microbiology lec1

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Microbiology Microbiology Lecture 1 Lecture 1 Dr. Saleh M Y OTH Dr. Saleh M Y OTH PhD PhD Medical Molecular Biotechnology and Infectious Diseases Medical Molecular Biotechnology and Infectious Diseases 02/10/2010 02/10/2010 IMS - MSU IMS - MSU

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Page 1: Microbiology   lec1

MicrobiologyMicrobiology

Lecture 1Lecture 1

Dr. Saleh M Y OTHDr. Saleh M Y OTH

PhDPhDMedical Molecular Biotechnology and Infectious DiseasesMedical Molecular Biotechnology and Infectious Diseases

02/10/201002/10/2010IMS - MSUIMS - MSU

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Microbiology is the science that deals with tiny organisms that can’t be seen by naked eye.

-micro=tiy, -bio=alive, -logy=science

Introduction

In general; we call this part of the science : Microbiology and the organisms called Microorganisms

These microorganisms are widley distributed in nature and some of them are beneficial to man and some of them are harmful (pathogenic; cause diseaes).

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In our field of medical microbiolgy, we deal with microbs that cause diseases to man.

Microbiology

Viruses = Virulogy

Bacteria = Bacteriolgy

Fungi = Mycology

Parasites = Parasitology

Immunity = Immunology

Antibiotics = in use for treament

Medical Microbiology

Food Microbiology

Water Microbiology

Air Microbiology

Soil Microbiology

Space Microbiology

Industrial Microbiology

Pranches of Microbiology

Algae = Phycology

Prtotzoa = Protozoology

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The harmful microbs (agents) called pathogens

Thus; the agents of human infecious diseases belong to 5 major groups:

1- Viruses

2- Bcateria

3- Fungi

4- Protozoa

5- HelminthsParasites

Viruses are quite distinct from the other organisms as they are NOT cells but can replicate only within cells.

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BACTERIA are microscopic unicellular Prokaryotes, the MOST Numerous Organisms on the Earth

Evolution and Classification of Bacteria

Bacteria have evolved into many different forms, and they are now part of nearly every environment on the Earth. 

They have been found at the bottom of the oceanic trenches 9.6 km (6 mi) below the water's surface and in Arctic and Antarctic Regions.

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Evidence in the fossil record indicates that Prokaryotes are about 2.5 Billion Years Old and Modern Humans arose about 100,000 years ago.

Unlike most other organisms, Bacteria have few Morphological differences that can be used to classify them.

Bacteria do Not vary in size and shape to the extent that other types of organisms do.

Classicaly, bacteria have been grouped based on their Structure, Physiology, Molecular Composition, and Reaction to specific types of stains (Gram Stain), rather than on their evolutionary relationships.

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Bacteria can be one of THREE Different SHAPES: 

The three common types of bacterial morphology;

Cocci - coccus, Bacilli - bacillus, spirillum

These types: spherical, rod and sprial shaped morphologies are typical of such genera as: Streptococcus / Staphylococcus, Escherichia / Bacillus and Leptospira / Spirillum.

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Bacteria are all around us. Bacteria are all around us.

Given good growing conditions, a bacterium grows slightly in size Given good growing conditions, a bacterium grows slightly in size or length.or length.

A new cell wall grows through the center forming two daughter A new cell wall grows through the center forming two daughter cells, each with the same genetic material as the parent cell. cells, each with the same genetic material as the parent cell.

If the environment is optimum, the two daughter cells may divide If the environment is optimum, the two daughter cells may divide into four in 20 minutes. into four in 20 minutes. That mins: 1, 2, 4, 8, 16, 32, 64... Then why isn't the earth covered That mins: 1, 2, 4, 8, 16, 32, 64... Then why isn't the earth covered with bacteria...?with bacteria...?

Bacteria: growth, divide and multiply

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The primary reason may be that conditions are rarely The primary reason may be that conditions are rarely optimum. optimum.

Scientists who study bacteria try to create the optimum Scientists who study bacteria try to create the optimum environment in the lab: culture medium with the environment in the lab: culture medium with the necessary energy source, nutrients, pH, and temperature, necessary energy source, nutrients, pH, and temperature, in which bacteria grow predictably.in which bacteria grow predictably.

Bacteria: growth, divide and multiply

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1- LAG PHASE: Growth is slow at first, while the "bugs" acclimate to the food and nutrients in their new habitat.

1

2

3

4

2- LOG PHASE: Once the metabolic machinery is running, they start multiplying exponentially, doubling in number every few minutes.

3- STATIONARY PHASE: As more and more bugs are competing for dwindling food and nutrients, booming growth stops and the number of bacteria stabilizes.

4- DEATH PHASE: Toxic waste products build up, food is depleted and the bugs begin to die.

Growth Curve

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STRUCTURE of the BACTERIAL CELL

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Bacteria are Typically composed of:

Cell Wall,

Cell Membrane, and

Cytoplasm 

Some bacteria have Distinctive Structures, such as Endospores, Capsules, and Outer Membranes.

The Variety of Structures among Bacteria is due to adaptations to individual to take its place in the world.

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Capsule

Cell walPlasma membrane

Cytoplasm

Riposomes

Plasmid

Pili

Nucleoide (circular DNA)

Bacterial Flagellum

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CELL WALL

bacteria have a Cell Wall and its function is to protect the bacterial cells from bursting or destroys and gives the bacteria its shape.

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CELL MEMBRANE AND CYTOPLASM

1. The Bacterial Cell Membrane is composed of a Lipid Bilayer similar to Eukaryotes.

2. In Bacteria, the cell membrane contains Enzymes that Perform the Reactions of Cellular Respiration.

3. Bacteria do NOT have Mitochondria so they use their cell membranes to carry out Cellular Respiration.

4. Bacterial cells do NOT have membrane bound organelles.  The CYTOPLASM of Bacterial cells is made of a Viscous (Thick Liquid) solution of Ribosomes and DNA.

5. The Bacterial DNA is arranged in a single, closed loop.  Some bacteria also have PLASMIDS, self-replicating loops of DNA, in their Cytoplasm.

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Capsules and Pili

1. Many bacterial species produce an Outer Covering called a CAPSULE.  The capsule is made of polysaccharides that cling to the surface of the cell and Protect It against drying or harsh chemicals and a host body's white blood cells, which would otherwise engulf (eat) it.

2. When a Capsule consists of a Fuzzy Coat of Sticky Sugars, it is called a GLYCOCALX (GLIE-koh-KAY-liks).  The Glycocalyx enables bacteria to attach to the surface of host cells and tissue.

3. PILI are Short, Hairlike Protein Structures found on the Surface of some species of bacteria.  Pili help bacteria hold on to host cells, and are also used to transfer genetic material from one bacterium to another.

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STRUCTURAL CHARACTERISTICS OF A BACTERIAL CELL

STRUCTURE FUNCTIONCell Wall protects the cell and gives shape

Outer Membraneprotects the cell against some antibiotics (only present in Gram-negative cells)

Cell Membraneregulates movement of materials into and out of the cell;  contains enzymes important to cellular respiration

Cytoplasmcontains DNA, ribosomes, and organic compounds required to carry out life processes

Chromosomecarries genetic information inherited from past generations

Plasmidcontains some genes obtain through genetic recombination

Capsule, and slime layer protects the cell and assist in attaching the cell to other surfaces

Endosporeprotects the cell against harsh environmental conditions, such as heat or drought

Pilus (Pili)assist the cell in attaching to other surfaces, which is important for genetic recombination

Flagellum moves the cell

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