Unit 5 ~ Learning Guide

Transcription

1 Unit 5 ~ Learning Guide Name: INSTRUCTIONS Using a pencil, complete the following notes and questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test. 5.1 NOTES: BACTERIAL CLASSIFICATION Discovery of Bacteria It had long been suspected that which are too small to be seen with naked eye. But. A Dutch scientist, (1673), was the. He used a simple microscope to describe bacteria and protozoa with accurate drawings and descriptions and called these small creatures animalcules. He first observed small creatures in rain water, then confirmed these in saliva, vinegar, infusions and other substances. The progress in understanding the nature and importance of these tiny organisms has been slow. The existence of microbes was further confirmed by. Pasteur went on to make. His main achievements are the development of vaccines for anthrax disease, fowl cholera and rabies. He also made significant contributions in development of the pasteurization process and development of fermentation industries... Page 1 of 35

2 The Prokayotes The Kingdom prokaryotae (often referred to as ) consists of organisms with. Prokaryotic cells that typify the eukayota. In Greek the word and. Traditional classifications have placed the archea and bacteria into this single taxonomic kingdom due to their morphological similarity. In fact the two groups are extremely different, as different from each other biochemically as eukaryotes are from either group. Microbiologists now recognize that there are : a much smaller division called the Archaebacteria (Greek for ), a larger group called Eubacteria (Greek for ), and the Eukaryotes. Their small size, ability to rapidly reproduce (for example, the intestinal bacterium E. coli can reproduce by binary fission every 15 minutes), and diverse habitats/modes of existence make. Bacteria are wide spread in their occurrence. They are. Their kind and number vary according to locality and environmental conditions. Some bacteria are always present and contribute towards the natural flora. Others are present in specific environments such as hot springs, alkaline/acidic soil, highly saline environments, in highly polluted soils and waters. Archaebacteria The name comes from the root "archae" which means ancient. Archaebacteria are considered among. The archeans are life's extremists, occupying environments that "normal" organisms find too harsh such. They do not need oxygen or light to survive. Page 2 of 35

3 There are three groups of Archaea: 1. The live under anaerobic environments (e.g., marshes) where they produce methane. 2. require high salt concentrations (such as in Utah's Great Salt Lake). 3. live under hot, acidic environments (like those found in geysers) Eubacteria The Eubacteria and blue-green bacteria (once referred to as blue-green algae), or cyanobacteria are the. The name comes from the root "eu" which translates as. They are the most common forms of bacteria. There are approximately 12 different phyla... Page 3 of 35

4 Classifying Bacteria Bacteria can are classified by a number of different criteria: Most bacteria come in one of three different shapes. Some bacteria tend to organize into groups. Term Describing Bacterial Shape Picture of Bacterial Shape Prefix Describing Bacterial Arrangement Picture of Bacterial Arrangement 1. = 1. = e.g. diplococci are pairs of spherical shaped bacteria 2. = 2. = e.g. streptococci are chains of spherical shaped bacteria 3. = 3. = e.g. staphylococci are clusters of spherical shaped bacteria Page 4 of 35

5 Classifying Bacteria by Staining The is the most important staining procedure in microbiology. It is. Hence, it is a differential stain. Gram staining involves a four-part process, which includes: 1. crystal violet 2. the primary stain iodine 3. the mordant a decolourizer made of acetone 4. alcohol safranin, the counterstain. Gram negative and gram positive organisms are distinguished from each other. These differences affect many aspects of the cell, including the way the cell takes up and retains stains., which is then fixed in the cell with the iodine mordant. This forms a crystal-violet iodine complex which remains in the cell even after decolorizing. It is thought that this happens because the cell walls of gram positive organisms include a protein-sugar complexes called. This layer makes up 60-90% of the gram positive cell wall. Decolorizing the cell causes this thick cell wall to dehydrate and shrink, which closes the pores in the cell wall and prevents the stain from exiting the cell. At the end of the gram staining procedure, Page 5 of 35

