3. What is Microbiology?
Microbes, or microorganisms are minute living
things that are usually unable to be viewed with the
naked eye.
What are some examples of microbes?
Bacteria, fungi, protozoa, algae, viruses are
examples!
Some are pathogenic
Many are beneficial
Dr.T.V.Rao MD 3
6. Dutchman anton van leeuwenhoek observed
microorganisms>>”animalcules” suspended in a drop of
pond water in front of a ground hand lens
6
7. History; contd.
ROBERT HOOKE built simple compound microscope and observed
structure of thin layer of cork>>used the word “CELLS”
Theory of spontaneous generation: from non-living matter
Theory of biogenesis: from preexisting living cells
LOUIS PASTEUR>>Pasteur’ experiment>>boiled nutrient broth in a
flask & curved it in to S-shape>>after cooling>>bacteria trapped in
curve but no organism in flask; dicovered souring in alcohol is due
to fermentation and can be prevented by heating wine at56oC for
30mins…..now called PASTEURISATION>>
7
8. History contd;
IGNAZ SEMMELWEIS was concerned at high incidence of puerperal
fever and latter instituted hand washing in chlorinated solutions;
ridiculed by colleagues and was dismissed; died of
STREPTOCOCCAL INFECTION
JOHN SNOW: transmission of cholera due to contamination of the
river Thames….later confirmed by ROBERT KOCH in German
8
9. Bacteriology is the study of bacteria.
Mycology is the study of fungi.
Parasitology is the study of protozoa and
parasitic worms.
Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms.
Proteomics is looking at the gene products
Definitions
3/10/2014Dr.T.V.Rao MD 9
10. Classification of micro-organisms
All living organisms are classified into:
Kingdom
Phylum (family)
Genus
Species
Organisms that can cause disease are many and varied
and include:
Viruses
Bacteria
Fungi
Parasites 3/10/2014Dr.T.V.Rao MD 10
13. Prokaryotic cells Eukaryote cells
Small cell (< 5µm) Larger cells (> 10 µm)
Always unicellular Often multicellular
No nucleus or any membrane bound organelles Always have nucleus and membranes bound
organelles.
DNA circular, without proteins DNA is linear and associated with proteins to
form chromatin.
Ribosomes are small 70S Ribosomes are large 80S
No cytoskeleton Always have cytoskeleton
Motility by rigid rotating flagellum made from
flagellin
Motility by flexible waving cilia or flagella
made from tubulins.
Cell division is by binary fission Cell division is by meiosis and mitosis.
Reproduction is always asexual Reproduction is sexual and asexual.
Summary of differences between
prokaryote and eukaryote cells
14. Prokaryotic Cell Structure
• Prokaryotic cells are about 10 times smaller
than eukaryotic cells.
• prokaryotes are very simple cells when
compared with eukaryotic cells,
• Reproduction of prokaryotic cells is by binary
fission, the simple division of one cell into two
cells.
15. Bacteria
Prokaryotes
Peptidoglycan cell
walls
Binary fission
For energy, use
organic
chemicals, inorganic
chemicals, or
photosynthesisDr.T.V.Rao MD 15
18. Capsule stain. The capsule stain is an example of a negative staining technique. The
bacterial cells and the background stain, but the capsules do not. The capsules are
seen as unstained “halos” around the bacterial cells.
19. Binary fission. Note that DNA replication must occur before the actual
splitting (fission) of the parent cell.
21. Viruses
Viruses lack many of the attributes of cells, including the ability
to replicate. Only when it infects a cell does a virus acquire the
key attribute of a living system: reproduction
A viral particle consists of a nucleic acid molecule, either DNA
or RNA, enclosed in a protein coat, or capsid
Viruses are known to infect all cells, including microbial cells.
Host-virus interactions tend to be highly specific
Dr.T.V.Rao MD 21
22. Discovery of Virus
Iwanovski
a Russian chemist, 1892
Tobacco Mosaic Disease
Beijerinck confirmed
Walter Reed, USA
Yellow fever virus
Ist human virus
Tobacco mosaic disease,
caused by the tobacco
mosaic virus
Dr.T.V.Rao MD 22
23. Viruses
A virus is not a cell!
Viruses are replicated only when
they are in a living host cell
Consist of DNA or RNA core
Core is surrounded by a protein
coat
Coat may be enclosed in a lipid
envelope
Dr.T.V.Rao MD 23
24. What are Viruses
Viruses Dependent on Host cells
for necessary functions and
Multiplication
Intracellular parasites
Contain either DNA or
RNA never both.
