This document discusses different types of microbes including viruses, bacteria, protists, and fungi. It provides descriptions of their characteristics and structures. Viruses are described as obligate intracellular parasites that can only replicate within host cells. They are not considered living due to their inability to carry out certain functions. Bacteria are unicellular prokaryotes that can reproduce through binary fission. Protists exhibit a wide diversity and include protozoa and algae. Fungi consist of multicellular mushrooms and molds as well as unicellular yeast. Many microbes are pathogens that can cause infectious diseases in humans and animals.

1. VIRUSES, BACTERIA, PROTISTS
AND FUNGI
MODULE 2: LIFE AT MOLECULAR,
CELLULAR AND TISSUE LEVEL

2. MICROBES/MICRO ORGANISMS
• Some organisms are so small, that it can’t be seen with
the naked eye
• This group includes:
• VIRUSES: Smaller than a cell and does not form part of
the 5 Kingdom system that classifies living organisms
• BACTERIA: unicellular procariotic organisms
• PROTISTS: unicellular protosoa with animal-like
characteristics as well as algae with plant-like
characteristics
• FUNGI: includes mushrooms, unicellular yeast cells and
fungi that consist of thread-like filaments

4. •A Disease causing
organism

6. • They contain either DNA or RNA but never both.
• They are OBLIGATE INTRA-CELLULAR PARASITES –
can only replicate within a living host cell
• Virusses are host or tissue specific
• They are PATHOGENS (disease causing
organisms)
• Virusses REPRODUCE by changing the genetic
material of the host cell to its own

7. WHY ARE VIRUSSES REGARDED AS NON-LIVING?
• They can’t feed
• They can’t respire
• They can’t reproduce, only multiply
• They can’t excrete
• They show no form of locomotion
• They show no sensitivity
• They can’t grow

8. • They have no nucleus
• They have no cytoplasm
• They have no organelles

9. VIRUSES ARE ROD SHAPED OR SPHERICAL
• Some viruses that
attack bavteria are
more complex in
structure:
• Spherical head
• Rod-shaped
• Known as a
BACTERIOPHAGE

10. REPRODUCTION OF VIRUSES
1. The virus approaches a cell
2. Virus attaches to receptor on cell membrane of host
cell
3. Virus engulfed by endocytosis
4. Virus wall disintegrates
5. Virus releases its nucleic acid
6. A new virus nucleic acid is formed from nucleic acid of
host cell
7. New virus with protein shield is formed
8. Host cell burts open and new viruses are released
9. Host cell destroyed in the process

11. 1. Virus
approaches the
host cell
2. The virus
attaches itself
to the host cell 3. The virus
releases its nucleic
acid
4. Virus uses the host cell’s
nucleic acid to replicate its
own
5. New protein shields
(capsids) are formed around
nucleic acids
6. New viruses are
released as host cells
burst open and is
destroyed

12. MONERA e.g. BACTERIA
• GENERAL CHARACTERISTICS:
1. Unicellular and simple organisms
2. Contain no true nucleus – thus PROKARYOTIC
3. Some are AUTOTROPHIC (produce own food by
means of photosynthesis and chemosynthesis)
4. Most are HETEROTROPHIC and can’s produce
their own food.
5. Heterotrophic bacteria are either parasitic or
saprophytes or live mutualistic with other
organisms

14. REPRODUCTION IN BACTERIA
• ASEXUALLY through BINARY FISSION:
• Single cell divide in TWO cells with identical DNA
composition
• As soon as conditions become UNFAVOURABLE,
some bacteria form ENDOSPORES that can
withstand extreme temperatures and drought.
• Develop a hard outer shell/wall and as soon as
conditions become favourable again, the
endospore burst open and become active again

15. DISEASE CAUSING BACTERIA
• PATHOGEN – an organism that causes disease
• Some bacteria cause disease and are
pathogenic
• Cause diseases such as cholera, tuberculosis
and anthrax (p.96 Focus on Life Sciences)

16. • Decompose dead plant and animal matter –
decompose sewage at purification plants
• Play role in nitrogen cycle
• Economic uses: production of yoghurt, cheese,
vinegar, gherkins, etc.
• Production of Pharmaceutical substances such as
antibiotics (together with moulds) vaccines and
steroids
• Used in biotechnology, such as the production of
human insulin

