Microorganisms Flashcards
Why are viruses not considered living species
Do not consist of cells
Cannot reproduce independently
Cannot perform respiration because they don’t have mitochondria
Can survive long periods as crystals
What is the basic structure of a virus
Very small
Comprised of nucleic acid surrounded by protein capsule
Contain DNA or RNA, never both
They are acellular - do not have nucleus, cytoplasm and organelles
Some enclosed in sheath of protein and lipid molecules
What are the general characteristics of viruses
They are obligate intracellular parasites = can only reproduce inside a living cell
Can infect bacterial cells, these viruses are known as bacteriophages
All pathogenic
Reproduce by changing the host cells genetic material into viral DNA or RNA
Viruses are host specific, what does this mean?
They are capable of living in certain species
Which kingdom does bacteria belong in
Kingdom monera
What lifestyle do bacteria have
Can be autotrphic, heterotrophic, and pathogenic
What is the basic structure of bacteria
Smallest and simplest living organisms
Unicellular but cells can clump together to form filaments
Have a cell wall made from polysaccharides, proteins and lipids
Some have a slime layer to protect from dessication and our immune system
Prokaryotic = no true nucleus
DNA is concentrated in one area known as the nucleoid
Have thread like flagella for swimming
What are the different shapes of bacteria that can be found
Vibrio = comma shaped
Spirillium = spiral
Coccus = round
Bacillus = rod shaped
What are the general characteristics of bacteria
All unicellular
Prokaryotic
Autotrphic bacteria produce through photosynthesis or chemosynthesis
Most bacteria are heterotrophic; they get their food by being either parasitic, saprotrophic, or mutualistic
Reproduce asexually by binary fission
How can bacteria be useful to us
Drive nutrient cycles e.g: nitrogen cycle
Involved in food webs
Can have mutualistic relationships e.g: in our guts
Economic use e.g: sewage treatment
Decomposes
How can bacteria be harmful to us
Pathogenic
What is the basic structure of protists
All eukaryotic
Unicellular or multicellular
Mostly aquatic
Most contain cellulose cell wall but diatoms have capsules of silica
Can reproduce asexually through binary fission or sexually
What are the 3 Main groups of protists
Protozoa - animal like, unicellular and heterotrophic e.g: amoeba, paramecium, plasmodium
Algae - plant like, unicellular/multicellular, autotrophic e.g: phytoplankton - euglena and diatoms and kelp
Slime moulds and water moulds - fungus like, multicellular and heterotrophic
What is the basic structure of fungi
Can be macroscopic (multicellular) e.g: mushroom, or microscopic (unicellular) e.g: yeast
Have cell walls made from chitin
Heterotrophic
Eukaryotes
A few are parasites e.g: athletes foot and ring worm
Others live mutualistically e.g: lichens
What is Rhizopus
A multicellular mass of filaments where each each individual filament is known as hyphae
What is the structure of a rhizopus
All the filaments together are known as mycelium
Mycelium is vegetative - it has non-reproductive parts and sporangia are the reproductive parts
The reproductive structures produce spores which are wind dispersed
Terrestrial fungus (live on land; cool and dry conditions)
Three types of hyphae that make up mycelium: stolons, rhizoids and sporangiophores
Rhizopus is thallus because there are no roots, stems or leaves
What importance do microorganisms have as producers
Some bacteria can photosynthesise
Other bacteria can make organic compound from chemicals (chemosynthesis)
Chemosynthesis is only energy supply to ecosystems found at deep sea vents
Photosynthesising protists important in oceans
These microorganisms capture energy and pass it to consumers
What importance do microorganisms have as decomposes
Bacteria and fungi = main decomposers
Remove dead plant and animal matter from environment
Release nutrients from the dead organisms for re-use
What role do microorganisms play in the nitrogen cycle
Lots of nitrogen in air but it’s unavailable for plants and animals to use
Bacteria in soil and root nodules can convert nitrogen to nitrates
Plants use the nitrates to create plant protein
Animals eat plants and create animal protein from the plant protein
Animals return nitrogen into soil a urea or ammonia
What is the role of microorganisms in mutualistic symbiotic relationships
Nitrogen fixing bacteria in plants convert nitrogen into nitrates that plants can use, bacteria get carbohydrates and place to reproduce in return
E.coli lives in human gut and produces vitamin k which humans need for blood clotting, in return bacteria gets food and a place to live
What is fermentation
A process in which microorganisms undergo anaerobic respiration, converting glucose into carbon dioxide and ethanol
What is an example of traditional biotechnology
African people use fermentation to make amasi and umqombothi
What are examples of biotechnology in today’s food industry
