This lesson describes the overview of the simple elements of life: Virus, archaea, and bacteria

1. Introduction to virus, archaea,
bacteria and protists: Chapter 21
Dr. Biswadeep Das
InSciEd Out Co-ordinator (India),
Assistant Professor,
School of Biotechnology,
KIIT University,
Bhu baneswar, India

2. Learning Goals
• Characterization of virus, archaea, bacteria and
protists.
• List and compare/contrast types of
microorganisms.
• List and explain how microorganisms interact
with human biology.

3. Tree of life
• Domains are above the kingdom level.
– rRNA studies by Carl Woese
– domain model and prokaryotic diversity

4. Classification of Living Things
The three-domain system
Bacteria Archaea Eukarya
Eubacteria
Archae-
bacteria
Protista Plantae Animalia
The six-kingdom system
Fungi

6. Domains of Microorganisms
• Archea
• Viruses
• Bacteria
• Protists

7. Archaebacteria
Cell Type Prokaryote (unicellular)
Reproduction Asexual (binary fission)
Nutrition Autotroph or Heterotroph
Location Extreme Environments Volcanoes,
Deep Sea Vents, Yellowstone Hot
Springs
Examples Methanogens
Thermophiles

8. Black smokers in geothermal vents in deep ocean

9. Domains of Microorganisms
• Archea
• Viruses
• Bacteria
• Protists

10. Viruses
• A virus is a tiny non-living particle that invades
and then multiples inside a living cell.
• Viruses act like parasites, organisms that live
in or on another organism and cause it harm.

11. • The living organism that a virus attaches to and
uses as a source of energy is called the host.
• Once the host is carrying and transmitting a virus
it is referred to as a vector.
Viruses (Cont.)

12. Proteins on viral surface
play an important role
during the invasion of a
host cell.
The shape of the
surface proteins allow
the virus to attach to the
proteins on the surface.
General Structure of a Virus
Nucleic acid
core
(DNA/RNA)
Capsid
(Protein
coat)

13. How Viruses Multiply
Nucleic acid (DNA or RNA).
4. New viral nucleic acids are
packaged into viral particles
and released from the cell.
The host cell may be
destroyed in the process.
1. Virus attaches to a cell.
2. Virus
penetrates cell
membrane and
injects its nucleic
acid.
3. Viral nucleic acid
replicates using host
machinery.

14. Common Viruses
• Bacteriophage are robot like viruses that
infect bacteria
Head with nucleic
acid core
Tail with
spikes
Neck

15. Common Viruses
Common Cold -
Rhinovirus
The Flu –
Influenza
Virus

16. Common Viruses
Chicken Pox Measles

17. Common Viruses
HIV SARS

18. How is a virus transmitted?
Viruses can be spread in many ways:
• Contact with a contaminated object
• Bite of an infected animal.
• In sneezes and coughs
• Contact with body fluids such as blood.

19. How to treat viruses?
• There are currently no cures for viral diseases,
however, many over the counter medications
(antivirals) may help treat the symptoms.
• Resting, plenty of fluids, and well balanced
meals may be all you can do to help your
immune system fight a virus.

20. A vaccine is a substance introduced into the
body to trigger the body’s natural defense.
Oral Polio Injectable
Polio, BCG
Hepatitis B Cholera

21. Virus Multicellular organisms
Characteristics

22. Domains of Microorganisms
• Archea
• Viruses
• Bacteria
• Protists

23. Bacteria
• Bacteria were discovered by accident in the
late 1600’s by a Dutch merchant named
Anton van Leeuwenhoek.

24. Bacteria
Structure
• Bacteria are prokaryotes:
– No nucleus
– DNA in a loop in the cell
– Few organelles
– Usually have a cell wall
– Usually have a flagellum

25. How bacteria eat?
• Like all living things, bacteria need to have a sources of food
and a way to break that food down in order to survive.
• Most bacteria need oxygen to break their food down, but a
few do not require oxygen for respiration.

26. How do bacteria reproduce?
• Bacteria can reproduce: Asexually (one parent) by
means of binary fission: one cell divides into two
identical cells.
or
Sexually (two parents) by means of conjugation:
one bacteria transfers some genetic material to
another bacteria though a thread like bridge.

27. The Exceptional Bacteria
• Some bacteria can survive harsh conditions
like freezing, heating and drying by forming an
endospore.
• An endospore is a small rounded, thick
walled, resting cell that forms in a bacteria cell
and houses the bacterial DNA.

28. How do we transmit bacteria?
• In Sneezes, Coughs, Saliva:
(Pneumonia, Whooping Cough, Bacterial Meningitis)
• By Animal Vectors:
(bubonic plague, typhus)
• In Contaminated Food or Water:
(typhoid, salmonella, e. coli)

29. ● Antibiotics can only be used to treat bacterial
infections!
● Target specific structures on bacteria to kill them.
● First made from a fungus (penicillin), now most are
made artificially.
● Unfortunately, antibiotic resistance (where the
antibiotic doesn’t kill the target bacteria anymore) is
becoming a major problem.
How to kill bacteria? “Antibiotics”

30. History of antibiotics

32. MRSA Staphylococcus Resistance rates in the US

33. Gonorrhea resistant rates in the US

35. Domains of Microorganisms
• Archea
• Viruses
• Bacteria
• Protists

36. • Protists are eukaryotes that can not be classified as
animals, plants or fungi.

37. Animal-Like Protists
• Animal-like protists are heterotrophs and
most are able to move from place to place to
obtain food, however, unlike animals they are
unicellular.
• Animal-like protists may be called protozoans.

38. Animal-Like Protists
1. Protozoans with Pseudopodia (ex. Entamoeba histolytica)
1. Protozoans with Cilia (ex. Paramecium)

39. Animal-Like Protists (Cont.)
3. Protozoans with Flagella (ex. Peranema)
4. Protozoans that are Parasites (ex. Plasmodium)

40. Pseudopods (Amoeba)

41. Cilliates (Paramecium)

42. Plant-Like Protists
• Plant-like protists are commonly called algae.
They are grouped together because, like
plants, they are all autotrophs.
Diatoms Dinoflagellates Euglena

43. Plant-Like Protists
• Plant like protists play an important role in
ecosystems.
• They provide a source of food for many other
organisms
• They make much of the oxygen that makes up
the Earth's atmosphere.

44. Algae (Euglena)

45. Microbe-Human interactions

46. Normal flora
• Microbes that are normally found on or in the
human body without causing any disease.
• Internal organs, tissues and fluids are microbe-
free.
• Bacterial flora benefit host by preventing
overgrowth of harmful microbes.

48. •Where is the genetic material located in a bacteria
cell?...................
•What is the role of a flagella?.............
•What are three ways bacteria can obtain
food?................
•How do bacteria obtain energy to carry out their
functions?......................