Viruses, Bacteria, and FungusHow they affect us!

What are Viruses

• A virus is a tiny, non-cellular, non-living particle that enters and then reproduces inside a living cell.

• All viruses have two basic parts: A protein coat that protects the virusAn inner core made of genetic

material (contains the instructions for making new viruses)

Vary in shapes and sizesThese round viruses are responsible for causing West Nile disease in animals.

This robotlike virus, called a bacteriophage, infects bacteria.

Once inside the cell, the virus’s genetic material takes over many of the cell’s functions. It instructs the cell to produce the virus’s proteins and genetic

material. These proteins and genetic material then assemble into new viruses.

• Active Viruses• 1. A virus attaches to the surface of a

bacterium.• 2. The virus injects its genetic material

into the bacterium.• 3. The virus’s genetic material takes

over the cell functions of the bacterium. The cell starts to produce the virus’s proteins and genetic material.

• 4. The proteins and genetic material assemble into new viruses that fill the bacterium.

• 5. The bacterium bursts open, releasing new viruses. The viruses go on the infect more cells.

• Hidden Viruses• 1. A virus attaches to the surface of a

bacterium.• 2. The virus injects its genetic material

into the bacterium.• 3. The virus’s genetic material becomes

part of the genetic material of the bacterium.

• 4. After some time, the virus’s genetic material removes itself and becomes active.

• 5. The cell begins to produce the virus’s proteins and genetic material, which assemble into new viruses.

• 6. The new viruses crowd the bacterium. Finally, the cell burst open and releases the new viruses.

The Bad and The Good• Viruses and Diseases

• Mild viral diseases last for short times with quick recovery (colds)

• Serious viral diseases have more serious effects on the body (AIDS)

• Viruses do not affect only humans but also plants and animals

• Apple trees – Apple Mosaic Virus• House pets (dogs and cats) –

rabies and distemper

• Usefulness of Viruses

• In gene therapy, genetic material is added to a virus to use the virus as a “messenger service” to deliver to affected cells

• For example: for the treatment of cystic fibrosis

Bacteria

DNA

Anton Van Leeuwenhoek

• Discovered bacteria by accident while looking at scrapings from his teeth

Prokaryotic Cells• Also called bacteria• World’s smallest cells• No nucleus• Circular DNA (shaped like a rubber band)• No membrane-covered organelles• Contains cytoplasm and ribosomes• Some may have a flagellum for movement

Prokaryotes• Cells that do not

have a nucleus• Exist almost every

where on earth• Grow in numbers so

great you can see them with the unaided eye

Bacterium Shapes• Cocci~ Sphere

shaped bacteria• Bacillus~ Rod

shaped bacteria• Spirrillium ~ Spiral

shaped bacteria• Flagella~ Leg-like

structures that help to propel the bacterium.

Movement - Bacteria

• Flagella ~ Tail like structure the whips around to propel the bacterium

How bacteria eat?Autotrophs Make their own energy

Using Solar energyEg. Cyanobacteria

Make own EnergyUsing Chemical energyEg. Archaebacteria

Chemotrophs

Heterotrophs Obtain food by eatingEg. E-coli

Respiration• Bacteria need a constant supply of energy to

carry out their functions. • This energy comes from the food they eat.• The process of breaking down food to release

energy is called RESPIRATION.• A few bacteria do not need oxygen to break

down their food.- anaerobic• Some bacteria die if oxygen is present in their

surroundings.

Bacterial Reproduction• Binary Fission• Cellular organism

copies it’s genetic information then splits into two identical daughter cells

• Asexual reproduction

• Conjugation• Two bacteria swap

genetic information through a thread-like bridge

• Sexual reproduction

Sometimes, conditions in the environment become “UNFAVORABLE” for the growth of bacteria. Ex. No food source, too dry, too wet, too hot, too cold

Bacteria will form endospores to survive these conditions. An endospore is a small, rounded, thick-walled, resting cell that forms inside the bacterial cell.

Symbiosis•Close relationship between two species in which at least one species benefits from the other•Live together for LIFE

Parasitism•Bacteria exploit the host cell, injuring them

Mutualism•Symbiosis in which two of the species live together in such a way that both benefit from the relationship•Eg. E-coli

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The role of Bacteria in Nature

Oxygen Production -

Food Production

Environmental Recycling

Environmental Cleanup

Health and Medicine

• Oxygen Production – Autotrophic bacterial use the sun’s energy to produce food with oxygen as a product.

• Food Production – Bacteria is used to make vinegar, buttermilk, yogurt, sour cream, and cheeses. (Food is heated enough to kill most harmful bacteria through a process called pasteurization.)

• Environmental Recycling – Decomposers are organisms that break down chemicals on dead organisms into small chemicals.

• Environmental Cleanup – Some bacteria help clean up Earth’s land and water. Some bacteria prefer to eat oil. They convert the poisonous chemicals in oil into a harmless substance.

• Health and Medicine – You have natural bacteria in your stomach to help with digestion. Some help your body make needed vitamins. Others compete for space preventing harmful bacteria from taking up residency. Bacteria is used to make human insulin for diabetic patients.

Nitrogen Fixations• Process by which nitrogen in the atmosphere

is converted into a form that can be used by living things by bacteria.