17. • KINGDOM: PROTISTA
• The kingdom with the LARGEST DIVERSITY
( more than 200 000 species)
• PROTOZOA – animal-like, unicellular
heterotrophic organisms
• ALGAE – plant-like, autotrophic organisms
• FUNGUS-SLIME + WATER SLIME – fungus-like
organisms

18. GENERAL CHARACTERISTICS:PROTISTS
• Some are unicellular and microscopic small;
others are multicellular and can be seen with
the naked eye
• Eukaryotic: contain a true nucleus
• Algae are autotrophic; and others are
heterotrophic
• Reproduction mainly asexually by binary
fission; some algae reproduce sexually
• Occur everywhere where there is water
• Some are PATHOGENIC and cause disease e.g.
Malaria and Sleeping sickness

19. STRUCTURE OF PROTISTS
• E.g. The Amoeba proteus

20. Structure of Amoeba
• Unicellular with irregular shape (shape
changes as it moves or take food in)
• Body consists of cytoplasm and nucleus
• Cytoplasm consists of:
• (i) ectoplasm: clear, jelly-like section on the
outside
• (ii) endoplasm: grey, liquid part on the
inside
• Outer membrane is plasma membrane

21. Important terms and parts
• Food vacuole: in which food is digested
• Contractile vacuole: responsible for
osmoregulation (control water balance)
• Nucleus: control all cell activities
• Pseudopodia (false feet): ectoplasm
forms protrusions anywhere and is
temporary

23. • Yeasts are unicellular; mushrooms and moulds
are multicellular
• Eukaryotes: contain true nucleus
• Contain no chlorophyl and are HETEROTROPHIC
• Most fungi are SAPROPHYTES (live on dead,
organic matter)
• Sommige is PARASIETE – teer op lewende
materiaal
• Sommige is MUTUALISTIES- leef SAAM met ander
organismes

24. More characteristics….
• Most fungi are USEFULL e.g.
• (i) decompose dead organic matter (together
with bacteria)
• (ii) are used in production of antibiotic
• (iii) yeasts are used for baking of bread and
production of alcoholic drinks

25. Other fungi are PATHOGENIC…
• cause diseases such as:
• Rust in Corn
• Athlete’s foot
• Thrush in humans

26. Structure of Fungi e.g. Bread mould

27. • Rhizopus is multicellular and consists of
branched filaments, the hyphae
• The hyphae are interwoven to form the
vegetative body, the mycelium
• Rhizopus is a THALLUS – no true roots, stems
and leaves are distinguished.

28. THREE TYPES OF HYPHAE
• 3 TYPES hyphae:
• (a) STOLONS: the hyphae that branch over the
surface of the substrate
• (b) RHIZOIDS: the hyphae that penetrate the
substrate (bread) and anchor the mycelium
SPORANGIOPHORE: the hyphae that grow up
straight and that carry the sporangia

29. • The hyphae are branched
• Hyphae contain NO cross walls – in other
words, they are ASEPTATE
• A large amount of nuclei occur in
cytoplasm
• NB: Many other fungi’s hyphae contain
cross walls (septate)

30. • Source of food, e.g. mushrooms
• Yeast cells responsible for fermentation
process in the production of alcoholic drinks
(e.g. Wine and beer), yoghurt and the baking
of bread
• Certain fungi play role in production of cheese
• Is used in production of antibiotic e.g.
Penicillin obtained from the mould Penicillium
notatum

31. • Refers to knowledge obtained from communities
or cultures over generations through their
interactions with their environment
• Indigenous knowledge forms the basis for
decisions in agriculture, health care, food
preparation, education and management of
resources
• BIOTECHNOLOGY is the use of living organisms in
industrial processes (food processing, production
of antibiotic and genetic manipulation of
agricultural crops

32. • Include ancient ways in which living
organisms (micro-organisms) were used to
make new products or to adapt existing
products.
• In South Africa, many indigenous black
populations use their knowledge of
fermentation for the production of beer,
amasi en mahewu(mageu)

33. Ask around….
• Ask your Mum, Granny, Grandpa or any other
person for a recipe to make ginger beer or
pineapple beer. Write it down and paste it in
your workbook.
• Did you know? Traditional beer made from maize
meal/sorghum contain only 3% alcohol as a result
of the fermentation process.
• Fermentation: where bacteria, yeast or moulds
respire in the absence of oxygen and where
alcohol and carbon dioxide are formed

