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