MICRO ORGANISMS

LEARNING INTENTIONS

• Basic structure and characteristics of viruses, bacteria,

protists and fungi

• Their roles in maintaining balance in the environment and

web of life

• Symbiotic relationships between nitrogen-fixing bacteria

and plants, and Escherichia coli in the human intestine

• The effects and management of diseases caused by

micro-organism

• The use of drugs such as antibiotics on micro-organisms

PROPERTIES OF LIFE

1. Cellular respiration

2. Reproduction

3. Nutrition

4. Excretion

5. Locomotion and movement

6. Sensitivity and responsiveness

7. Growth and development

BIODIVERSITY OF MICRO-ORGANISMS

• Living organisms occur in different

shapes and sizes

• Scientists have found it convenient

to classify all these organism in to

the following kingdoms

A. Monera

B. Protista

C. Fungi

D. Plantae

E. Animalia

MICRO-ORGANISMS: ARE SO SMALL THAT THEY

CANNOT BE SEEN WITHOUT USING A MICROSCOPE

• Micro-organisms are found in all five

kingdoms (both good and bad)

• Micro-organisms are also found in a sixth

group which cannot be placed in any of the

five kingdoms. These micro-organisms are

called viruses

• Note that all the organisms in any kingdom

are not identical in structure or the way in

which they live

VIRUSES

• Cannot be placed in any of the five

kingdoms of living organism, because

they show characteristics of both non-

living things as well as some

characteristics of living organism.

• Can you remember the properties of

life?

PROPERTIES OF LIFE

1. Cellular respiration

2. Reproduction

3. Nutrition

4. Excretion

5. Locomotion and movement

6. Sensitivity and responsiveness

7. Growth and development

BASIC STRUCTURE OF VIRUSES

• Viruses come in different shapes and

sizes, but have the same basic structure.

• They are very small.

• A virus consists of a central core of nucleic

acid (DNA or RNA) covered by a protein

coat (capsid)

• Viruses that attack bacteria and plants

contain RNA only

• Those that attack animals may have either

DNA or RNA

• They are considered to be non-cellular or

acellular

HIV

Influenza virus

CHARACTERISTICS OF VIRUSES

• Viruses are parasites living in plants,

animals or bacteria (inactive in water,

air, soil)

• They are very specific with regard to

their host

• Viruses are extremely small

• Viruses are pathogens because they

need the host cell to replicate

• They have the ability to assemble

themselves within the host cell

DIAGRAM

VIRUSES – MAINTAINING A HEALTHY ENVIRONMENT

• CONTROL MANY ECOLOGICAL PROCESSES SUCH AS NUTRIENT CYCLING,

BACTERIAL AND ALGAL BIODIVERSITY AND ALGAL BLOOM CONTROL

• SCIENTISTS HAVE RECENTLY DISCOVERED THAT THERE ARE MANY VIRUSES

FOUND IN THE OCEAN. WHEN SEA-ORGANISMS DIE FROM A VIRAL

INFECTION THEIR BODIES PROVIDE NUTRIENTS TO BACTERIA IN THE DEEPER

PARTS OF THE OCEAN

• VIRUSES ARE PATHOGENS AND CAUSE MANY DISEASES IN PLANTS, ANIMALS

AND HUMANS.

• DISEASE HELP CONTROL THE NUMBERS OF DOMINANT HOST SPECIES

DISEASESEFFECT AND MANAGEMENT OF DISEASES CAUSED BY

VIRUSES

RABIES

• CAUSED BY THE RABIES VIRUS

• PRESENT ON EVERY CONTINENT EXCEPT AUSTRALIA AND

ANTARCTICA

• ONCE SYMPTOMS DEVELOP RABIES IS FATAL

• SPREADS THROUGH THE CENTRAL NERVOUS SYSTEM AND CAUSES

FATAL INFLAMMATION OF THE BRAIN AND SPINAL CORD

• TWO TYPES: FURIOUS AND PARALYTIC

RABIES VIRUS: CAUSED BY A VIRUS WHICH ATTACKS

DOMESTIC AND WILD ANIMALS, IT IS TRANSMITTED TO HUMANS BY A BITE OF AN INFECTED ANIMAL (SALIVA)

EFFECTS ON HUMANS

• AN INCUBATION PERIOD OF 1 TO 60 DAYS MAY OCCUR

• ONSET OF THE ILLNESS MAY OCCUR AFTER THE INCUBATION

PERIOD. SYMPTOMS THAT MAY OCCUR INCLUDE HEADACHES,

FEVER, SORE THROAT, NAUSEA, DIARRHOEA AND FATIGUE.