6 Gram negative cells also take up crystal violet, and the iodine forms a crystal violetiodine complex in the cells as it did in the gram positive cells. However,. Peptidoglycans are present in the cell walls of gram negative organisms, but they only comprise 10-20% of the cell wall. Gram negative cells also have an outer layer which gram positive organisms do not have; this layer is made up of lipids, polysaccharides, and proteins. Exposing gram negative cells to the decolourizer dissolves the lipids in the cell walls, which allows the crystal violet-iodine complex to leach out of the cells. This allows the cells to subsequently be stained with safranin.. Classifying Bacteria by Nutrition Bacteria are classified on the basis of their method of. Traditional classifications include groups. 1. Chemosynthetic Bacteria - Example: Pseudomonas aeruginosa 2. Photosynthetic Bacteria -. Cyanobacteria are the major group of photosynthetic bacteria. Some early cyanobacteria may have formed the, transforming our planet from one with an oxygen-free atmosphere, to the modern one that has a significant amount of oxygen present. Example: Heliobacteria from soil.. 3. Saprophytic bacteria are heterotrophic bacteria that 4. Parasitic bacteria are heterotrophic bacteria that. Page 6 of 35

7 5. Other Bacteria are classified as. Decomposers play an important role in nature as they. They are an important part of the food chain. In summary, bacteria use all modes of nutrition. Some bacteria are autotrophic (able to produce their own energy) by photosynthesis and others by chemosynthesis. Most types of bacteria however, are heterotrophic by absorption.. Others absorb nutrients from other living things and are known as parasites. 5.1 PRACTICE: BACTERIAL CLASSIFICATION 1. Recent classification schemes have determined there are three domains of life: a. What are these domains called? (3 marks) b. Which if these domains contain bacteria? (2 marks) 2. What distinguishes the domains that contain bacteria from the one that does not? Hint: think cellular structure. (2 marks) Page 7 of 35

8 3. Please classify each of the following bacteria using the terms gram positive, gram negative, staphylo-, strepto-, diplo-, -cocci, -bacilli, -spirilli. (12 marks) Shape/Organization Gram Stain Colour Classification pink Example: gram negative, monospirillum *note: mono = one = individual bacteria purple purple pink pink 4. A gram positive bacteria is likely to have a great deal more in its cell wall than a gram negative bacteria and thus, it will bind to and retain the Gram stain better. (1 mark) 5. Chemosynthetic bacteria are said to be because they can produce energy and organic compounds for themselves, whereas most other bacteria are as they obtain energy and organic compounds by feeding off of other living things. (2 marks) Page 8 of 35

9 5.2 NOTES: BACTERIAL STRUCTURE - but don't let their small size and seeming simplicity fool you. They are an amazingly complex and fascinating group of organisms. Bacteria, since they are prokaryotes, that normally occur in a chloroplast or mitochondrion of eukaryotes will. Bacterial and arrayed in a region of the cell known as the. Scattered within bacterial cytoplasm are numerous which are often used to carry foreign DNA into other bacteria for recombinant DNA engineering. The, the structures where proteins are assembled. All bacteria also have a, which is usually surrounded by a. Page 9 of 35

10 Bacterial Structure Associated Function plasmid capsule made up of polysaccharides (complex sugars. and protects it from drying out cell wall gives cell its shape and surrounds the cytoplasm plasma membrane a layer of phospholipids and proteins that allows certain materials into and out of the cell ribosome Only type of cell organelle found in bacteria. Small factories that translate the genetic code into proteins. fimbriae Small hair-like projections that emerge from the cell membrane. cytoplasm Or protoplasm, this is where the functions of cell growth, cellular metabolism and replication are carried out. It is a gel-like material that is composed of water, enzymes, nutrients, wastes and gasses and cell structures such as the ribosomes, chromosomes, and plasmids. nucleoid A region of the cytoplasm where the chromosomal DNA is located flagella Hair-like structures that. Not all bacteria have flagella. Page 10 of 35

