Understanding Bacteria: Types, Functions, and Impact on Health

1. Note Sheet 15 – Bacteria: Part 1 & 2

2. What are bacteria? • Bacteria – single-celled organisms that do not have a nucleus • A bacteria organism is one single prokaryotic cell – that’s the whole organism • A bacteria’s only goal is to stay alive and make more bacteria • Bacteria are the smallest living things and they cover nearly every centimeter of the Earth

3. What is the structure of a bacteria cell? • Most bacteria have the following structures: a cell wall, a cell membrane, cytoplasm, DNA, and ribosomes

4. What are the 3 main types of bacteria?

5. What are the 3 main types of bacteria? • Bacteria are identified by one of 3 shapes: • Bacilli – rod-shaped bacteria (singular is bacillus)

6. Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells

7. What are the 3 main types of bacteria? • Bacteria are identified by one of 3 shapes: • Cocci – spherical-shaped (like a ball) bacteria (singular is coccus)

8. methicillin-resistant Staphylococcus aureus (MRSA)

9. What are the 3 main types of bacteria? • Bacteria are identified by one of 3 shapes: • Spirilla – spiral-shaped bacteria (singluar is spirillum)

10. Do all bacteria make you sick? • NO – Bacteria are everywhere in nature, but only a few cause disease • Many bacteria actually live inside of you and help you in different ways

11. Escherichia coli in the human intestines • E. coli normally colonizes an infant's intestines within 40 hours of birth, arriving with food or water or with the individuals handling the child • Harmless strains of E. coli benefit the host by producing vitamin K (necessary for blood coagulation) • They also prevent harmful bacteria from becoming established in the intestine

12. What causes disease? - Germ Theory of Disease • Thegerm theory of disease, also called the pathogenic theory of medicine, is a theory that proposes that microorganisms are the cause of many diseases • Although highly controversial when first proposed, it is now a cornerstone of modern medicine and clinical microbiology, leading to such important innovations as antibiotics and hygienic practices

13. How do bacteria make you sick? • Some bacteria live in your body tissues disrupting their function – symptoms are generally caused by the body’s defenses • EX. The bacteria that causes tuberculosis colonize lung tissue disrupting lung function • Some bacteria release poisons that harm the body • EX. Tetanus is caused by a neurotoxin produced by Clostridium tetani bacteria

14. Muscular spasms in a patient suffering from tetanus. Painting by Sir Charles Bell, 1809.

15. The discovery of antibiotics • In 1928, Alexander Fleming was investigating staphylococci. • In August 1928, Fleming went on vacation with his family. Before leaving he had stacked all his cultures of staphylococci on a bench in a corner of his laboratory. • On returning, Fleming noticed that one that the colonies of staphylococci culture was contaminated with a fungus, and bacteria that had immediately surrounded it had been destroyed • The fungus was from a group of fungi called Penicillum, and he called the bacteria-killing substance it produced penicillin

16. Discovery of Penicillin

17. How do bacteria make you sick? • Antibiotics – Substances that block the growth and reproduction of bacteria • One of the major reasons for the increase in life expectancy over the last 100 years is the use of antibiotics to cure bacterial infections

18. A test to see if a specific antibiotic will affect a strain of staph bacteria

19. Antibiotic Resistance – Too much of a good thing? • Many bacteria have developed resistance to certain antibiotics • The more we use antibiotics, the more we risk the development of resistant bacteria strains • Antibiotics are frequently prescribed unnecessarily, and taken irresponsibly • Antibiotics are used extensively in agriculture • In some cases, bacteria can be resistant to more than one type of antibiotic • Resistance is determined by genes, and can be transferred from one bacteria to another via transformation or transduction • Antibiotic resistance poses a significant problem for human health now and in the future

20. Bacteria Part 2

21. How do bacteria reproduce? • Binary Fission – process where a bacteria cell grows to double its normal size, copies its DNA, and divides into 2 identical cells • Some bacteria can divide as often as every 20 minutes

22. How do bacteria get energy? • Like you, most bacteria get energy by breaking down sugar • Bacteria don’t have mitochondria, so they don’t perform respiration exactly the same way that eukaryotic cells do • Glycolysis and fermentation – the process where glucose is broken down into either lactic acid or alcohol/CO2 releasing 2 ATP’s of energy • Other bacteria have light-absorbing pigments and can make their own food in a process similar to photosynthesis

23. How do humans control “bad” bacteria? • Sterilization – process of destroying bacteria using great heat or chemicals • Most bacteria cannot survive high temperatures for a long time • Cooking food to high enough temperature kills bacteria • Foods can be preserved for a long time by killing all the bacteria with heat and then placing the foods into sterile glass jars or cans

24. Canning Tomatoes250 lbs of tomatoes + 10-12 hours = 45 to 50 quarts of crushed tomatoes

25. How do humans control “bad” bacteria? • Bacteria grows more slowly at low temperatures, so refrigeration and freezing keeps food longer • Salt and vinegar prevent the growth of bacteria as well

26. Impact of Refrigeration • The refrigerator allows the modern family to keep food fresh for much longer than before. This allows a vastly more varied diet and improved health resulting from improved nutrition. Dairy products, meats, fish, poultry and vegetables can be kept refrigerated in the same space within the kitchen. • The refrigerator lets people eat more salads, fresh fruits and vegetables, without having to own a garden or an orchard. • Exotic foodstuffs from far-off countries that have been imported by means of refrigeration can be enjoyed in the home because of domestic refrigeration. • Freezers allow households to buy food in bulk: it can be eaten at leisure, and bulk purchase saves money. Ice cream, a popular commodity of the 20th century, could previously only be obtained by traveling long distances to where the product was made fresh, and had to be eaten on the spot.

27. Making Pickles • 6 Kirby cucumbers, cleaned, stemmed and halved, lengthwise1/2 cup of white vinegar2 tablespoons of salt1 tablespoon of black peppercorns1 tablespoon of coriander seeds3 cloves of garlic, minced1/2 cup of fresh dill • Place salt, peppercorns, coriander seeds, garlic and dill in a sterilized 1-quart Mason jar • Layer sliced cucumbers in jar, leaving 1/2 inch at the top • Pour in vinegar • Fill jar with water, seal with lid and shake for about a minute Refrigerate for six days, shaking daily

28. How do humans control “bad” bacteria? • Bacteria need a way into an organism to infect that organism • Hand-washing prevents bacteria from getting in the mouth • Nose hair and mucus prevent bacteria from getting into the airways through the nose • Keeping cuts clean and bandaged prevents bacteria from entering the bloodstream