the Earth.
 * Note: The bacterial shapes are only necessary to remember for division C, although it is always helpful to know them.

Archaea
Archaea are a group of single-celled microorganisms that were previously thought to be bacteria. Archaea inhabit some of the world's most extreme environments including the ocean floor. Archaea are prokaryotes. Their origin and potential for causing disease are currently unclear; however, archaea are thought to be ancestors of eukaryotes or very close descendants because of their many similarities, including genes and inclusion of enzymes in translation and transcription processes. Unlike bacteria, no known species of archaea form spores.

Fungi
Fungi are eukaryotic organisms that can be single-celled or multi-celled. Fungi have cell walls composed of chitin, unlike the cellulose walls of plants. Fungi are heterotrophic and do not have chloroplasts like photoautotrophs. Technically, fungi are more closely related to animals than they are to plants and likely shared a common ancestor with animals. Fungi are responsible for diseases such as athlete's foot.

Protists
Protists are eukaryotic but do not have specialized tissues. Algal protists are similar to plants and can go through photosynthesis, but do not have cuticles that prevent water loss. As a result algal protists must live in water. Animal like protists are called protozoa and are eukaryotic and heterotrophic. These protists consume other protists and bacteria for food. Some have two nuclei: the macronucleus and the micronucleus. Many move with cilia, flagella, or pseudopodia (in the case of amoebae). They also have complex life cycles. For example, they may exist in a trophozoite, or feeding, form. They can also change into a dormant form known as a cyst, which can help in reproduction.

Endosymbiotic Theory
Championed by Lynn Margulis in the 1960s, the endosymbiotic theory holds that mitochondria and chloroplasts in eukaryotic cells originated from proteobacteria and cyanobacteria, respectively. Evidence for this theory includes that mitochondria and chloroplasts divide through binary fission, not mitosis like the rest of the cell. These organelles, which are the same size as bacteria, also have their own different, circular DNA and two membranes. Chloroplasts in some algae have cell walls of peptidoglycan.

Gram Staining
Gram staining is a type of differential staining, meaning it separates bacteria into two different groups (Gram-positive and Gram-negative) based on their reactions to the procedure. Because of widely varying responses, Gram staining cannot be performed on archaea.

The first step in the procedure is to heat fix the bacteria; then, those bacteria are stained with crystal violet, the primary stain, for one minute. In an aqueous solution, crystal violet disassociates into CV and Cl ions, which penetrate through the cell wall. CV ions react with negatively charged particles in bacterial cells and stain them purple.

The third step is to apply iodine as a mordant, or trapping agent, for one minute. It reacts with the crystal violet and prevents removal of the purple stain. After the remaining iodine is rinsed away, alcohol decolorizer (sometimes acetone) is added until the primary stain is removed in Gram-negative bacteria because alcohol dissolves the outer membrane. In contrast, Gram-positive bacteria retain the primary stain because it becomes trapped in their thick, multi-layered walls of peptidoglycan.

The final step is to apply safranin (sometimes basic fuchsin) as a counterstain. This gives the Gram-negative bacteria their final red-pink color.

Characteristics of Gram-Positive Bacteria
Typically, Gram-positive bacteria produce exotoxins and are susceptible to phenol disinfectants. They retain the blue-purple color of crystal violet in Gram staining because of their thicker walls of peptidoglycan. Unlike Gram-negative bacteria, they lack the periplasmic space between the cytoplasmic and outer membranes because Gram-positive bacteria lack an outer membrane. Certain types of Gram-positive bacilli, most importantly Lactobacilli (used in milk and dairy products), cannot form spores.

Characteristics of Gram-Negative Bacteria
Gram-negative bacteria have thinner walls of peptidoglycan and two membranes and periplasmic space between them. Because of the safranin counterstain, they become red-pink after Gram staining. There are many Gram-negative aerobic (oxygen-using) bacteria.

Diseases for 2010-2011
In progress.

Viral Diseases
Viral diseases are immune to antibiotics; therefore, vaccines are typically the best form of prevention.


 * AIDS (caused by the HIV virus)
 * Chicken Pox and Shingles (caused by the varicella zoster virus)
 * Common cold (often caused by the rhinovirus but can also be caused by coronaviruses and adenoviruses)
 * Dengue fever (caused by the mosquito-borne dengue virus)
 * Ebola Haemorrhagic Fever (caused by the ebola virus)
 * Herpes (caused by the herpes simplex virus type 1 and type 2)
 * Influenza (caused by viruses of the family Orthomyxoviridae)
 * Measles (caused by the morbillivirus)
 * Mumps (caused by the mumps virus)
 * Mononucleosis, also known as mono or glandular fever (caused by the Epstein-Barr virus)
 * Polio (caused by the poliovirus)
 * Rabies (caused by the rabies virus)

Sample Exercises
1. Provide two differences between bacteria, viruses, and fungi.

2. Using the following key, determine (from pictures) which cell, A, B, or C is considered an alga.

3. Based on the following graph, determine which organism is best suited for growth in acid environments.

4. A cell is observed through a light microscope at 4x magnification. The cell takes up about half of the visual field. What is the approximate length of this organism?

5. Students observe a Petri plate with many different colonies on it. Based on the color of the colony, how many different kinds of organisms do you detect? Which type of organism appears to be the most prevalent?

6. From the following picture, identify the organelle, provide its function, and state which type of microbe it is unique to.

7. What type of microbe is involved in the production of most breads? What type of organism is responsible for polio?

8. Based on the following graph, what will be the microbial population/ml after 3.5 hours of growth?

9. Provide two distinctive properties of viruses, then provide the name of two diseases that are caused by viruses. As a variation on this type of question, match the disease with the type of microbe that causes it.

Useful links

 * Has information specific to cells
 * Has vocabulary
 * Bacteriology text
 * Microbiology text