Viruses, Bacteria, and Your Health

• Infectious diseases – illnesses passed from one organism to another

Can spread through:Contact with an infected personA contaminated objectInfected animalAn environmental source

How infectious diseases are spread

Infected person –Direct - touching, hugging,

kissing Indirect -inhaling drops from a sneeze or cough

Contaminated Objects – Sharing eating and drinking objects

touching contaminated surfaces

Infected Animals –

Animal bites

Environmental Sources –

Food, soil, water

Antibiotic

• A chemical that can kill bacteria without harming a person’s cells

Antibiotic resistance

• When some bacteria are able to survive in the presence of an antibiotic

Toxin

• A poison that can harm an organism

Vaccine

• A substance introduced into the body to stimulate the production of chemicals that destroy specific viruses or bacteria

Antibiotics and Bacterial Diseases

Lyme DiseaseSymptoms: rash at bite, chills, fever, body aches,

joint swellingSpread: bite from

infected tickTreatment: Antibiotic

Prevention: Tuck pants into socks; wear long –

sleeved shirt

TuberculosisSymptoms: fatigue, mild fever. Weight loss, night

sweats, coughSpread: Inhaling droplets

Treatment: AntibioticPrevention: Avoid

contact with people with active infection: vaccine (for those at high risk)

TetanusSymptoms: Stiff jaw and neck muscles, spasms, difficulty swallowing

Spread: Deep puncture wound

Treatment: Antibiotic; opening and cleaning

woundPrevention: Vaccine

Antibiotics and Bacterial Diseases

Strep ThroatSymptoms: Fever, sore throat,

swollen glandsSpread: Inhaling droplets; contact

with a contaminated objectTreatment: Antibiotic

Prevention: Avoid contact with infected people; do not share

utensils, cups, or other objects

Food PoisoningSymptoms: vomiting, cramps,

diarrhea, feverSpread: Eating food containing the

bacteriaTreatment: Antitoxin medicinesPrevention: properly cook and

store foods; avoid eating foods in rusted and swollen cans

Vaccines and Viral Diseases

InfluenzaSymptoms: high fever, sore

throat, headache, coughSpread: Contact with

contaminated objects; inhaling droplets

Treatment: bed rest; fluidPrevention: Vaccine

Hepatitis C

Symptoms: often no symptoms; jaundice (yellowing of the eyes and

skin) fatigueSpread: Contact with blood of an

infected personTreatment: Drugs to slow viral

multiplicationPrevention: Avoid contact with infected

blood

Vaccines and Viral Diseases

Chicken PoxSymptoms: fever; red, itchy

rashSpread: contact with the rash;

inhaling dropletsTreatment: Antiviral drugs (for

adults)Prevention: Vaccine

Acquired Immunodeficiency Syndrome (AIDS)

Symptoms: weight loss; chronic fatigue; fever; diarrhea; frequent infectionsSpread: sexual contact; contact with

blood; pregnancy, birth, and breastfeeding

Treatment: Drugs to slow viral multiplication

Prevention:Avoid contact with infected bodily

fluids

Fungi• Fungi are-Eukaryotic cells that have cell wallsHeterotrophs that feed by absorbing their

foodUse spores to reproduce

Size and labeling• Tiny unicellular yeasts• Larger multi-cellular

fungi• Largest is an

underground fungus as big a 1,000 football fields

• Hyphae – the branching, thread-like tubes that make up the bodies of multi-cellular fungi.

Although fungi are heterotrophs, they do not take food into their bodies as you do.

• Instead, fungi absorb food through hyphae that grow into the food source.

• Then, digestive chemicals ooze from the hyphae into the food.

• The chemical breaks down the food into particles small enough to be absorbed by the hyphae.

Fungi Reproduction

• Fungi usually reproduce by making spores. The lightweight spores are surrounded by a protective covering and can be carried easily through are or water to new sites.

• Spores are produced in the fruiting bodies.

• Even though fungi produce millions of spores, only a few will land where conditions are right for survival.

• Yeast- reproduce by budding

Most fungi reproduce both asexually and sexually.

Spores

• When there is adequate food and moisture.

Budding

• A small yeast cell grows from the body of a parent cell and then breaks away and lives on its own.

Sexual Reproduction

• When growing conditions become unfavorable, the hyphae of two fungi grow together and genetic material is exchanged.

Classification of Fungi

Club Fungi – Produce spores

Includes: mushrooms and

puffballs

Zygote Fungi – Produce spores

Includes: common fruit and bread molds, such as

Rhizopus

Sac Fungi – Produces spores

Includes:Yeasts, morels, and

truffles

Fungus’ Roles in Nature

EnvironmentalRecycling

Disease - Fighting

Fungus-Plant Root

Association

Disease-Causing

Food

Environmental Recycling

•Many are decomposers

Fungi and Food

•Yeasts help to make bread•We eat mushrooms and truffles

Disease – FightingFungi

•Penicillium produces a substance that kills bacteria

Disease – Causing Fungi•Many are parasites•Corn smut and wheat rust destroyed crops•Athlete’s Foot•Ring worms

Fungus-Plant Root Association

•Symbiotic relationship in which hyphae from a fungus absorbs food and water for the plant

Lichens•Symbiotic relationship between a fungus and either a bacteria or algae.•Useful indicators of pollution because they are very sensitive and die as pollution levels increase