Making beer - yeast ferments to create alcohol and carbon dioxide
Making wine - traps are stomped into pulp and ferment because of yeast cells in the air
Baking bread - Carbon dioxide created by yeast causes doubt to rise
Making cheese - lactic acid bacteria convert lactose into lactic acid
What economic use does bacteria have
Production of food by fermentation
Decomposition of sewage
Industrial production of enzymes, ethanol and perfumes
Production of antibiotics and steroids
Biological pest control - bacteria used to kill pests instead of pesticides
Bioremediation - getting rid of poisonous waste products
What economic use do protists have
Algae =source of food e.g: seaweed
Gelatine is harvested from algae and used in making jelly and agar
Good source of minerals in supplements and fertilisers
What economic use do fungi have
Can be eaten as foods e.g: mushrooms
Yeast used in production of bread, wine and beer
Production of some cheeses
Production of antibiotics
What are the effects of HIV/AIDS
Decreases CD4 count and immune system weakens
Flu like symptoms appear as CD4 count drops
Eventually opportunistic diseases e.g:TB and pneumonia strike
Infection now becomes AIDS
Death caused from one or more opportunistic diseases
What effects does HIV/AIDS have on SA’s economy
Mostly affects people in prime working years
Loss of workers = negative effect
Mining industry has high infection rate = indirect revenue loss due to absenteeism
Direct loss of revenue because of medicine and resources needed to take care of AIDS orphans
What effects does HIV/AIDS have on children and families
Babies born HIV positive because of HIV positive parent
Breadwinner can die of HIV = children abandoned/orphans
These children get separated from their families and are institutionalised
How do HIV cells reproduce
HIV attaches to helper-T cells
Uses reverse transcriptase to make DNA of itself
Viral DNA instructs host nucleus to make many parts of HI Virus
How can HIV/AIDS be managed through testing
Test to know your HIV status and then to take take the necessary precautions and medications
How can HIV/AIDS be managed through treatment
No cure, but treatment available to decrease viral load and increase CD4 count
Treatments: 1. ARVs to decrease viral load
2. Healthy diet to support immune system
3. Treatment of opportunistic diseases as required
4. PEP (post exposure prophylaxis) treatment within 24 hours of exposure
How can prevention help in the management of HIV/AIDS
get educated aboutHIV/AIDS and take preventative measures to not get HIV/AIDS
1. Avoid sexual intercourse
2. Be faithful to one partner
3. Practise safe sex
4. Avoid direct contact with blood
What are some beliefs and attitudes associated with HIV/AIDS
Carries stigma because it is life threatening, associated with negative social behaviour e.g: prostitution and requires a strong therapy that negatively affects external appearance
Stigma can lead to loss of partner, loss of job and loss of dignity
What are some common myths associated with HIV/AIDS
HIV can be transmitted through sneezing and mosquito bites
An HIV positive person can become resistant to HIV by having intercourse with a virgin
What is tuberculosis
Infectious disease caused by mycobacterium tuberculosis bacteria that mainly affects the lungs, but can also occur in other organs.
How is TB spread
Airborne disease - transmitted through small respiratory droplets
Which factors contribute to SA’s high TB infection growth rate
High rates of AIDS (TB is an opportunistic disease)
Malnutrition/poor diet in rural populations (immune system not strong bc lack of nutrients)
Overcrowding
Lack of medical infrastructure
Lack of education in rural population
What are the effects of TB
Bacteria reproduce causing infection in lung
Immune system can prevent TB from spreading if it is strong enough
If immune system is weak, TB becomes active where pneumonia occurs repeatedly and disease spreads to other parts of body
Get symptoms of coughing, tiredness, weight loss, night sweating
What effects does TB have on family and community
Loss of income because TB patient is off work for some months
If TB patient dies = loss of breadwinner
Stigma to having TB
May infect other family members
How does treatment help in managing TB
6 month antibiotic course can be taken
Can’t infect others while on this course
Some stop taking antibiotics because they feel better = cause drug resistant TB
DOTS programme (directly observed treatment, short-course) helps in making sure people eat their treatment everyday
How can prevention help in managing TB
Population can be educated on importance of healthy diet, hygienic living and fresh air
Babies can be vaccinated to build their immune system
Better immune system = disease won’t spread
Why would an organ transplant patient be susceptible to TB
After transplant they’re given immunity suppressants to prevent body from rejecting the new organ, but immunity suppressants also means that opportunistic diseases can strike
