The Effects of Antibiotics on Bacterial Growth Bacteria are the most common and ancient microorganisms on earth. Most bacteria are microscopic, measuring 1 micron in length. However, colonies of bacteria grown in a laboratory petri dish can be seen with the unaided eye. There are many divisions and classifications of bacteria that assist in identifying them. The first two types of bacteria are archaebacteria and eubacteria. Both groups have common ancestors dating to more than 3 billion years ago.

Archaebacteria live in environments where, because of the high temperature, no other life can grow. These environments include hot springs and areas of volcanic activity. They contain lipids but lack certain chemicals in their cell wall. Eubacteria are all other bacteria. Most of them are phototrophic, i.e. they use the sun’s energy as food through the process of photosynthesis.

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Another classification of bacteria is according to their need of oxygen to live. Those who do require oxygen to live are considered aerobes. The bacteria who don’t use oxygen to live are known as anaerobes.

The shape of specific bacteria provides for the next step in the identification process. Spherical bacteria are called cocci; the bacteria that have a rodlike shape are known as bacilli; corkscrew shaped bacteria are spirilla; and filamentous is the term for bacteria with a threadlike appearance. Hans Christian Joachim Gram, a Danish microbiologist, developed a method for distinguishing bacteria by their different reaction to a stain. The process of applying Gram’s stain is as follows: the bacteria are stained with a violet dye and treated with Gram’s solution (1 part iodine, 2 parts potassium iodide, and 300 parts water). Ethyl alcohol is then applied to the medium; the bacteria will either preserve the blue color of the original dye or they will obtain a red hue. The blue colored bacteria are gram-positive; the red bacteria are identified as gram-negative. Bacteria contain DNA (deoxyribonucleic acid) just like all cells.

However, in bacteria the DNA is arranged in a circular fashion rather than in strands. Bacteria also contain ribosomes which, like in eukaryotic cells, provide for protein synthesis. In order for a bacterium to attach itself to a surface, it requires the aid of pili, or hairlike growths. Bacteria, just like sperm cells, have flagella which assist in movement. But, sperm cells only have one flagellum, whereas bacteria contain flagella at several locations throughout their body surface. Although most bacteria are not harmful, a small fraction of them are responsible for many diseases.

These bacterial pathogens have affected humans throughout history. The “plague”, an infamous disease caused by bacteria, has killed millions of people. Also, such a disease as tuberculosis, a disease responsible for the lives of many, is caused by bacterial pathogens ingested into the body. Bacteria affect everyone in their daily life because they are found nearly everywhere. They are found in the air, in food, in living things, in non-living things, and on every imaginable surface. Escherichia coli is a disease causing gram-negative bacillus.

These bacteria are commonly found within the intestines of humans as well as other vertebrates. This widely spread bacteria is known to cause urinary tract infections as well as diarrhea. Microcococcus Luteus are gram-positive parasitic spherical bacteria which usually grows in grapelike clusters. This species is commonly found in milk and dairy products as well as on dust particles.

Bacillus Cereus are a spore forming type of bacteria. They are gram-positive and contain rods. Due to the fact that this bacteria is known to survive cooking, it is a common cause of food poisoning and diarrhea.

Seratia Marscens a usually anaerobic bacteria which contains gram-negative rods. This bacteria feeds on decaying plant and animal material. S. marscens are found in water, soil, milk, foods, and certain insects. In spite of the fact that bacteria are harmful to the body, certain measures can be taken in order to inhibit their growth and reproduction. The most common form of bacteria fighting medicines are antibiotics.

Antibiotics carry out the action which their Greek origin suggests: anti meaning against, and bios meaning life. In the early parts of the 20th century, a German chemist, Paul Ehrlich began experimentation using organic compounds to combat harmful organisms without causing damage to the host. The results of his experimentation began the study and use of antibiotics to fight bacteria. Antibiotics are classified in various ways. They can be arranged according to the specific action it has on the cell.

For example, certain antibiotics attack the cell wall, others concentrate on the cell membrane, but most obstruct protein synthesis. Another form of indexing antibiotics is by their actual chemical structure. Practically all antibiotics deal with the obstruction of synthesis of the cell wall, proteins, or nucleic acids. Some antibacterials interfere with the messenger RNA, consequently mixing up the bacterial genetic code. Penicillins act by inhibiting the formation of a cell wall. This antibiotic works most effectively against gram-positive streptococci, staphylococci (e.g. Micrococcus Luteus) as well as certain gram-negative bacteria.

