Disease Many different organisms cause disease. This presentation will show you some organisms that cause disease and the diseases they cause.

Bacteria

Bacteria are believed to be the oldest, of all life forms found on earth today.

Bacteria are prokaryotes.Bacteria do not have a nucleus.There are two kingdoms of bacteria:

– Archaebacteria– Eubacteria

Bacteria come in 3 different shapes:

Coccus: sphere-shaped cellsBacillus: rod-shapedSpirillum: shaped like coiled

rods or corkscrews

Bacilli bacteria

Cocci bacteria

Spirilla bacteria

Structure of a Bacteria Cell Most bacteria have a rigid cell wall.Many bacteria are surrounded in a capsule.

– The capsule protects the bacteriaDNA is not found in a nucleus. Many bacteria have one or more flagella.

(For movement)Bacteria are covered with pilli.

– This allows bacteria to attach to another surface.

Structure of bacteria

Identifying bacteria

A very important test used to identify bacteria is the gram stain.

This technique was developed by the Danish microbiologist Hans Christian Gram.

Gram Staining

In this process bacteria are put onto a slide and stained with purple dye.– Bacteria that retain the purple dye are gram

positive.– Bacteria that do not keep the purple dye are

gram negative.

• The difference in staining is due to the composition of their cell walls.

Gram Staining

• Gram negative bacteria have a protective layer covering their cell wall.

• This covering makes them more resistant to drugs and other chemicals that destroy bacteria cells.

• Antibiotics are more effective against gram-positive bacteria.

                             

Gram negative gram positive

Gram staining example

Steps of Gram-staining

Comparison of gram negative & gram positive bacteria

Nutrition in bacteria

Most bacteria are heterotrophic. They use organic compounds made by other organisms.

Many are decomposers. They obtain their nutrition from dead organisms.

Some bacteria are parasites. They live in or on another organism. (Disease causing bacteria)

Nutrition in bacteria

Some bacteria live in a state of mutualism. Both host and bacteria benefit from this type of association.– Example: intestinal bacteria in humans and nitrogen fixing

bacteria in the roots of some plants.

Some bacteria are photosynthetic. Some bacteria obtain energy from the oxidation of

inorganic substances instead of from the sunlight.– Nitrifying bacteria: can oxidize ammonia to nitrates.

These are root nodules on the roots of a bean

plant.  The nodules contain

the nitrogen fixing bacteria

Rhizobium.

Nitrogen fixation

Bacteria reproduction Most Bacteria have a very simple way of

reproducing.They simply split in two in the process

called binary fission.They double their DNA and divide.

Binary Fission

Disease Causing BacteriaThere are many different

types of disease causing bacteria. The following slides are just a few of the many examples.

Anthrax

Bacillus anthracis

Bacillus anthracis is the causative agent of anthrax. It is a Gram-positive, aerobic, spore-forming large bacillus. Spores are formed in culture, in the soil, and in the tissues and exudates of dead animals, but not in the blood or tissues of living animals. Spores remain viable in soil for decades.

Anthrax

Cutaneous anthrax

The Anthrax Scare

The letter that contained anthrax spores

The Bubonic Plague

Plague is caused by  Yersinia pestis and is the disease known in the middle ages as the black death. This is because it frequently leads to gangrene and blackening of various parts of the body. Capillary fragility results in hemorrhages in the skin which also result in black patches.

The Bubonic Plague

The three documented pandemics of plague (Black Death) have been responsible for the death of hundreds of millions of people. Today, sporadic infections still occur. In the U.S., animal plague occurs in a number of western states, usually in small rodents and in carnivores which feed on these rodents.

The Bubonic Plague

PANDEMIC- AFFECTING A LARGE AREA, WIDESPREAD

The Bubonic Plague

Buboes (Swollen lymph node)

The Flea that carries the plague

Gangrene caused by the plague

The Bubonic Plague

Drawing of the outfit that people would wear to prevent from smelling or coming in contact with the dead .