2. What is MICROBIOLOGY??
•Very small to be seen
by naked eye
MICRO
•LifeBIO
•ScienceLOGY
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3. Microbiology:
Is the science that deals with the study of
micro-organisms ;their activities and their
influences on different aspects of life.
The term was introduced by the French
chemist Louis Pasteur.
What is MICROBIOLOGY??
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4. • The organisms are widely distributed in
nature.
• Some of them are beneficial to man and some
are harmful.
• Medical microbiology deals with microbes
that are harmful to man.
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5. The agents of human infections belong to
Microbes
Bacteria
Viruses
Fungi
Parasites
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6. Bacteriology: is the science studying bacteria.
Virology : is the science studying viruses.
Mycology: is the science studying fungi.
Parasitology: is the science studying parasites.
IMMUNOLOGY
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7. • Based upon cell characteristics, living
organisms are recognized as having
Eukaryotic or
Prokaryotic
cell type.
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8. Prokaryotes
• They are small cells.
• Don’t have a true nucleus, have anucleoid.
• Have a single chromosome (DNA).
• Have no nuclear membrane.
• Have a small ribosomes (70S).
• Reproduce by binary fission.
• Have a rigid cell wall containing peptidoglycan.
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9. Eukaryotes
• Have a true nucleus with a nucleolus
surrounded by a nuclear membrane.
• Contain organelles, such as mitochondria and
lysomsomes.
• Have multiple chromosomes.
• Cell division is by mitosis or meiosis.
• Ribosomes are large (80S).
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10. Characteristics of prokaryotic & eukaryotic cells
Characteristic Prokaryote Eukaryote
Size Relatively small Larger
DNA content Nucleoid Nucleus
Chromosome number One More than one
Mitochondria Absent Present
Nuclear membrane Absent Present
Size of ribosomes 70S 80S
Multiplication Binary division Mitotic
Enzyme system Simple Complex
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11. • Bacteria belong to the prokaryote kingdom.
• Fungi and parasites are members of eukaryote
kingdom.
• ?? viruses.
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12. Bacteria
• Are prokaryotic cells, so:
They are small and simple.
Their genetic material is a single naked.
chromosome without nuclear membrane.
Surrounded by a rigid cell wall.
They contain 70S ribosomes but no organelles,
and replicate by binary fission.
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13. Fungi
• Are eukaryotic cells with a complex cell wall
(chitin).
• Their cell membrane contains sterol.
• Have chromosomes which are enclosed by a
nuclear membrane and the cell contains
ribosomes and mitochondria.
• Exists as yeast, mold or both.
• Reproduce typically by asexual and sexual
mechanisms.
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14. Parasites
• Are eukaryotics.
• Either unicellular (protozoa) or multicellular
helminths (worms).
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15. Viruses
oAre not cells and not visible with the light
microscope.
oReplicate only in living cells and there for
are obligate intracellular parasites.
oContain NO organelles.
oContain either DNA or RNA surrounded by a
protein coat.
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16. Comparison of medically important organisms
Characteristic Viruses Bacteria Fungi Protozoa
helminthes
Size( µ) 0,02 - 0.2 0.2- 5 3 -10 15 -20
(trophozoite)
Nucleic acid DNA or RNA Both Both Both
Nucleus None Prokaryotic Eukaryotic Eukaryotic
Ribosomes Absent 70 S 80 S 80 S
Mitochondria Absent Absent Present Present
Nature of outer
surface
Protein capsid
& lipoprotein
envelope
rigid wall
containing
peptidoglycan
Rigid wall
containing
chitin
Flexible
membrane
Motility None Some None Most
Replication Not binary
fission
Binary fission Budding or
mitosis
Mitosis
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