04 Micro-organisms Flashcards
Why micro-organisms are called “micro”
- They are generally too small to be seen with a naked eye.
- You need a microscope to be able to see them.
Name two instruments that can be used to view very small objects
- A magnifying glass
- A microscope
Even though we can’t see them, how do we know microbes are around us all the time (without microscopes, what evidence is there for their existence?)
- They occasionally make us sick or get infections
- They make food decay
- Ferment foods e.g. cause bread to rise
The study of micro-organisms
Microbiology
Magnify
To make something appear larger than its actual size
An organism consisting of a single cell
Unicellular
An organism consisting of many cells
Multicellular
Types of micro-organism
- Virus
- Bacteria
- Fungi
- Protist
Microbe depicted:
Virus
The micro-organism depicted:
Bacterium
When a number of bacteria live together in a large group they form a …
colony
The type of microbe depicted:
A protist
(Amoeba sp.)
A characteristic of the Protista that makes them different from plants and animals.
They include many unicellular organisms.
The type of organism depicted:
Fungi
(bread mould)
An example unicellular fungi
Yeast
Example multicellular Fungi
- Mushrooms
- Bread mould
How Fungi feed
- They spread microscopic filaments called hyphae
- Hyphae secrete enzymes (chemicals) that digest the food
- The hyphae then absorb the digested food
Hyphae
The microscopic filaments/threads that make up the most of the fungus organism
How Fungi reproduce
Spores produced in a sporangium
Why viruses are considered non-living
- They do not carry out the essential life processes (nutrition, excretion, respiration etc)
- They can only reproduce inside a host cell
What makes bacteria cells different from plant and animal cells
- They are very small and simple
- They have no special structure (the nucleus) that houses the cells DNA
Some organisms that are included in the Protista
- Amoeba
- Algae
- Diatoms
- Paramecium
- Slime moulds
A micrograph
A photograph of an object that is viewed under a microscope (i.e. magnified)
TB
Tuberculosis
Cause of TB
- A bacterium
- Mycobacterium tuberculosis
- Spread through the air when an infected person coughs or sneezes
- Droplets from the infected person carry the bacteria into others
Symptoms of TB
- A persistent cough (>3 weeks)
- Coughing up blood
- Fever and night sweats
- Weight loss
Managing TB
- Doctors can test for it (e.g. X-ray of lungs)
- Treatment is with a long course of antibiotics (>6 months)
AIDS
Acquired immunodeficiency disease
Cause of AIDS
- A virus
- Human Immunodeficiency Virus (HIV)
- HIV infects the immune cells of the body destroying the immune system
Effects of HIV infection
- Initially the person has a fever and flu-like symptoms
- These then disappear for some time
- After some time (sometimes years) the person starts to develop infections that normally their immune system would be able to fight
- Eventually, the person is very ill with everyday infections and has AIDS
Treatment of HIV infection
- Leading a healthy lifestyle
- Taking ARVs (antiretroviral medication)
- (There is currently no cure)
Ways that HIV is transmitted
- Unprotected sexual contact
- Sharing hypodermic needles
- Contact with infected blood
- Transfer from mother to child (e.g. during birth and breastfeeding)
Prevention of HIV
- Avoiding activities that put you at risk of being infected
- Getting regularly tested for HIV
Diseases caused by drinking water contaminated with bacteria
Waterborne diseases
Examples of bacteria causing waterborne diseases
- Escherichia coli* - cramps and diarrhoea
- Vibrio cholerae* - Cholera
Escherichia coli
(E. coli)
- A bacterium that lives naturally in our large intestines and normally keeps us healthy.
- It digests certain foods and releases nutrients for us.
- If ingested it enters the stomach and small intestine and causes cramps and diarrhoea.
Cause of bacteria in the water we consume
Water bodies contaminated with faecal matter
Prevention of waterborne diseases
- Treating sewerage appropriately
- Treating and purifying drinking water e.g. boiling and filtration
- Washing fruit and vegetables with clean water
Some ways of preventing infection
- Wear gloves when dealing with body fluids such as blood
- Practice safe sex
- Cover your mouth when you cough or sneeze
- Wash your hands with soap and water
- Boil or treat water for consumption
- Don’t share personal items
- Wash fruit and vegetables carefully
- Keep food in the fridge or freezer to prevent microbe growth
Vaccines
- A medical preparation of weakened or dead disease-causing microbes
- This trains the immune system for dealing with that type of microbe
- This prevents a person from getting infected with this type of microbe
Vaccination
Receiving a vaccine in order to prevent infection from those specific diseases
Pasteurisation
- A process of heating food or a liquid to kill most microbes (including disease-causing microbes)
- This makes food safer for storing and consuming
The scientist credited with the process of pasteurisation
- Louis Pasteur
- A chemist and microbiologist
Uses of microbes by humans
To make many types of food
To make medicines
Example uses of microbes to make food
- Yeasts and bacteria to make bread
- Yeasts and bacteria to make wine and beer
- Bacteria and moulds to make cheeses
- Bacteria to make yoghurt
- Bacteria to make cocoa (i.e. chocolate)
- Bacteria to make kimchi and sauerkraut
Antibiotics
- Substances that are produced by certain fungi
- They can harm or kill bacteria e.g. penicillin
- These are manufactured into medicines for treating bacterial infections