Penicillin is usually prescribed to treat syphilis, gonorrhea, meningitis, and anthrax. Tetracycline inhibits protein synthesis in pathogenic organism. This antibiotic is obtained from the culture of Streptomyces. Streptomycin an antibiotic agent which is obtained from Streptomyces griseus. This antibiotic acts by limiting normal protein synthesis. Streptomycin is effective against E.

Coli, gram-negative bacilli, as well as many cocci. Neomycin an antibiotic derived from a strain of Streptomyces fradiae. Neomycin effectively destroys a wide range of bacteria. Kanamycin an antibiotic substance derived from Streptomyces kanamycetius. Its antibacterial action is very similar to that of neomycin. Kanamycin works against many aerobic gram-positive and gram-negative bacteria, especially E.

coli. Protracted use may result in auditory as well as other damages. Erythromycin is an antibiotic produced by a strain of Streptomyces erythreaus.

This antibiotic works by inhibiting protein synthesis but not nucleic synthesis. Erythromycin has inhibitory effects on gram-negative cocci as well as some gram-positive bacteria. Chloramphenicol is a clinically useful antibiotic in combating serious infections caused by certain bacteria in place of potentially hazardous means of solving the problem.

In lab tests, it has been shown that this medicine stopped bacterial reproduction in a wide range of both gram-positive and gram-negative bacteria. The inhibition of cell reproduction caused by Chloramphenicol takes place through interference with protein synthesis. An experiment was conducted in order to determine which antibiotics are most effective in inhibiting bacterial growth. First, the different bacteria were placed on agar inside petri dishes. Then, antibiotic discs were placed into the dishes. Each bacteria was exposed to every one of the antibiotics listed above. The bacteria used in the experiment were: Bacillus Cerus, Escerichia Coli, Seratia Marscens, and Micrococcus Luteus. After a 24 hour incubation period, the results were measured.

In order to determine which antibiotic had the most effect their zones of inhibition were recorded. The zone of inhibition refers to the distance from the disc to the outermost section around the disc where no bacterial growth was present. The results can be seen on the graph and data chart.The following is a table showing the different zones of inhibition of each antibiotic in the bacteria culture: TetracyclineChloramphenicolKanamycinNeomycinPenicillinStreptomycinErythromycinB. Cerus5.

5956.61713E. Coli74.25.54.5no effect4.6no effectS.

Marscensno effectno effect4.54no effect3no effectM. Luteus2322101123.

511.519 After analysis of the data obtained it is obvious that each antibiotic had a distinct effect on the growth of the different bacteria. The results of this experiment are very important, since they teach of how each bacteria reacts to different antibiotics. This is very valuable because it is the information which assists physicians in prescribing certain medications to cure diseases caused by bacteria.Bibliography:Bibliography1) Encart Encyclopedia 1994, CD-ROM.

2) McGraw-Hill Encyclopedia of Science and Technology, 1992.3) Physicians’ Desk Reference, 1996.


A boy comes of age in an Italian-American neighborhood in the Bronx. His father gives him a piece of advice: “Nothing is more tragic than a wasted talent.” A street-corner gangster gives him another piece of advice: “Nobody really cares.” These pieces of advice seem contradictory, but the boy finds that they make a nice fit.

The kid, whose name is Calogero but who is called C, idolizes Sonny. He likes the way Sonny exercises a quiet authority, and talks with his hands, and dresses well. When C is 17, he goes to work for Sonny, against his father’s wishes. And in the year when most of the film is set, he learns lessons that he will use all of his life. “A Bronx Tale” was written for the stage by Palminteri, who plays Sonny with a calm grace in the film, but was Calogero in real life. There have been a lot of movies about neighborhood Mafiosos (Martin Scorsese’s “Goodfellas” was the best), but this movie isn’t like the others. It doesn’t tell some dumb story about how the bus driver and the mobster have to shoot each other, or about how C is the hostage in a tug of war.

