introductio n to microbiolog y Prepared by :Safa Omar Elate Hend mansor issa
introduction to
microbiologyPrepared by :Safa Omar
ElateHend mansor issa
Why Study Microbiology?
1 .Impact on Human Health
2 .Balance of Nature
3 .Environmental
4 .Industrial
5 .Agricultural
Microbiology defined
Microbiology defined - The study of microbiology is the study of microorganisms, which are organisms that are invisible to the naked eye except in large groups .
Microorganisms: Normal flora Pathogenic
Brief History of Microbiology
Pioneers of Microbiology
Leeuwenhoek (lived 1632-1723).First person to use microscopes to observe microbes; as a
hobby he made small handheld microscopes; he called microorganisms “animalcules”.
Robert Hooke, UK (1665) He first described “cellulae” (small rooms) in cork in
1665. His discovery led to the formulation of the cell theory, which states that cells are the basic organizational unit of all living things.
Living organisms arise from nonliving things (ex. maggots come
from rotting meat).
In the late 1600’s Francisco Redi showed that maggots developed only in meat that flies could reach to lay eggs on.
Many insisted that he only disproved spontaneous
generation for Macroorganisms ; maybe microbes were an exception.
Spontaneous generationSome forms of life could arise spontaneously from non-living matter.
Francisco Redi (1668):
Brief History of MicrobiologyPioneers of Microbiology
Louis Pasteur (1822-1895), Chemist:
Fermentation (1857). Pasteurization: heat liquid enough to kill spoilage bacteria
(1864). Vaccine development – rabies. Proposed the germ theory of disease. Proposed aseptic techniques (prevent contamination by
unwanted microbes). Director of Pasteur Institute, Paris (1894).
Brief History of MicrobiologyPioneers of Microbiology
Classification and Naming of Microorganisms
Classification by structure
Subcellular – DNA or RNA surrounded by a protein coat – viruses
Prokaryotic – simple cell structure with no nucleus or organelles – bacteria
Eukaryotic – complex cell structure with nucleus and specialized organelles – protozoans, fungi, parasites
Standardized namingo Genus
Category of biologic classification Example – Staphylococcus
o Species of organism Represents a distinct type of
microorganisms Examples – Staphylococcus aureus
and Staphylococcus epidermidis
Classification and Naming of Microorganisms
All cells have:1 .Cell or plasma membrane (separates the cell from
the outer environment)2 .Genetic material (DNA)
3 .Cytoplasm.
Characteristics of Prokaryotic & Eukaryotic Cells
However, within this general description we find many different types of cell. The most important divide is between Prokaryotic (Pro – before, karyote – nucleus) and Eukaryotic cells.
Prokaryotic cells are : o comparatively simple, and small.o The DNA is found in circles or loops and it floats in cytoplasm.o Ribosomes (70S in size) are also found in the cytoplasm.
o While some cells have internal membranes, most have only a porous outer membrane with a semi permeable inner membrane.
Prokaryotic cells
Eukaryotic cells are structurally complex and they are generally larger than bacterial cells.
Eukaryote cells have membrane bound organelles. Their DNA is organized into linear threads called
chromosomes which are located within a membrane, and the entire unit is called a nucleus.
Organelles that might be found in a cell include ribosomes (80S), mitochondria, chloroplasts and golgi.
The organelles are linked by membranes. Their position and the activity of organelles within the cell is regulated by the cytoskeleton .
The cytoskeleton has two main components, microfibrils made of actin and microtubules made of tubulin . Animals, Plants, Fungi ,Protista are found within the Eukaryota.
Eukaryotic cells