34. • PRODUCTION OF CHEESE
• Lactic acid bacteria is added to pasteurised milk and
fermentation takes place
• Milk sugar (lactose) is converted into lactic acid
• The pH is lowered and the protein in milk (casein) from
clots (coagulate)
• The enzyme (rennin) are added to form more clots
• Solid clots are called curds and the liquid part is called
whey
• The curd is separated from the whey and allowed to
age to form cheese

35. • The sugar in grape juice is fermentated by
yeast cells occurring on the surface of
grapes
• The sugar is converted into alcohol and
carbon dioxide
• Additionacan be added to accelerate the
fermentation process
• The fermented pulp is known as must
• The must is filtered to remove all seeds and
skin and placed in large vats/barrels to age

36. Making of bread
• Flour, water, yeast and little sugar are
combined to form a dough
• The carbon dioxide that is released, makes the
dough rise
• In case the dough is placed in a warm place,
the process takes place faster
• The alcohol that is formed, evaporates during
the baking process

37. Microbes can cause disease
The diseases and their severity caused by microbes depend on the type of microbe.
Some of these are listed below.
VIRUSES BACTERIA
Influenza (flu) Food poisoning
Mumps Sore throats
Chickenpox Tuberculosis (TB)
Smallpox Tetanus
Polio Cholera
Rabies Typhoid
German measles Whooping cough
FUNGI
fungal sinusitis
Athletes foot
Onychomycosis
Causes discoloured toe
nails
Candidiasis / Thrush
Viral
meningitis
Bacterial
meningitis

38. Research and summarize
• Research the following on AIDS:
• Causes of AIDS
• How AIDS is transmitted
• Effect of AIDS on the human body
• Effect on children and familiesct on the
economy of South Africa

39. Research and summarize
• Management of AIDS under the following:
• Testing
• Treatment
• Prevention
• ETHICS, BELIEFS AND ATTITUDES REGARDING
HIV/AIDS

40. TUBERCULOSIS - TB
• BACTERIAL DISEASE
• Caused by bacteria Myobacterium tuberculosis
• Affect mainly the lungs, but also any other organ
in the body
• SA is one of 22 countries with highest growth rate
in TB infections
• TB is a poverty related disease (people stay
together in dark rooms with no/poor ventilation)

41. HOW IS TB TRANSMITTED?
Mouth
Mond
Skin/Vel
Cuts/Oop
wonde
Nose/Neus
Ears/Ore
Eyes
Oë
Genitals
Geslags-
organe

42. The spreading of microbes and disease is known as Transmission.
How do microbes spread?
Dirty water can transmit many
diseases, for example, cholera which
can be transmitted by drinking the
water.
• Transmission in water
A cough or a sneeze can release millions
of microbes into the air which could then
infect somebody else.
• Transmission by air

43. • Transmission by animals
An animal, e.g. a mosquito
(which spreads the
MALARIA PARASITE) can
carry the microbe from one
place to another.
Many microbes can be exchanged from one
person to another by direct or indirect contact:
• Direct contact by hand.
• Indirect contact by walking on a wet floor
already contaminated by someone else who
has Athlete’s foot.
• Sexual contact.
• Transmission by contact

44. • Transmission by contact
There are other forms of indirect contact, the
transmission of microbes from mother to unborn child.
If the mother develops the HIV/aids infection, it
can be passed on to the unborn child through the
placenta.
Transmission through the Placenta
Transmission via Breastfeeding
A child can also pick up microbes from the
mother, via the milk, if the child is being
breastfed.

45. How do we stop microbes spreading disease
We can prevent the spread of disease by making sure that
good hygiene is used in key places such as bathrooms and
kitchens.
Chemicals called antibiotics can be
used to treat bacterial infections.
People can be immunised against
some diseases by the injection of a
vaccine.

46. The distinction between
TB Infection and TB Disease
TB Infection TB Disease (in the lungs)
M. tuberculosis in the body
Tuberculin skin test reaction usually positive
No symptoms Symptoms such as cough, fever, weight
loss
Chest x-ray usually normal Chest x-ray usually abnormal
Sputum smears and cultures
negative
Sputum smears and cultures usually
positive (unless HIV+)
Not infectious Often infectious before treatment
Not a case of TB A case of TB

47. Fighting disease

48. Fighting disease

49. Droplet Nuclei

50. The fate of droplets ….

52. “Guidelines for the Prevention of Transmission of TB in Health
Care Facilities in Resource-Limited Settings in the Era of
Expanding HIV Care and Treatment and Increasing Drug-Resistant
TB”

53. Life cycle of the
malaria
mosquito