11 Endospores Bacteria = Microorganisms sense and adapt to changes in their environment. When favored nutrients are exhausted, some bacteria may become motile to seek out nutrients, or they may produce enzymes to exploit alternative resources.. This complex developmental process is. Endospores can survive environmental assaults that would normally kill the bacterium. These stresses include. The extraordinary resistance properties of endospores make them of particular importance because they are not readily killed by many antimicrobial treatments. A variety of different microorganisms form spores or cysts, but the endospores of bacteria are by far the most resistant to harsh conditions. Page 11 of 35

12 5.2 PRACTICE: BACTERIAL STRUCTURE 1. Please draw a simplified diagram of a bacteria cell being sure to include and label the structures listed below. Please include a brief description of the structure's function beside the label. Please be neat. (10 marks) o nucleoid o plasmid o cytoplasm o cell wall o fimbriae o ribosomes o flagella o capsule o plasma membrane Page 12 of 35

13 5.3 NOTES: BACTERIAL REPRODUCTION Binary Fission is the by division into two approximately equal parts. This method of cellular reproduction occurs only in prokaryotes (bacteria and archaeans). As one might expect, the volume of the two daughter cells produced is initially half that of the parent cell before the division. But each daughter cell does contain a complete copy of the parental chromosome. Before fission can occur,, which is circular. Each chromosome then affixes itself to the cell membrane. As the cell stretches out during division, the two chromosomes move apart, and one passes into each of the two daughter cells. The actual physical division of the cell into two compartments occurs when across the middle of the cell. Page 13 of 35

14 Exchange of Genetic Information. When bacteria exchange DNA it has a similar effect to as there is a.. There are three ways in which bacteria exchange DNA male cell passes DNA to the female cell by means of a conjugation tube i.e., sex pilus bacterium takes up DNA released by dead bacteria bacteriophages carry DNA from one cell to another Page 14 of 35

15 5.3 PRACTICE: BACTERIAL REPRODUCTION 1. Please identify which process in being represented by each picture below (transduction, binary fission, conjugation, and transformation) and then provide a brief description of the process in the box beside the picture. (8 marks) Various Processes that Affect the Genetic Composition of Bacteria Page 15 of 35

16 5.4 NOTES: BACTERIAL METABOLISM The diversity of prokaryotes is expressed by their, and this feature allows prokaryotes to flourish in all habitats on earth. Bacteria have been found that can live at and in those that would. They "eat". There is even a species of bacteria that can withstand blasts of radiation 1,000 times greater than those that would kill a human being. Most bacteria are. These bacteria. These bacteria utilize cellular respiration to produce energy. Cellular Respiration is the breakdown of sugar molecules with the use of oxygen to release energy. C6H12O6 + 6O > 6 H2O + 6 CO2 + Energy Some bacteria are called a. Photosynthesis is Cyanobacteria is an example of a photosynthetic bacteria. 6 CO2+ 6 H2O light >C6H12O6 + 6 O2 b.. Fermentation is. Bacteria will ferment by one of these two equations. Pyruvic Acid + NADH >Lactic Acid + NAD + (also used by animals) Pyruvic Acid + NADH >Alcohol + CO2 + NAD + (also used by plants) Page 16 of 35

17 Other bacteria are. Facultative anaerobes are. These bacteria will use cellular respiration if oxygen is present and fermentation if oxygen is not present. Beneficial Bacteria Bacteria provide us with products which we depend every day. For example, bacteria. Some bacteria are used to make pickles and sauerkraut, and some make vinegar from wine. Bacteria are also used in industry. One type of bacteria can digest petroleum, which makes them. Some bacteria remove waste products and poisons from water. These bacteria can be. Others can even from the ground. Still others have been and chemicals through techniques of genetic engineering. Many kinds of bacteria develop a symbiotic relationship with other organisms in which. Our intestines are inhabited by large numbers of bacteria including E. coli. In the intestines, the. Bacteria. Gradually, the material being decomposed is recycled, enriching the soil thereby providing valuable nutrients required for plant growth. Page 17 of 35