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It’s about two men with some experience of life, who love this kid and want to help him out. Lorenzo, the bus driver, gives sound advice: “You want to see a real hero? Look at a guy who gets up in the morning and goes off to work and supports his family. That’s heroism.” But Sonny gives sound advice, too. One of the things he tells C is that you cannot live your life on the basis of what other people think you should do, because when the chips are down, nobody really cares. You’re giving them a power they don’t really have. That sounds like deep thinking for a guy who hangs on the corner and runs a numbers racket, but Sonny, as played by Palminteri, is a complex, lonely character, who might have been a priest or a philosopher had not life called him to the vocation of neighborhood boss. Nine year-old Calogero (Francis Capra) is the streetwise son of Lorenzo Anello (Robert De Niro), a bus driver who takes pride in his work ethic and expects to instill the same values in his son.

Calagero, however, is in awe of the local mob boss, Sonny (Chazz Palminteri), and when Calogero keeps his mouth shut after witnessing Sonny do a hit, the boy is taken under Sonny’s wing and shown the ways of the wiseguys. Lorenzo cannot keep his son away from the influence of Sonny, much as he tries, and a battle of wills ensues, pulling Calogero in both directions until he decides to settle the matter himself by seeing Sonny on the sly and behaving the best he can with his family. As he reaches his teen years, Calogero (now played by Lillo Brancato who looks so much like De Niro it’s downright spooky) finds that Sonny has become a true friend and that his education is twofold – both from school and from the streets. A young Italian American named Calogero (played by Lillo Brancato and Francis Capra), grows up in the Bronx, torn between the quiet honor of his father (Robert De Niro), and the authoritative aura of a neighborhood Mafia boss, Sonny (Chazz Palminteri). Both men care about the boy, but, against his father’s wishes, Calogero (nicknamed “C”) goes to work for Sonny. Calogero ends up participating in activities he wants no part of, but cannot refuse due to peer pressure.

He falls for a black girl named Jane (Taral Hicks), during a period when racism against blacks is intense and violent, but he must find his own way in life.


Until recently, scientists believed that the sole source ofenergy responsible for life on earth was the sun.

In 1977, agroup of scientists researching the theory of plate tectonics,traveled to the floor of the equatorial Pacific Ocean anddiscovered something that could possibly explain how lifebegan on this planet. From the Galapagos Rift’s thermalsprings, scientists discovered densely populated communities ofseveral species never before observed. Since that time theFederal Government has devoted more than 10 million dollarsto research these communities and their evolutionary history. This figure, to many scientist’s dismay, is dramatically lessthan that of the space exploration program’s budget. Forexample, in 1992, the government budget for oceanographyresearch was $600 million while NASA spent 8.5 billion. We knowmore about the space around us than we do about our ownhome.

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Only 1 percent of the sea floor has been mapped. The seais the largest, most inaccessible, and least understoodecosystem on this planet.Since studies of these communities began, previous notionsthat cold darkness, and extreme pressure are inimical to lifehave been disproved. We now know that an ecosystem can besustained by unusual energy sources. The animals that havebeen discovered in hydrothermal vents are fascinating as wellas extremely important. The structure of these creatures issuch that a new kingdom has been discovered/created.

Previously scientists divided the living world into twokingdoms: bacteria, also known as prokaryote andeukaryotes (plants and animals). The difference between thetwo kingdoms was their genetics. The DNA of these newlydiscovered animals was distinct from the two other kingdoms.

They have been called archaea. Research on these animals islimited since they do not grow and culture well in alaboratory. These animals live in extremely hot temperaturesof 160 degrees Fahrenheit and higher, while microbes have beenfound living in boiling water. This revelation surely mustchange all of the “rules” we have for health standards. Thesenewly discovered facts must dramatically change the way wethink of life on earth.Living in these vents are entire communities ofinvertebrates: tube worms, mussels, clams, and even shrimp. Inthe absence of light and without the photosynthesizingplankton that provide most sea life with food, these animalshave an alternate way to live. These invertebrates haveformed symbiotic relationships with the bacteria living withthem.

The mechanics of this relationship are incrediblyinteresting. Bacteria thrive on sulfide which is found in ventwater (hydrogen sulfide). They use the sulfide’s chemical energyto produce organic carbon compounds similar to how plantsuse solar energy in photosynthesis.