Dr.T.V.Rao MD 24
25. Fungi
Complex, large organisms
Eukaryotes (as are
humans!)
Divided into yeasts &
moulds
Cause a range of diseases
e.g.:
Thrush
Athletes foot
Invasive & allergic
aspergillosis
Many diseases are
opportunistic.
3/10/2014Dr.T.V.Rao MD 25
27. Multicellular Animal Parasites
Eukaryote
Multicellular animals
Parasitic flatworms and round worms are called Helminths.
Microscopic stages in life cycles.
Figure 12.28a
3/10/2014Dr.T.V.Rao MD 27
28. Disease-causing microorganisms
are called pathogens.
Pathogenic microorganisms have
special properties that allow
them to invade the human body or
produce toxins.
When a microorganism overcomes
the body’s defenses, a state of
disease results.
Diseases and Infections
3/10/2014Dr.T.V.Rao MD 28
29. Pathology, Infection, and Disease
Pathology is the scientific study of disease.
Pathology is concerned with the
etiology (cause),
pathogenesis (development),
effects of disease – structural and functional changes
brought about by disease.
Infection is the invasion and growth of pathogens in the body.
A host is an organism that shelters and supports the growth of
pathogens.
Disease is an abnormal state in which part or all of the body is
not properly adjusted or is incapable of performing normal
functions.
Infection disease – presence of particular microorganism in part
of the body where is not usually found. 3/10/2014Dr.T.V.Rao MD 29
30. Classifying Infectious Diseases
Communicable diseases are transmitted directly
or indirectly from one host to another.
Chicken pox, genital herpes,
A contagious disease is one that is easily
spread from one person to another.
Noncommunicable diseases are caused by
microorganisms that normally grow outside the
human body and are not transmitted from one host
to another
Tetanus, Clostridium tetani
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31. Recombinant DNA Technology
Genes in
microbes, plants, and animals
manipulated for practical
applications
Production of human blood-
clotting factor by E. coli to
aid hemophiliacs
Gene Therapy
Inserting a missing gene or
repairing a defective one in
humans by inserting desired
gene into host cells
The Modern Age of Microbiology
3/10/2014Dr.T.V.Rao MD 31
32. Discovery of Antimicrobial Agents
_________
Alexander Fleming (1881 – 1955), a
Scottish biologist and
pharmacologist, observed
bacterial staphylococci colonies
disappearing on plates
contaminated with mold.
Fleming extracted the compound
from the mold responsible for
destruction of the bacterial
colonies.
The product of the mold was
named penicillin, after the
Penicillium mold from which it
was derived.
Nobel Prize in Physiology of
Medicine in 1945.
Images: Penicillium mold, PHIL #8396; Staphylococcus aureus on
antibiotic test plate, PHIL #2641; Poster attached to a mailbox
offering advice to World War II servicemen, 1944, NIHFrom the Virtual Microbiology Classroom on ScienceProfOnline.com
3/10/2014 Dr.T.V.Rao MD 32
33. The Modern Age of Microbiology
How Do We Defend Against Disease?
Serology
The study of blood serum
Von Behring and Kitasato – existence in the blood
of chemicals and cells that fight infection
Immunology
The study of the body’s defense against specific
pathogens
Chemotherapy
Fleming discovered penicillin
Domagk discovered sulfa drugs
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34. REFERENCES
Picture on slide no: 1 taken from
http://www.123rf.com/photo_10012159_background-concept-wordcloud-
illustration-of-microbiology-science--microorganisms.html
Picture on slide no: 15 taken from;
http://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/Average_prok
aryote_cell-_en.svg/494px-Average_prokaryote_cell-_en.svg.png
HISTORY OF MICRO ORGANISMS AND PICTURES, DR PRABESH K CHOUDHARY
http://www.authorstream.com/Presentation/prabeshc-1456031-medical-
microbiology-introduction/ 2001
35. Definition of terms; Dr.T.V.Rao
MD, http://www.authorstream.com/Presentation/doctorrao-1594767-
microbiology-medical-graduates/ , 2014
Notes on classification and pictures, DR PRABESH K CHOUDHARY
http://www.authorstream.com/Presentation/prabeshc-1456031-medical-
microbiology-introduction/
Microbes diseases and pictures, R
Saravanan, http://www.authorstream.com/Presentation/rssrmcp-923598-
introduction-of-microbiology-saravanan/ , 2010
NOTES BACTRIA AND VIRUS and pictures, vidhyakalai
http://www.authorstream.com/Presentation/vidhyakalai-1897393-history-
microbiology-vidyakalaivani/ 2000