18 5.4 PRACTICE: BACTERIAL METABOLISM 1. Please compare and contrast the terms obligate anaerobe and obligate aerobe. (3 marks) 2. Would it technically be incorrect to refer to a facultative anaerobe as a facultative aerobe? Please explain your answer? (2 marks) 3. Tired of always being portrayed as the "bad guys" (see image below), a group of bacteria have hired you as their new public relations (PR) representative. Please design a PR device to improve the image of bacteria in the eyes of the human population. You may design a poster, radio commercial (script), TV commercial (post on YouTube), song (send lyrics or post on YouTube), comic strip, children's colouring pages or any other device that you think will help to inform the public of some of the benefits of bacteria. (10 marks) Page 18 of 35

19 5.5 NOTES: BACTERIAL DISEASE Symbiosis in Bacteria When bacteria live in association with other organisms they are known as. There are, and different groups of bacteria employ all three. 1. In (+/+) symbiotic relationships, from the relationship. For example, nitrogen fixing bacteria live in nodules of legumes. They provide the plant with nitrogen and the plant supplies the bacteria with other nutrients. 2. In a (+/0) relationship,. Bacteria live on human skin and do not harm us, but benefit from the warm moist environment. 3. A (+/-) relationship means that. Parasitic bacteria harm the host and. Some parasitic bacteria use a human host, so the study of bacteria is of great importance to human beings. Most bacteria however are not pathogenic. Useful bacteria include: decomposers nitrogen fixing bacteria vitamin producing bacteria bacteria used to make insulin (E.coli) and growth hormones Some bacteria are used to make antibiotics (e.g. Streptomycin) There are many industrial bacteria. Such as bacteria. Bacteria. Scientists use bacteria in genetic research because they only have 1 chromosome, are easy to grow, and have a short life cycle Page 19 of 35

20 Harmful Bacteria and Koch Postulates As stated previously most bacteria are which means they are. Many actually help us in some way (digestion, protection). There are relatively few bacteria that are considered to be pathogenic or disease causing. Pathogenic or disease causing bacteria. Bacteria may produce endotoxins and exotoxins which elicit an immune response. Koch s Postulates was a German Bacteriologist who came up with the rules to prove that an organism is responsible for a particular condition or disease. He formulated the "germ theory of disease". He isolated typical rod-shaped bacteria with squarish ends (bacilli) from the blood of sheep that had died of anthrax. Then he Discovered bacteria that caused tuberculosis and cholera. Robert Koch 1. A specific organism can always be found in association with a given disease The pure culture will produce the disease when inoculated into susceptible animal. 4. Page 20 of 35

21 Koch and his colleagues invented many techniques concerning inoculation, isolation, media preparation, maintenance of pure cultures and preparation of specimens for microscopic examination. Examples of Bacterial Disease 1. : Strept throat Rheumatic Fever Pneumonia Tuberculosis 2. : Staph Pimples Leprosy flesh eating disease 3. : tetanus Botulism meningitis 4. : Typhoid fever cholera, Salmonella E. coli 5. : Gonorrhea Syphilis Lines of Defense The human body constantly faces attack from foreign invaders that can cause infection and disease. These invaders range from living microbes such as bacteria, fungi, and viruses, to nonliving toxins, chemicals, and drugs. Fortunately, the body has a number of external and internal safeguards that prevent most dangerous invaders from entering and causing harm. The is non specific and aims to stop microbes from entering the body. The preventing Page 21 of 35