The bacteria employchemical rather than light energy to transform inorganiccarbon to organic compounds. This process is calledchemosynthesis, and was at first thought to be a rarephenomenon. The invertebrate houses the bacteria andprovides chemicals needed for the process of chemosynthesis.

The bacteria in turn gives organic carbon compounds to theinvertebrate, which keeps the invertebrate alive, (so it expendslittle or no energy gathering its own food). An example of thistype of tubeworm can be found in vents along submarinemountain ranges off of the western coasts of Mexico andSouth America. One in particular, at a site called the RoseGarden in the Galapagos Rift is long and white with a luminousred plume. Upon examination it was discovered that theseworms have no mouth, stomach, or digestive system.

Theysurvive by extending their plume into the vent fluids absorbingnumerous compounds including sulfide which are turned overto the bacteria.The bacteria then provide food to their host. The existence of this symbiotic relationship between aninvertebrate and a bacteria is as incredible as their existence. Another feature of this relationship is their mutual dependenceon oxygen. Oxygen is an element required by the vent bacteriato perform its essential role.

Interestingly, this is one of thefew ways these communities are tied to the world away fromthe vent. The implications of this awesome discovery are providingus with leads, clues, and suggestions to where life began andwhere it is going. From biotechnology that can be used intracing fingerprints in a crime scene, to discovering where lifebegun, this great new breakthrough will immensely enhanceour understanding and comprehension of our life and ourenvironment. We do not yet know where this new informationwill lead us, as our knowledge as well as our funding andperhaps even our imagination is limited. We once thought theearth was flat, ancient man thought that lightning was froman angry g-d, and until recently scientists thought that lifewithout sunlight at the bottom of the ocean was impossible, sowe are left with an incredibly complex universe to study,starting with our planet.REFERENCES”Clues to Fiery Origin of LIfe Sought in Hothouse MIcrobes” by William J. BroadThe New York TimesMay 09, 1995 V144,pB7(N), pC1(L), col 5, (48 col in.

).”Depths of Ignorance” by Cindy Lee Van Dover. Discover September 1993 V14, n9, p. 37(3).”Hydrothermal-Vent Communities of the Deep Sea” byVerena Tunnicliffe American Scientist July/August 1992V80, n4, p.336(14).Words/ Pages : 887 / 24


Life You Save May Be Yours By O`Conner In rural America there are many lame people that are of no use to this society. The reason these people live in such slums is simply because they are worthless, just like the bums on the streets of the big cities, these people have no ambition. They sit around all day and rock back and back and forth in their rocking chairs made by the only person in their gene pool that has any common knowledge of outside world.

Such people are the rejects of the social world. These rejects are the main characters of Flannery O’ Conner’s “The Life You Save May Be Yours.” In this short story, O’ Conner uses a lot of irony to show the ignorance of these rural people. The irony used in this short story conveys the pure innocence of the backcountry people in that they have no clue how stupid that their actions may look to others.They do what they feel will be right, which make sense to them. But when others find that there are such words, like “inbreeding”, for the silliness that they call life they feel sorrow. But in this short story the character from the outside world, Mr. Shiftlet, is also an outcast in society and does not feel any remorse for the other characters.

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He plays along in their plans to be the same as years before and not to advance in technology and moral. The irony of this story develops in that Mr. Shiftlet agrees with the actions and offers of the other characters, the old woman and Lucynell. At first Mr.Shiftlet doesn’t seem to entertained by the offer of staying with and working for the old woman but he agrees to it after little thought. Also, when the old woman offers her daughter up to marriage with Mr.

Shiftlet he doesn’t consider the thought of love but instead the offer of money that comes along. When he takes her as his wife he soon after leaves her for the car that they are riding in. Then after leaving her and not looking back he picks up a hitchhiker and admits the remorse he feels for leaving his mother and making the mistake of taking on a life of wandering. Flannery has a way of making his audience uneasy at certain points during his story.

He makes them think for the characters and feel very unsafe with the characters’ actions.He makes the audience uneasy with the tragic reality of rural America. These people will be poor and not care for the rest of their lowly lives. They will continue to be ignorant of the world as others know it and not care to learn about the way they could be living.

The government will be their provider until they grow old and die.


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