• DURING THE ACUTE NEUROLOGICAL OR AGITATION PHASE, THE

INFECTED PERSON MAY RUN ABOUT, UNDERGO CONVULSIVE

SEIZURES, PRODUCE LARGE AMOUNTS OF SALIVA, SHOW A FEAR

OF WATER AND HAVE A DIFFICULTY IN SWALLOWING AND

BREATHING.

• DEATH MAY OCCUR DUE TO HEART FAILURE AND BREATHING

DIFFICULTIES OR SEIZURES.

VACCINATIONS

• PREVENTION IS BETTER THAN CURE: VACCINATE ANIMALS

• PEOPLE WHO WORK WITH ANIMALS SHOULD BE IMMUNIZED BY

TAKING A VACCINE AGAINST THE RABIES VIRUS

• THEY SHOULD ALSO WEAR PROTECTIVE CLOTHING WHEN

WORKING WITH ANIMALS

TREATMENT ON EXPOSURE

• PERSONS EXPOSED TO THE RABIES VIRUS BY BEING BITTEN OR SCRATCHED

BY A RABID ANIMAL SHOULD BE TREATED IMMEDIATELY BY A QUALIFIED

MEDICAL PRACTITIONER.

• BY WASHING THE WOUND THOROUGHLY AND A COURSE OF

VACCINATION

• ONCE A PERSON SHOWS SIGNS OF THE DISEASE, THERE IS NO EFFECTIVE

TREATMENT.

OTHER RABIES SLIDES

HIV / AIDS (VIRUS)

• HIV (HUMAN IMMUNODEFICIENCY VIRUS) CAUSES AIDS (ACQUIRED

IMMUNE DEFICIENCY SYNDROME)

• IT IS A VIRAL DISEASE THAT ATTACKS THE BODY’S IMMUNE SYSTEM

• PATIENTS INFECTED WITH HIV DO NOT HAVE RESISTANCE TO

INFECTIONS AND CAN EASILY DIE FROM INFECTIONS OR MILD

DISEASES

• BODY FLUIDS SUCH AS BLOOD, SEMEN AND VAGINAL FLUID TRANSFER

HIV FROM ONE PERSON TO THE NEXT, INFECTED NEEDLES, BLOOD

TRANSFUSIONS, PREGNANCY AND CHILD BIRTH ARE ALSO WAYS HIV

CAN SPREAD AMONGST PEOPLE

• SYMPTOMS OF THE DISEASE DO NOT NECESSARILY DEVELOP 5 – 7

YEARS AFTER THE PERSON 1ST GOT INFECTED.

• HOWEVER PEOPLE ARE INFECTIOUS FROM THE MOMENT THEY GET

HIV

• HIV IS A RNA RETROVIRUS

• SIGNS AND SYMPTOMS

• ABOUT 50% OF PEOPLE INFECTED WITH HIV WILL SHOW FLU-LIKE

SYMPTOMS AROUND 6 WEEKS AFTER INFECTION

• THE REST HAVE NO SYMPTOMS

• ONSET OF AIDS OCCURS ONCE THE IMMUNE SYSTEM IS NO LONGER

ABLE TO FIGHT OFF INFECTIONS

• COMMON OPPORTUNISTIC INFECTIONS INCLUDE TB, ORAL THRUSH,

MENINGITIS, CHRONIC DIARRHOEA AND WASTING

• EFFECTS OF HIV / AIDS ON THE BODY

• HIV DAMAGES THE BODY’S IMMUNE SYSTEM

• IN HEALTHY PEOPLE SPECIAL WHITE BLOOD CELLS CALLED T4 CELLS (LYMPHOCYTES)

START FIGHTING AGAINST ANY VIRUS OR BACTERIUM THAT INVADES THE BODY

• IN PEOPLE INFECTED WITH HIV THE VIRUS ATTACKS THE T4 CELLS THE BODY CANNOT

PROTECT ITSELF AGAINST BACTERIA AND VIRUSES AND THE PATIENT IS EXPOSED TO

OPPORTUNISTIC INFECTIONS

• HIV RECOGNISES T4 CELLS BECAUSE THE PROTEINS ON THE SURFACE OF THE HIV FIT

EXACTLY INTO THE PROTEIN ON THE SURFACE OF CD4T CELLS.