22 penetration by microbes. If the skin is cut then the blood produces a. The surfaces of the body the skin, digestive system, and the lining of the nose are covered by a called the normal body flora. They help to protect a host from becoming infected with more harmful micro-organisms by acting as a physical barrier. It means that the harmful microbes have to compete with the normal body flora for nutrients. The average human gut contains around 1 kg of these good bacteria which is equivalent to one bag of sugar. The respiratory system the nose and passageways leading to the lungs is lined with cells that produce sticky fluid called, where they are either coughed or sneezed out or swallowed and then passed out of the body in feces. The body produces several antimicrobial substances that kill or stop microbes from growing. For example the. The which destroys many of the microbes that enter the body in food and drink. Urine as it flows through the urinary system flushes microbes out of the bladder and urethra. If microbes do manage to get inside the body then the is activated. This is also non-specific as it stops any type of microbe.. They send out pseudopodia which allows them to. Phagocytes release digestive enzymes which break down the trapped microbes before they can do any harm. This process is called phagocytosis. The. It is regarded as a threat by the immune system and is capable of stimulating an immune response. Antigens are proteins that are found on the surface of the pathogen. Antigens are unique to that pathogen. The whooping cough bacterium, for example, will have different antigens on its surface from the TB bacterium. When an antigen enters the body, against it. It is like a battle with the army (antibody) fighting off the invader (antigen). A type of white blood cell called. Each antibody has a unique binding site shape which locks onto the specific shape of the antigen. The antibodies destroy the antigen (pathogen) which is then engulfed and digested by macrophages. Once the invading microbes have been destroyed the immune response winds down. Once a person has had a disease they don t normally catch it again because the body produces Page 22 of 35

23 . The memory cells remember the microbe which caused the disease and. The pathogen is quickly destroyed preventing symptoms of the disease reoccurring. What are Antibiotics? Antibiotics are. The first antibiotic was discovered by in 1928 in a significant breakthrough for medical science. The development of antibiotics is probably the largest advance in medicine in the 20th century, and has saved millions of lives worldwide from infections such as TB. Since, a wide range of antibiotics has been developed. Originally produced from molds and fungi, many antibiotics are now produced synthetically. Antibiotics are not effective against infections caused by viruses, so if you go to your doctor with a viral illness such as a cold, flu or a viral sore throat, antibiotics have no role to play.. For example, if you have a streptococcal throat, penicillin may be prescribed.. These are called broad. This type of antibiotic is often used to treat respiratory or urinary tract infections because it is difficult to establish what specific bacteria are causing the condition. Antibiotics can be classified into five main categories: 1. PENICILLINS including: Amoxycillin, Amoxil, Augmentin, Calvepen, Clonamox, Floxapen 2. CEPHALOSPORINS including: Cefodox, Distaclor, Keflex, Suprax, Zinnat 3. AMINOGLYCOSIDES including: Genticin 4. TETRACYCLINES including: Clinimycin, Hostacycline, Minocin, Vibramycin 5. OTHERS including: Ciproxin, Erymax, Erythrocin, Flagyl, Ipral, Klacid, Zithromax Page 23 of 35

24 The choice of antibiotic depends on the How do antibiotics work? An antibiotic is a selective poison. It has been chosen so that it will. Each different type of antibiotic affects different bacteria in different ways. Essentially, antibiotic drugs, allowing the body s immune system to deal with the infection. For example, an antibiotic might inhibit a bacterium's ability to turn glucose into energy, or its ability to construct its cell wall. The most commonly used antibiotics, penicillins and cephalosporins, are bactericidal and work by. When this happens, the bacterium dies instead of reproducing. Considerations for the use of antibiotics: The antibiotic. Some people are. Some antibiotics could kill off useful bacteria.. May cause resistant strains to develop. Other biocides include: Sulfur disinfectants. Drugs, antitoxins, various bacteriocides, Chart of various antibiotics: Page 24 of 35

