Search in the document preview
Harmful micro-organisms and their impacts in human world
• Definition: • Micro-organisms : living creatures that are very small and
could only be seen under the microscope • Harmful micro-organisms : they will cause discomfort or
diseases to human body when invading the body and play an adverse effect in the environment.
This image cannot currently be displayed.
Classification Harmful micro-organisms can be divided as two groups,they are bacteria & small parasites Bacteria --The most common harmful microorganisms are bacteria --First discovered in 1683 --Today --- more than 1500 species of bacteria are identified
Structure of bacteria Size :Larger than virus
0.5 - 1.5 micron in diameter
seen with the aid of microscope
Existence : as single cell/ colonies
Shape : - rod shaped bacterium
- spherical bacterium
- spiral bacterium
- spherical in chains bacterium
Cell of bacteria --- surrounded by cell wall which maintains the shape of the cell and allows interchange of materials with the surroundings. --- the only organisms with prokaryotic cellular organization.
Prokaryotic bacteria --- lack a nucleus --- have no membrane envelope --- responsible for many diseases The illustration below depicts spiral shaped bacteria having whip-like flagella (protein filaments that propel the cells through their environment).
Nutrition a) mostly heterotrophic bacteria, feeding as saprophytes or as parasites - require organic nutrients e.g. carbonhydrate b) some are photo-autotrophic bacteria - require carbon dioxide as source of carbon and sunlight as their source of energy c) Some are chemo-autotrophic bacteria - use carbon dioxide Respiration a) Mostly aerobically when Oxygen is present, - Obtain energy from fermentation when oxygen is absent b) Few are strict anaerobes and die or form dormant spores when exposed to oxygen gas
Reproduction of bacteria ---- By an asexual process calledbinary fission
e.g. Growth of Streptococcus pneumoniae
This sequence begins at midnight (12:00am). First Frame Intermediate Frame Current Frame
Min 1 (12:00am) Min 100 (1:39am) Min 200 (3:19am)
The length of time between cell divisions is dependent on a number of factors including nutrient concentration, waste concentration,temperature, concentration of gases and more.
Endospores In adverse condition, a few species form endospores. The thick wall endospore protects the cell inside from dessication , certain chemicals (e.g. disinfectant) and from extreme of temperatures. When favourable condition comes, endospores will germinate
Myobacterium tuberculosis (TB) ----- caused by the bacteria Myobacterium tuberculosis ----- air borne
----- a chronic disease ----- patient will experience cough, malaise, weak, thin and blood streak sputum ----- commonly happened in poor, underdeveloped country Docsity.com
---- affects the intestinal tract ---- caused by a germ called Vibro cholera ---- The cholera germ is passed in the stools ---- spread by eating or drinking food or water contaminated by the fecal
waste of an infected person. ---- occurs more often in underdeveloped countries lacking adequate water
supplies and proper sewage disposal.
--- a bacteria in the stomach lining of patients with chronic gastritis and peptic ulcers.
--- flagellated corkscrew-shaped --- survives in the forbidding acid environment of the stomach
and duodenum by hiding in the mucus and neutralizing stomach acid in its local environment.
--- ulcers are increasingly believed related more to the presence of Helicobacter infection.
--- antibiotics are used in the successful treatment of peptic ulcers.
--- Quietly lurking under our beds, inside sofas and carpet --- too small to see without a microscope --- in the arachnid family which includes spiders,etc. --- feed on dead skin and sloughs from our bodies --- spend their whole lives in dark corner dust bunnies for hatching,
growing, eating, defecating, mating, laying eggs. --- make us itch and wheeze, develop severe allergies, itchy red. --- Breath in dust mites and you may have more serious symptoms like
difficulty in breathing or even a severe asthmatic attack.
--- water-borne pathogen --- can cause diarrhea or a more serious invasive liver abscess --- When in contact with human cells, these amebae are
cytotoxic. --- There is a rapid influx of calcium into the contacted cell, it
quickly stops all membrane movement. Internal organization is disrupted and the cell dies. The amoeba may eat the dead cell or just absorb nutrients released from the cell.
--- Commonly found in wild animals such as the beaver --- may infect unwary hikers and can also be contracted via contaminated foods --- It has a pair of identifiable nuclei when seen under microscope --- Giardia uses a ventral suction cup to attach to its host's intestinal epithelium --- a heavy infection of Giardia will block the important transport of nutrients across the epithelium.
Impact of harmful micro-organisms in human world - could bring a lot of diseases to human thus affect the productivity in the society 1. Pathogenic bacteria A relatively number of species of bacteria will cause many serious diseases to human. A) Mammalian diseases Bacterial diseases of mammals are transmitted in four main ways: i) Through the air: Airborne bacterial diseases - diphtheria, tuberculosis, bacterial pneumonia and whooping cough. ii) In food and water: Waterborne bacterial diseases - typhoid fever, gastroenteritis, bacterial dysentery, cholera, food poisoning Docsity.com
iii) By sexual contact - Syphilis, gonorrheoa iv) Through the skin - impetigo , postnatal fever are diseases caused by bacteria that enter the
body through the wounds and mucous membranes v) By animals - Vectors are sometimes involved in transmitting pathogenic bacteria. The bacteria that caused plague is transmitted to human by the rat flea. B) Plant diseases Some bacteria could cause disease/ death to plants which will endanger
the food chain to the human world. C) Other infection and infestation - can be transmitted by sexual contact e.g. candidiasis- caused by yeast, trichomoniasis - caused by a flagellated protozoa scabies and pubic lice -caused by parasitic arthropods