• HIV SLOWLY DAMAGES THE IMMUNE SYSTEM FOR MANY YEARS AFTER IT HAS

INFECTED THE BODY.

• ONCE THE IMMUNE SYSTEM IS DAMAGED PEOPLE GET MILD SYMPTOMS SUCH AS

SKIN RASHES, FATIGUE, WEIGHT LOSS, NIGHT SWEATS AND ORAL THRUSH

• AFTER THAT MORE SEVERE SYMPTOMS START OCCURRING SUCH AS PNEUMONIA AS

THE PERSONS IMMUNE SYSTEM IS NO LONGER ABLE TO FIGHT INFECTIONS.

• (WHEN YOUR CD4T COUNT GETS BELOW A CERTAIN POINT YOU ARE CLASSIFIED AS

HAVING AIDS AND NO LONGER HIV)

• MANAGEMENT OF HIV/AIDS

• YOU CAN GET AN HIV TEST FROM ANY PUBLIC CLINIC OR DOCTORS

SURGERY

• IF YOU GET A NEGATIVE RESULT IN THE FIRST SIX MONTHS, YOU

SHOULD PERHAPS GO FOR A SECOND TEST

• SHOULD YOU HAVE A POSITIVE RESULT A TRAINED COUNSELLOR WILL

GIVE YOU THE RESULT FOR EMOTIONAL SUPPORT AND TO EXPLAIN

THE PROCEDURES REQUIRED FROM HERE ON

• ANTIRETROVIRAL’S ARE MEDICINES THAT DOCTORS GIVE OUT TO

PREVENT THE VIRUS FROM REPLICATING. IN SA GIVE IT AS A

COMBINATION OF THREE DIFFERENT DRUGS: ZIDOVUDINE,

LAMIVUDINE AND NEVIRAPINE.

• EACH DRUG WORKS ON A DIFFERENT STEP OF THE HIV CYCLE.

• THE TREATMENT MUST BE TAKEN STRICTLY AS PRESCRIBED FOR THE

REST OF THE PERSONS LIFE

• THEY DO NOT CURE HIV BUT OFFER MANY BENEFITS

• MANAGEMENT OF HIV/AIDS

• AVOID CONTACT WITH CONTAMINATED BODY FLUIDS

• HIV-PREGNANT WOMEN RECEIVE ANTIRETROVIRAL DRUGS TO

PREVENT TRANSMISSION TO THEIR UNBORN CHILD

• ONCE INFECTED TRY TO STAY AS HEALTHY AS POSSIBLE FOR AS LONG

AS POSSIBLE

• PROPHYLAXIS MAY BE OFFERED AGAINST TB AND OPPORTUNISTIC

INFECTIONS

• ANTIRETROVIRAL DRUGS DO NOT KILL THE VIRUS BUT PREVENT

FURTHER DESTRUCTION OF THE IMMUNE SYSTEM

• CLASSROOM ACTIVITY 14 PAGE 44

• INTERPRET DATA ON HIV / AIDS

BACTERIA • Bacteria are about 50 times larger than

viruses, but they are still the smallest

known living organisms.

• Bacteria are found everywhere (air, soil

and water)

• Bacteria prefer moisture and darkness

• The majority grow and reproduce best

when the temperature is between 30 and

37˚C

• They can survive at extremes of

temperature from -18˚ to 70˚C

BASIC STRUCTURE OF BACTERIA

• A Bacterium is made of

only one cell (unicellular)

• Bacteria are regarded as

prokaryotic organisms

(why?)

• Four main shapes of

bacteria occur coccus

(spherical cells), bacillus

(rod-like cells), spirillum

(spiral cells and vibrio

(comma-shaped cells)

BACTERIAL CELL (IRRESPECTIVE OF ITS SHAPE IT HAS THE FOLLOWING STRUCTURES)

• A cell wall (made up of peptidoglycan,

polysaccharides, proteins and lipids) occurs on

the outside

• Many bacteria cells also have a slime capsule

which protects the bacterium from drying out.