25 Antibiotic Resistance Antibiotics kill or inhibit the growth of susceptible bacteria. Many diseases that once killed people can now be treated effectively with antibiotics. An antibiotic is a. Sometimes one of the bacteria survives because it has the ; that one bacteria can then. Exposure to antibiotics therefore provides selective pressure, which makes the surviving bacteria. In addition, bacteria that were at one time susceptible to an antibiotic can through of their genetic material or by acquiring pieces of DNA that code for the resistance properties from other bacteria. Although bacteria are capable of developing a number of factors may speed up the development of resistance. These include: 1. in humans. 2. Widespread use of antibiotics in the rearing 3. as prescribed by your doctor. The danger of widespread resistance to antibiotics is that (so-called 'superbugs'). There is huge concern among doctors that eventually these 'superbugs' could cause untreatable infections in the otherwise healthy populations. Most infectioncausing bacteria can become resistant to at least some antibiotics. Bacteria that are resistant to many antibiotics are known as multi-resistant organisms (MROs). How can it be prevented? 1. like a cold or the flu. 2. Discard any leftover medication once you have completed your prescribed course Page 25 of 35

26 of treatment. 3.. Complete the prescribed course of treatment even if you are feeling better. 4. Do not take antibiotics prescribed for someone else. 5. Stop the use of antibacterial hand soaps and sanitizers. Wash your hands with regular soap and water instead. This first bacterial streak plate shows the effect of antibiotic disks on bacteria. There is no growth near the white disks. On this second streak plate the bacteria now exhibit resistance to the antibiotic disks. Page 26 of 35

27 5.5 PRACTICE: BACTERIAL DISEASE 1. The human body has three lines of defense against pathogens (disease-causing agents): a. Please identify and briefly describe the first line of defenses. (2 marks) b. Please identify and briefly describe the second line of defenses. (2 marks) c. Please identify and briefly describe the third line of defenses. (2 marks) Page 27 of 35

28 2. You often hear people express concern that if they use antibiotics inappropriately that "they will become resistant to the antibiotic". While a person is correct in being concerned about the inappropriate use of antibiotics, this particular statement reflects a severe misconception of what "antibiotics resistance" is. What does antibiotics resistance refer to and how does the inappropriate use of antibiotics contribute to its existence? Please include terms such as mutation, selective pressure/natural selection, survival of the fittest and next generation in your answer. (5 marks) ~ END OF BIOLOGY 11 UNIT 5 LEARNING GUIDE ~ Page 28 of 35

29 UNIT 5 ANSWER KEY 5.1 PRACTICE: BACTERIAL CLASSIFICATION 1. Recent classification schemes have determined there are three domains of life: a. What are these domains called? (3 marks) Archaea, Bacteria, Eukaryota b. Which if these domains contain bacteria? (2 marks) Archaea and Bacteria Page 29 of 35

30 2. What distinguishes the domains that contain bacteria from the one that does not? Hint: think cellular structure. (2 marks) The domains that contain bacteria (Archaea and Bacteria) includes only prokaryotic cells that lack a nucleus and other membrane-bound organelles. In contrast, the domain that does not contain bacteria (Eukaryota) includes only eukaryotic cells that generally have a nucleus and other membrane-bound organelles. 3. Please classify each of the following bacteria using the terms gram positive, gram negative, staphylo-, strepto-, diplo-, -cocci, -bacilli, -spirilli. (12 marks) Shape/Organization Gram Stain Colour Classification pink Example: gram negative, monospirillum *note: mono = one = individual bacteria purple gram positive streptobacilli purple gram positive staphylococci pink gram negative staphylobacilli pink Gram negative streptococci Page 30 of 35

31 4. A gram positive bacteria is likely to have a great deal more in its cell wall than a gram negative bacteria and thus, it will bind to and retain the Gram stain better. (1 mark) 5. Chemosynthetic bacteria are said to be because they can produce energy and organic compounds for themselves, whereas most other bacteria are as they obtain energy and organic compounds by feeding off of other living things. (2 marks) 5.2 PRACTICE: BACTERIAL STRUCTURE 2. Please draw a simplified diagram of a bacteria cell being sure to include and label the structures listed below. Please include a brief description of the structure's function beside the label. Please be neat. (10 marks) o nucleoid o plasmid o cytoplasm o cell wall o fimbriae o ribosomes o flagella o capsule o plasma membrane Page 31 of 35

