Microorganisms and DiseaseChapter 1Lesson 5

Microorganisms

• Microorganisms are organisms that are microscopic, or too small to be seen with just the eyes.

• They can be unicellular or multicellular.• Microorganisms are EVERYWHERE!!! They are

in food that you eat, on your books, and inside your body.

Microorganisms are helpful.

• They provide larger organisms with some of the food and oxygen they need to survive.

• They also enrich the environment by breaking down dead organisms.

Microorganisms can be harmful.

• A disease is anything that interferes with the normal functions of the body.

• Some diseases are caused by harmful materials in the environment, but many are caused by microscopic agents. These agents are called pathogens.

• Some types of bacteria, viruses, protists, and fungi can cause diseases.

Infectious Diseases

• Diseases caused by pathogens that can be passed from one organism to another are called infectious diseases.

• Pathogens can be transmitted from direct contact with an infected individual. They also can be transmitted through the air if a person touches a contaminated object.

• Animals can pass pathogens to people.

Have you ever had a sore throat and gone to the doctor?

• What did the doctor do to check your throat?• Your doctor probably used a cotton swab and

rubbed it on the back of your throat. They do this to pick up some bacteria from your throat.

• This is called a throat culture. They place the sample from the cotton swab on a special plate and see if a bacterium grows. This bacterium is called Streptococcus. It attacks cells in the throat and causes a disease we call strep throat.

Harmful Bacteria

• Some bacteria cause disease by producing poisonous substances called toxins.

• Tetanus and scarlet fever are examples of diseases caused by toxins.

Bacteria can live on food.

• It can live on uncooked meats, raw eggs, and other foods.

• Examples of these bacteria are E.coli and Salmonella. They both attack the digestive system by damaging cells in the intestines and stomach.

Lyme disease

• This is also caused by bacteria. • The bacteria can enter a person’s body when

he or she is bitten by a tick that carries it.

Harmful Fungi

• Have you ever had or heard of athlete’s foot? This is caused by a fungus that is found in damp places and lives on skin. It can cause flaky skin and itching.

Harmful Protists

• Dysentery is a disease caused by a protist. It is spread by amoebas that enter an organism’s body by contaminated food or water.

• Sleeping sickness is also caused by a protist. This protist lives in the bodies of cows and other animals. Flies can transfer the protist to humans.

• Malaria is a disease caused by mosquitoes that transmit the protist that causes malaria form one person to another. Once it’s inside the body, the protist reproduces in the person’s red blood cells and destroys them.

Microorganisms can harm plants.

• In the 19th century, a protist spread throughout Ireleand and destroyed large amounts of potato crops. The disease caused by the protist is known as potato blight.

Protecting ourselves from harmful microorganisms

Famous Scientists:• Louis Pasteur- developed a process to

eliminate microbes from some foods. This process heats liquids, such as milk, to high temperatures and the heat destroys bacteria without significantly altering the liquid. This process is known as pasteurization.

• Cooking food also destroys many harmful bacteria.

Famous Scientists• Alexander Fleming-

Discovered the first antibiotic, penicillin in 1928.

• Antibiotics are chemicals used to treat bacterial infections. They stop the growth of bacteria.

• Today we have many different antibiotics. Each one works for only certain types of bacteria.

Famous Scientists

• Edward Jenner- Created the first vaccine in 1796. It was used to treat smallpox.

• Jonas Salk- Created a vaccine to prevent a viral disease caused polio in the 1950s.

• A vaccine is made from dead or weakened pathogens. Vaccines can prevent you from getting certain diseases.

What is the best way to stop the spread of most infectious diseases?

• Just WASH your HANDS! This simple act can remove the pathogens you might pick up and help prevent the spread of diseases. So wash up!!!

What are some common microorganisms?

•Bacteria• Some fungi• Some protists

Why are microorganisms important?

• Microscopic organisms provide larger organisms, including people, with some of the food and oxygen they need to survive. Some microscopic organisms enrich the environments by breaking down dead organisms.

Are microorganisms unicellular or multicellular?

•Microorganisms include unicellular and multicellular organisms.

What are some examples of unicellular protists and fungi?

• Unicellular protists- amoeba, paramecium, Euglena

• Unicellular fungi- yeast

What would happen if microorganisms disappeared from Earth?

• If microorganisms disappeared from Earth, many larger organisms would be without a food source. Nutrients would not be recycled through an environment.

Think about a time when you have been sick. What might have caused you to get sick?

Where do bacteria that cause a form of pneumonia attack the body?

• The lungs• How are diseases such as tetanus or

scarlet fever caused?• By bacteria that produce poisonous

substances called toxins

What kinds of bacteria can attack the digestive system after someone was in contact with

uncooked food?

• E. coli and salmonella

What diseases are caused by harmful fungi?

• Athlete’s foot• How are the microorganisms that destroyed

potato crops throughout Ireland in the nineteenth century similar to the ones that cause malaria?

• They are similar because they are both protists.• Where do protists that cause malaria reproduce?• Inside red blood cells

• During what time of year do the number of Lyme disease cases increase?• summer

How are diseases spread?

• Some diseases are caused by organisms, such as some bacteria. Disease can also be spread when a healthy individual comes in contact with an individual who is sick. Some disease occur when people eat uncooked food. Animals can also spread disease.

Why is the term agent more accurate than organism when defining a pathogen?

• Organisms are living things. Viruses are not living. Because viruses can cause disease, it is more accurate to use the term agent instead of organism when defining a pathogen.

• Why do scientists develop different antibiotics?

• Not all antibiotics work on all bacteria, so scientists are continually trying to find new antibiotics that will work on different types of bacteria.

How does the process of pasteurization help keep us safe from disease?

• Pasteurization destroys harmful bacteria found in foods such as milk.

Look closely at the word antibiotic.

• What is the prefix?• anti- this means “opposed to” or “against”• The word biotic relates to life or living

organisms. • Antibiotics inhibit the growth of living microorganisms like bacteria.

Vaccines

• Vaccines contain pathogens that have been killed so that they are not longer harmful. The vaccines help prevent disease by “training” the body’s defenses to attack specific pathogens.

What are some ways to prevent the spread of infectious diseases?

• Washing your hands • Getting vaccinations

Antibiotics kill certain bacteria. Why don’t they kill all bacteria?

• There are many different types of bacteria. Because not all bacteria are the same, different chemicals are needed to kill bacteria.