• Many bacteria also have whip-like flagella by

means of which they move in liquid

• Cytoplasm occurs within the cell wall

• No nucleus but chromatin network (nucleoid)

• Ribosomes occur within the cytoplasm, but there

are no mitochondria, plastids or endoplasmic

reticulum

BACTERIAL CELL (IRRESPECTIVE OF ITS SHAPE IT HAS THE FOLLOWING STRUCTURES)

• Fimbriae are involved in attachment

• Pili are involved in conjugation (transfer of DNA from one cell to

another)

• Cell membrane is a lipid bilayer (involved in many essential

processes)

CHARACTERISTICS OF BACTERIA

• Some bacteria are autotrophic

while others are heterotrophic

• There are two types of autotrophic

bacteria

A. Photosynthetic bacteria:

manufacture their own food using

light energy

B. Chemosynthetic bacteria:

manufacture their own food using

the energy released from

chemical processes

THERE ARE THREE TYPES OF HETEROTROPHIC BACTERIA

A. Parasitic bacteria: obtain food from

other living organisms on which they

live.

B. Saprotrophic bacteria: obtain food

from dead plant and animal material

C. Mutualistic bacteria: live in or on plants

and animals for the benefit of both

organisms

DIAGRAM

• HOMEWORK

BACTERIA

• BACTERIA PLAY AN IMPORTANT ROLE IN LIFE AND ARE INVOLVED IN

SYMBIOTIC RELATIONSHIPS

1. MUTUALISM: NITROGEN-FIXING BACTERIA USE NITROGEN FROM THE AIR

TO FORM AMMONIA. THESE BACTERIA LIVE IN ROOTS OF LEGUMINOUS

PLANTS. THE BACTERIA CONVERT THE AMMONIA INTO NITRATES. PLANTS

ABSORB THE NITRATES AND USE THEM IN METABOLIC PROCESSES.

BACTERIA HAS A PLACE TO LIVE AND PLANTS GET NUTRIENTS

BACTERIA

1. MUTUALISM: E. COLI IN THE LARGE INTESTINES IN HUMANS. THE BACTERIA

HAS A GOOD SUPPLY OF FOOD AND A GROWTH HABITAT, THE BACTERIA

PROVIDE HUMANS WITH VIT K WHICH ASSISTS IN THE ABSORPTION OF

NUTRIENTS

2. COMMENSALISM: THE BACTERIUM STAPHYLOCOCCUS EPIDERMIDIS IS

PRESENT ON HUMAN SKIN. THE BACTERIUM BENEFITS FROM HAVING A

HABITAT BUT IT DOES NOT HARM OUR SKIN

BACTERIA CONTINUED…

CONTINUED AGAIN…

• BACTERIA IN BIOTECHNOLOGY

• WE USE CERTAIN BACTERIA TO MAKE CERTAIN ANTIBIOTICS

• SOME SPECIES OF BACTERIA ARE ABLE TO DECOMPOSE SEWAGE WASTE

• CERTAIN SPECIES OF BACTERIA CAN DIGEST HYDROCARBONS IN PETROLEUM,

ENVIRONMENTALISTS USE THESE BACTERIA TO CLEAN UP OIL SPILLS

• SCIENTISTS USE BACTERIA AS BIOLOGICAL PEST CONTROL

• DAIRY FARMERS USE CERTAIN BACTERIA TO MAKE CHEESE AND YOGHURT,

CERTAIN INDUSTRIES ALSO USE BACTERIA TO MAKE VINEGAR

CHOLERA

• CAUSED BY THE BACTERIUM VIBRIO CHOLERAE WHEN WATER OR

FOOD CONTAMINATED BY FAECES IS SWALLOWED.

• IT AFFECTS THE ALIMENTARY CANAL, CAUSING SEVERE DIARRHOEA..

• IT IS LINKED TO INSUFFICIENT ACCESS TO SAFE WATER AND PROPER

SANITATION.

SYMPTOMS OF CHOLERA

• PROFUSE WATERY DIARRHOEA AND VOMITING

• DEHYDRATION AND LOSS OF ELECTROLYTES

• SYMPTOMS APPEAR 1-5 DAYS AFTER BEING INFECTED

• CAN LOSE 10-20L OF WATER A DAY AND CAN DIE OF

DEHYDRATION WITHIN HOURS OF SYMPTOMS STARTING

• THERE ARE ALSO DISEASE CARRIERS

EFFECTS OF CHOLERA

• ABOUT 75% OF PEOPLE INFECTED WITH CHOLERA DO NOT DEVELOP

ANY SYMPTOMS.