What is the difference between drug resistant, multi-drug resistant and extreme drug resistant TB
DR: don’t respond to the medication
MDR: don’t respond to at least 2 of the available medication
EDR: don’t respond to any of the available medications
What causes drug resistant TB
Poorly managed use of the antibiotics
What causes malaria and how is it transmitted
caused by parasitic protist genus plasmodium
Transmitted by Anopheles mosquito
In which regions is it popular
In tropical and sub-tropical regions
Malaria has 2 hosts, how does this work
Malaria needs both mosquitos and humans to reproduce
When mosquito sucks blood of infected person, malaria enters mosquito, multiplies and moves to mosquito’s salivary glands
When mosquito sucks blood from another person it injects saliva to stop the human’s blood from clotting
Malaria enters the new person and multiplies in the liver and blood cells
What are some symptoms of malaria
Flu like symptoms
Pain in the back and legs
Abdominal pain
Nausea and vomiting
Can lead to death especially in children
How does malaria affect the economy
Treatment for malaria is expensive
Malaria patient is sick = off work or can die = loss of breadwinner
How can malaria be prevented
Eliminate mosquito:
Spray inner walls of house with DDT (insecticide)
draining swamps
Putting film of oil on water harbouring the vectors
Stop them from biting:
Sleep under mosquito net
Wear long sleeve at night
Use bug spray
Take prophylactic medication
What is an immune response
The way in which an organism protects itself from pathogenic viruses, bacteria, protist or fungi
How does immune response work in plants
Only have natural immunity
Release chemicals such as salicylic acid which travels throughout the plant to warn other cells of danger (those cells produce other chemicals)
The infected cells are destroyed to prevent infection from moving
What are examples of natural immunity in humans
Skin is sealed off = first line of defence
Coughing and sneezing reflexes blast pathogens out from our airways
Tears are antiseptic = wash bacteria from our eyes
Inflammation and fever slow multiplication and spread of pathogen
How does acquired immunity work
After pathogens have penetrated
Pathogens have antigens on their surfaces and leucocytes identify pathogens using these antigens
Leucocytes destroy or neutralise the pathogen
Leucocytes: lymphocytes and phagocytes
Where do lymphocytes occur
Spleen, lymph glands and blood
What are the 2 types of lymphocytes
B-lymphocytes
T-lymphocytes
How do B-lymphocytes work
Have receptor proteins which bind to specific antigens on pathogen
B-lymphocyte recognises the pathogen as foreign and reproduces more B-lymphocytes
These B-lymphocytes produce antibodies which attach to matching antigens and do one of the following:
1. Mark the pathogen for ingestion by phagocyte
2. Cause pathogens to clum together which makes them inactive
3. Cause pathogen cell to burst
How do T-lymphocytes work
Recognise and destroy cells infected by a virus
Virus hides in host cell, therefore B-lymphocytes cannot find them
Antigens of virus are on host cell so T-lymphocytes are able to identify and destroy them
CD4 cells = type of T-lymphocyte
He does a person become immune to an infection
When they get infection for first time B-lymphocytes and T-lymphocyte fight the infection
Some T and B-lymphocytes have memory cells that stay in the blood and immediately recognise the pathogen when a person is re-infected = faster response = don’t become ill = immune
How do phagocytes work
Large amoeba like white blood cells
Engulf the pathogens = phagocytosis
Where are phagocytes produced
Red bone marrow
How do antibodies (produced by B-lymphocytes) help phagocytes
Pathogens marked for phagocytosis
Pathogens clumped together and inactive
What is immunisation
The administration of a vaccine to develop immunity to a disease
How do vaccines work
Dead or weakened form of disease is injected and body produces its own antibodies or the antibodies of another host are injected
How can people gain acquired immunity
Naturally acquired immunity:
Passive - baby gets antibodies from mother through placenta and milk
Active - person gets into direct contact with pathogen and immune system produces antibodies
Artificially acquired immunity:
Passive - antibodies of another host injected
Active - weakened form of the apogee are injected
How do antibiotics work
Destroy bacteria in 1 of 3 ways:
1. Weaken cell wall and cause bacterium to burst
2. Damage cell membrane and contents leak out
3. Inhibit metabolism of the bacteria
How does resistance to bacteria happen
Random mutations of bacteria occurs and some bacteria are more resistant to antibiotics than others
If course of antibiotics isn’t complete, weaker bacteria are killed but more resistant bacteria survive
More resistant bacteria continues breeding
Why does resistance to bacteria happen
- Not completing course of antibiotics
- Incorrect antibiotics prescribed
- Antibiotics prescribed for viral infections
- Unnecessary use of antibiotics
