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Viruses & Bacteria

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A)Students will derive the relationship between single-celled and multi-celled organisms and the increasing complexity of systems.

B) Compare how structures and function vary between the six kingdoms.

C) Examine the evolutionary basis of modern classification systems.

d) Compare and contrast viruses with living organisms.

UNIT GOALS

A virus is a nonliving particle with a simple structure. Composed of a nucleic acid (DNA or RNA) surrounded by a protein coat.

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Capsid - The capsid is the protein shell that encloses the nucleic acid; Three functions:

1) it protects the nucleic acid from digestion by enzymes, 2) contains special sites on its surface that allow the virus to attach to a host cell, and 3) Allow virus nucleic acid penetrate the host cell’s membrane and, in some cases, to inject the infectious nucleic acid into the cell's cytoplasm.

Envelope - Surrounds the capsid. Composed of two lipid layers interspersed with protein molecules

Or

RNA

Or

RNA

Virus Structure

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Viral Nucleic Acid •The nucleic acid of each virus encodes the genetic information for the synthesis of all proteins. •Only a few groups of viruses use DNA. •Most viruses maintain all their genetic information with the single-stranded RNA.

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Viruses, such as the influenza virus, that have RNA as their genetic material mutate more often that DNA viruses.

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1.The virus attaches to a host cell and injects its nucleic acid into the cell.

2.The viral nucleic acid is immediately replicated, eventually causing the host cell to burst, releasing new viral particles.

3.These new viruses then attack other cells.

Lytic Cycle

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Animation

Lysogenic Cycle After the virus embeds its nucleic acid into the chromosome of the host cell, the viral nucleic acid is replicated along with the host cell’s DNA. Then the virus becomes dormant, sometimes for years without the host knowing. The virus may suddenly become active, resuming the lytic cycle, which will eventually destroy the host cell. 8

Animation

Overview: Lytic and Lysogenic cycles

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Are viruses alive?

• Can They: – Reproduce?

– Obtain and use energy?

– Grow, develop, and die?

– Respond to the environment?

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Do they meet the

criteria for life?

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Vaccines

13 Clip on next slide

EXTRAS

• Prion-is a type of infectious agent made only of

protein.

• Chronic wasting disease, (in deer and elk), mad

cow disease

• All of these diseases affect the structure of the

brain or other neural tissue, and all are

untreatable and fatal.

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Viroids • small naked single-stranded

RNA molecules that infect plant cells and cause disease.

• Smaller than viruses, viroids are not enclosed in a protein coat of any kind.

• They generally consist of less than 400 nucleotides and do not contain any genes.

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Compare and contrast viruses with living organisms.

Examples to include:

-Mode of nutrition? -Characteristics of living things -Reproduction -Structure -Homeostasis? - Cell structures?

Viruses 6 kingdoms of

Living things

Diseases Caused by Viruses

Influenza

1918 pandemic 20 to 40 million people

More people died of influenza in a single year than in four-years of the Black Death Bubonic Plague from 1347 to 1351. Known as "Spanish Flu" or "La Grippe" the influenza of 1918-1919 was a global disaster

Polio • Polio is a contagious, historically devastating

disease that was virtually eliminated from the Western hemisphere in the second half of the twentieth century. Although polio has plagued humans since ancient times, its most extensive outbreak occurred in the first half of the 1900s before the vaccination, created by Jonas Salk, became widely available in 1955.

• People who have abortive polio or nonparalytic polio usually make a full recovery. However, paralytic polio, as its name implies, causes muscle paralysis - and can even result in death. In paralytic polio, the virus leaves the intestinal tract and enters the bloodstream, attacking the nerves (in abortive or asymptomatic polio, the virus usually just stays in the intestinal tract). The virus may affect the nerves governing the muscles in the limbs and the muscles necessary for breathing, causing respiratory difficulty and paralysis of the arms and legs. Although the acute illness usually lasts less than 2 weeks, damage to the nerves could last a lifetime.

•What's the Future of Polio? Through intensive vaccination programs, a coalition of organizations in 1999 decided to work toward world eradication of polio by 2005. Between 1988 and 1998, wild-type polio was eliminated from North America, South America, and Europe. But polio still exists in Africa, as well as India and some of its neighboring countries.