• THE PATHOGENIC BACTERIA STAY IN THEIR FAECES FOR 7 TO 14 DAYS

• ABOUT 25% OF PEOPLE INFECTED SHOW A SUDDEN ONSET OF ACUTE

WATERY DIARRHOEA THAT CAN LEAD TO DEATH BY SEVERE

DEHYDRATION.

• INDIVIDUALS WITH LOWER IMMUNITY, SUCH AS MALNOURISHED

CHILDREN OR PEOPLE LIVING WITH HIV, ARE AT GREATER RISK OF

DEATH IF INFECTED BY CHOLERA.

• IT IS SUCH A VIRULENT DISEASE THAT, IF LEFT UNTREATED, IT CAN EVEN

KILL HEALTHY ADULTS WITHIN A FEW HOURS.

MANAGEMENT OF CHOLERA

PREVENTION

• HEALTH EDUCATION, INCLUDING THE NEED TO WASH HANDS WITH SOAP AFTER DEFAECATION AND BEFORE

HANDLING FOOD.

• CLEAN WATER AND PROPER SANITATION FOR ALL SECTORS OF THE POPULATION IS EXTREMELY IMPORTANT.

• SEWAGE TREATMENT

TREATMENT

• ABOUT 80% OF PATIENTS CAN BE SUCCESSFULLY TREATED BY DRINKING A SOLUTION OF RE-HYDRATION SALTS

• IN VERY SERE CASES, LIQUIDS WITH RE-HYDRATION SALTS MAY HAVE TO BE GIVEN BY MEANS OF ‘DRIPS’.

• SOMETIMES, ANTIBIOTICS MAY BE GIVEN TO STOP DIARRHOEA.

TUBERCULOSIS (BACTERIA)

• TB IS AN INFECTIOUS DISEASE CAUSED BY THE BACTERIUM

MYCOBACTERIUM TUBERCULOSIS.

• TB CAUSES ABOUT 4-8 MILLION DEATHS EACH YEAR WORLD WIDE

• THE EFFECTS OF TB ON THE BODY

TB USUALLY AFFECTS THE LUNGS WHERE IT CAN EITHER BE DORMANT OR GROW

AND REPRODUCE. HOWEVER IT CAN AFFECT ALMOST ANY PART OF THE BODY. AT

FIRST THE PATIENTS MAY NOT EVEN NOTICE THE SYMPTOMS.

THE BACTERIA USUALLY GROW IN THE LUNGS, DESTROYING THE LUNG TISSUE.

THE SYMPTOMS INCLUDE:

1. A PERSISTENT COUGH THAT USUALLY LASTS MORE THAN 3 WEEKS

2. NIGHT SWEATS FOR WEEKS OR MONTHS

3. WEIGHT LOSS

4. FATIGUE

5. HIGH TEMPERATURE

6. SHORTNESS OF BREATH

7. BLOOD WHEN COUGHING

• MANAGEMENT OF TB

THERE ARE METHODS FOR TREATING TB AND PREVENT GETTING TB. THESE

METHODS ARE:

1. VACCINATIONS

• CAN PROVIDE US WITH ACTIVE AND PASSIVE COMMUNITY WHICH MAKES US

IMMUNE TO THE DISEASE

• DOCTORS GIVE 6 WEEK OLD BABIES THE BCG VACCINATION TO TRY TO

PREVENT INFECTION BY TB BACTERIA

2. ANTIBIOTICS

• A PERSON INFECTED CAN TAKE AN ANTIBIOTIC-COCKTAIL WHICH IS MADE UP

OF THREE ANTIBIOTICS.

• PATIENTS MUST TAKE THESE ANTIBIOTICS FOR 6 MONTHS. IF THEY D O NOT

TAKE ALL THEIR MEDICINES, THE BACTERIA CAN MATURE QUICKLY AND BECOME

RESISTANT TO THE ANTIBIOTICS. RECENTLY IN SA A NEW ANTIBIOTIC-RESISTANT

STRAIN IF TB CALLED XDR TB (EXTENSIVELY DRUG RESISTANT TUBERCULOSIS)

DEVELOPED. THIS HAPPENS AS A RESULT OF PATIENTS NOT COMPLETING THEIR

TREATMENT

• THE TREATMENT HAS MANY UNPLEASANT SIDE-EFFECTS

-

PROTISTA

• Protists consist of three main groups

1. Animal-like protists

2. Plant-like protists

3. Algae

• Protists are all eukaryotes

• They are micro-organisms that are

simple in structure

• Most are unicellular although some are

multicellular with no specialised tissues

• They range from microscopic organisms

to huge tree-like structures.