32 5.3 PRACTICE: BACTERIAL REPRODUCTION 1. Please identify which process in being represented by each picture below (transduction, binary fission, conjugation, and transformation) and then provide a brief description of the process in the box beside the picture. (8 marks) Various Processes that Affect the Genetic Composition of Bacteria Binary Fission - genetic material replicated then cell divides into two identical (barring mutation) daughter cells Transduction - viral vector carries genetic material from one bacteria to another during the process of infection Transformation - bacteria picks up random genetic material from its environment Conjugation - plasmid (genetic material) is transferred from one bacterial cell to another via a conjugation bridge formed by a pilus/fibriae Page 32 of 35

33 5.4 PRACTICE: BACTERIAL METABOLISM 1. Please compare and contrast the terms obligate anaerobe and obligate aerobe. (3 marks) Obligate means "required" or "restricted to" an obligate anaerobe must metabolize and live without oxygen whereas an obligate aerobe must metabolize and live with oxygen. 2. Would it technically be incorrect to refer to a facultative anaerobe as a facultative aerobe? Please explain your answer? (2 marks) Facultative means it can occur optionally but is not restricted to a particular condition or environment. A facultative anaerobe can function in the absence or presence of oxygen. Likewise, a facultative aerobe can function in the presence or absence of oxygen. Thus, the terms can be correctly used interchangeably. 3. Tired of always being portrayed as the "bad guys" (see image below), a group of bacteria have hired you as their new public relations (PR) representative. Please design a PR device to improve the image of bacteria in the eyes of the human population. You may design a poster, radio commercial (script), TV commercial (post on YouTube), song (send lyrics or post on YouTube), comic strip, children's colouring pages or any other device that you think will help to inform the public of some of the benefits of bacteria. (10 marks) Approachesand answers may vary but may include pointing out the benefits of bacteria such as: o o o o o o o Commensal bacteria preventing colonization of human body by harmful bacteria Commensal bacteria helping in digestion and vitamin production Use in food manufacture such as yogurt, cheese, sour cream, vinegar, and pickles Use in bioremediation of oil spills and mining sites Use in recycling/decomposition of dead matter and nitrogen-fixation. Use in scientific research. Use in production of insulin, human growth hormone and Factor VIII for use in human medicine. Page 33 of 35

34 5.5 PRACTICE: BACTERIAL DISEASE 1. The human body has three lines of defense against pathogens (disease-causing agents): a. Please identify and briefly describe the first line of defenses. (2 marks) Non-specific barriers including: o Physical skin and mucus o Chemical tears and saliva, stomach acid b. Please identify and briefly describe the second line of defenses. (2 marks) Non-specific including: o Cells phagocytes c. Please identify and briefly describe the third line of defenses. (2 marks) Specific including: o T and B Cells that work together to destroy specific pathogens using antibodies produced by B cells 2. You often hear people express concern that if they use antibiotics inappropriately that "they will become resistant to the antibiotic". While a person is correct in being concerned about the inappropriate use of antibiotics, this particular statement reflects a severe misconception of what "antibiotics resistance" is. What does antibiotics resistance refer to and how does the inappropriate use of antibiotics contribute to its existence? Please include terms such as mutation, selective pressure/natural selection, survival of the fittest and next generation in your answer. (5 marks) Answers should include the following key points: o o o o Antibiotic resistance refers to a strain of bacteria being resistant (not significantly harmed or controlled by) an antibiotic not to a human being resistant to the antibiotic. Indeed, humans should be resistant to all antibiotics or else their use would kill our cells and therefore, us. Bacteria become resistant to an antibiotic through random mutation. This makes them more "fit" in scenarios where an antibiotic is being used. When antibiotics are used inappropriately (not taken for the full recommended course) or excessively we are essentially selecting for the naturally occurring resistant mutants. We kill off the non-resistant bacteria and all that are left are the stronger Page 34 of 35

35 o more resistant bacteria. These bacteria now have less competition and can rapidly reproduce and take over the organism they are infecting. Page 35 of 35