DIAGRAMS

PROTISTS

• FORM THE BASIS OF MANY FOOD CHAINS

• ENVIRONMENTAL ROLE

• GREEN ALGAE CAN PHOTOSYNTHESIZE AND PRODUCE OXYGEN – AQUATICS

USE THIS OXYGEN TO SURVIVE

• PHYTOPLANKTON CONSIST OF ALGAE AND DIATOM SPECIES. THEY FORM THE

BASIS OF THE FOOD CHAIN IN AQUATIC ENVIRONMENTS. THEY

PHOTOSYNTHESIZE AND PRODUCE CARBOHYDRATES. AQUATIC ORGANISMS

USE THESE CARBOHYDRATES AS A FOOD SOURCE

• SOME PROTISTA ARE PREDATORS (EG: AMOEBA) SO THEY ARE IMPORTANT

PRIMARY CONSUMERS IN THE FOOD CHAIN.

• FOOD: SEAWEEDS – BEEN EATEN BY HUMANS FOR YEARS

PROTISTA CONTINUED…• FERTILIZERS

• INDUSTRY

• MEDICINES

• DISEASES

• SOME PARASITIC PROTISTS ARE PATHOGENS SUCH AS

• TRYPANASOMA GAMBIENS CAUSES AFRICAN SLEEPING SICKNESS

• PLASMODIUM VIVAX AND PLASMODIUM FALCIPARUM WHICH CAUSES MALARIA

• MANY OF THESE PATHOGENS HAVE A BIG ECOLOGICAL IMPACT WHEN THEY

CAUSE THE DEATH OF ANIMALS

MALARIA (PROTISTS)

• PLASMODIUM IS THE MALARIA PARASITE

• IT IS A PROTISTA THAT LIVES IN THE BLOOD STREAM AND LIVER OF

HUMANS INFECTED BY THE PARASITE.

• THE FEMALE ANOPHELES MOSQUITO IS THE DISEASE VECTOR. THE

MOSQUITO TRANSMITS THE MALARIA PARASITE BY SUCKING BLOOD

FROM HUMANS

• UNTIL 1999 IT WAS LISTED AS THE DISEASE THAT KILLS THE MOST

PEOPLE PER ANNUM (HIV / AIDS HAS TAKEN OVER)

• EACH YEAR BETWEEN 300 AND 500 MILLION CASES OF MALARIA ARE

REPORTED WORLD WIDE. BETWEEN 1.5 AND 2.7 MILLION PEOPLE DIE

FROM MALARIA EACH YEAR.

• MALARIA DISTRIBUTION IN THE WORLD

• EFFECTS OF MALARIA

THE INFECTED PERSON FEELS SYMPTOMS OF THE DISEASE WHEN THE

PLASMODIUM PARASITE LEAVES THE LIVER AND ENTERS THE RED

BLOOD CELLS.

WHEN THE RED BLOOD CELL BURST, THE PATIENTS TEMPERATURE

INCREASES AND CAN GO AS HIGH AS 40˚C.

DEVELOP FLU-LIKE SYMPTOMS

THIS STAGE OF THE DISEASE CAN BE VERY DANGEROUS AND MANY

PEOPLE DIE.

THE BURST BLOOD CELLS CAN BLOCK BLOOD VESSELS AND STOP

OXYGEN REACHING MANY PARTS OF THE BODY

• MANAGEMENT OF MALARIA

MALARIA IS A COMMUNITY DISEASE THAT AFFECTS A LARGE NUMBER OF PEOPLE

WE NEED A COMBINATION OF STRATEGIES TO TRY AND CONTROL THE DISEASE

MOST OF THE STRATEGIES ARE AIMED AT THE MOSQUITO EG.

o PREVENT THE MOSQUITO FROM BREEDING (NEED WATER TO LAY THEIR EGGS –

SPRAY LAKES WITH THIN LAYER OF OIL / INSECTICIDES)

o PREVENT MOSQUITO FROM BITING PEOPLE – MOSQUITO NETS AND FLY SCREENS

o USE MEDICINES TO KILL THE MALARIA PARASITE IN BLOOD STREAM AND LIVER

o TAKE PROPHYLACTIC MEDICATION TO PREVENT GETTING INFECTED.

PEOPLE CANNOT BE IMMUNIZED AGAINST MALARIA – SCIENTISTS ARE WORKING

AT FINDING A WAY

DDT IS A PESTICIDE THAT IS USED TO KILL THE INSECT BUT IT IS BAD FOR THE

ECOSYSTEM SO IT IS NO LONGER USED.

FUNGI

• Mushrooms, yeast, ringworms and the

moulds found on bread and fruit are

all examples of fungi.

• Fungi are divided into two groups:

unicellular and multicellular

• Did you know that the greenish mould

Penicillium notatum from which the

antibiotic penicillin is obtained, is also

a fungus?

BASIC STRUCTURE OF FUNGI

• Fungi have a unique cell wall structure

made up of chitin.

• All fungi do not have chlorophyll

• All fungi reproduce by means of spores

• Fungi are all eukaryotic

• Most fungi are filamentous (hyphae).

• Fungi reproduce both sexually and

asexually

• Although all fungi reproduce by spores,

fungi are not all the same in terms of

where these spores are produced. For

example

a. Bread mould produce their spores in

special spore cases called sporangia

b. Others e.g. Mushrooms produce their

spores in club-shaped structures which

are usually found within cap-like

fruiting bodies

c. Still others, produce spores in sac-like

structures e.g. Yeast and penicillium• CLASSROOM ACTIVITY 3

FUNGAL DISEASES AND DIAGRAM

FUNGI

• FUNGI ARE DECOMPOSERS AND RECYCLE NUTRIENTS

• FUNGI ARE IMPORTANT TO PEOPLE AS A SOURCE OF FOOD AND MEDICINE

• MUSHROOMS

• PENICILLIUM FUNGUS FOR THE ANTIBIOTIC PENICILLIN

• SYMBIOTIC RELATIONSHIPS

• MUTUALISM: LICHENS + MYCORRHIZA

• PARASITIC: CANDIDA ALBICANS – BENEFICIAL IN SMALL AMOUNTS BUT BAD IN

LARGE AMOUNTS

ATHLETES FOOT (FUNGI)

• ATHLETES FOOT IS A SKIN INFECTION CAUSED BY THE MICROSCOPIC TINEA

FUNGUS.

• PEOPLE OFTEN GET THE FUNGUS WALKING BAREFOOT IN PUBLIC SHOWERS

• GROW WITHIN THE DEAD LAYERS OF THE SKIN

• PEOPLE WHO ARE INFECTED WITH THE FUNGUS LEAVE SMALL PIECES OF THE

FUNGUS WHEN THEY WALK

• THE FUNGUS GROWS BETWEEN THE TOES AND CAUSES RED SCALY PATCHES

ON THE SKIN THAT ARE VERY ITCHY

• GOOD FOOT HYGIENE IS IMPORTANT – MAKE SURE SHOES ARE BIG ENOUGH,

CHANGE SOCKS EVERYDAY, WASH YOUR FEET REGULARLY WITH SOAP AND

WATER, AND DRY WELL.

• MAKE SURE PUBLIC SHOWERS ARE WASHED REGULARLY WITH DISINFECTANT

• RINGWORM

ATHLETE’S FOOT

ATHLETE’S FOOT

PLANT RUST (FUNGI)

• PLANT RUST ARE FUNGAL PARASITES THAT CAN DAMAGE A LARGE

NUMBER OF CROPS EG. PUCCINIA GRAMINIS INFECTS WHEAT

• THEY ALSO MAKE HOST PLANTS VULNERABLE TO OTHER DISEASES

• FARMERS CAN USE FUNGICIDE TO PREVENT FUNGAL INFECTIONS

OR TO CURE INFECTED PLANTS

• IF NOT TREATED THE PLANTS WILL DIE.

• RUSTS PRODUCE MILLIONS OF TINY SPORES

MANAGING RUSTS

• ROTATING CROPS TO STOP THE SPREAD OF THE DISEASE

• USING RUST-RESISTANT VARIETIES OF CROPS AND “DISEASE-FREE” SEEDS

• ALL EQUIPMENT SHOULD BE STERILISED

• NOT EXPOSING CROPS TO MOIST HUMID CONDITIONS FOR LONG PERIODS.

• BURNING INFECTED MATERIAL