People can be exposed to Ebola virus from direct contact with the blood and/or secretions of an infected person: contact with objects, such as needles, that have been contaminated with infected secretions

Human Immunodeficiency Virus

Lassa Fever

The number of Lassa virus infections per year in West Africa is

estimated at 100,000 to 300,000, with approximately 5,000 deaths. In

some areas of Sierra Leone and Liberia, it is known that 10%-16% of

people admitted to hospitals have Lassa fever, which indicates the

serious impact of the disease on the population of this region.

Chickenpox

• Chickenpox is a very contagious viral disease that causes an itchy outbreak of skin blisters.

• The chickenpox virus spreads from person to person by direct contact with fluid from broken chickenpox blisters.

• Chickenpox is usually a mild disease. However, in adults and children with weakened immune systems, chickenpox can cause serious complications and even death.

• A vaccine is now available to prevent chickenpox.

Hantavirus

Measles • Diseases of childhood that causes a skin rash. • Serious complications, such as pneumonia, croup or

encephalitis, can occur. • The disease starts with a cold, fever, cough,

conjunctivitis (red eye) and fatigue. Three days later, a red blotchy rash starts on the face - then spreads to the rest of the body, including the feet. The fever starts to go down on the second or third day of the rash. There may be some fine peeling of the skin after the rash fades. Most patients are ill for about seven days;

• IS IT CONTAGIOUS? VERY. It is most common in late winter and early spring. Most people have been exposed to the disease 10-12 days before they have any symptoms. Spread by coming in contact with the saliva of someone who has the disease through coughing, kissing or sharing of eating utensils.

• Once you have had a case of measles you have lifetime immunity (protection) to the disease.

Mumps

Rabies

Most often transmitted through the bite of a rabid animal

Smallpox • Infection usually occurred by inhalation of

virus • acute, with fever, malaise (discomfort/out of

sorts), headaches, and backaches. The initial toxemia phase lasted 4-5 days. On about the third or fourth day, the characteristic rash appeared. First, it appeared on the buccal (mouth) and pharyngeal (throat) mucosa, the face, and the forearms. Within a day, it spread to the trunk and lower limbs.

• The lesions usually protruded from the skin and are firm to touch. About 8 weeks after onset of the rash, the lesions dried up and became crusted by day 14. By the end of the third week, most crusts had fallen off, with the exception of the palms and the soles. The outcome of infection was either death or recovery with immunity.

In 1966, the World Health Organization started a program for the worldwide eradication of smallpox. Through intensive case finding and vaccination of direct and indirect contacts, the disease was finally eradicated on December 9,1979.

Hepatitis Hepatitis is a disease that impairs liver function either temporarily or permanently, sometimes even leading to death. It can be initiated by a host of factors, but primarily by viruses. Drugs also can cause hepatitis but when the specific drug is discontinued, the liver usually returns to normal.

Hepatitis B This type is essentially a blood-borne virus with other bodily fluids being infectious, notably semen and saliva, and is often transmitted from mother to fetus.

Hepatitis C Before a blood test was discovered in 1989 to screen for HCV, this was the most frequent hepatitis to be acquired from blood transfusions and blood products. Up to half of those with chronic disease will go on to develop liver failure and need a transplant. Each year, 8,000 to 10,000 people die in the United States because of hepatitis C-related cirrhosis or HCV-related liver cancer.

Herpes

• Infection caused by the Herpes Simplex Virus (HSV), which resides in the nerve ganglia after the initial exposure to the virus.

• Because the virus is so effective at "hiding out" in the nerve cells, the body is never able to eliminate the herpes virus completely. Instead, after the initial infection, the body produces antibodies which show up in the blood stream.

• Blood tests which indicates the presence or lack of these antibodies.

• The antibodies make it easier for the body to recognize and attack the virus when it re-emerges from the nerve cells in the form of an outbreak.

• For this reason, out breaks following the primary outbreak usually diminish in frequency and intensity over time.

• Some people may never have another outbreak.

Retrovirus

• Has an RNA genome that is converted to DNA in the host cell

• HIV

• Reverse transcription ANIMATION

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MONERA

EUBACTERIA ARCHAEABACTERIA

1.Largest 2.Unicellular 3.Prokaryotic 4.Most use oxygen but some are anaerobic.

1.Unicellular 2.Prokaryotic 3.Ancestors of Eukaryotes 4. Lives in harsh environments.

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Round

Rod Spiral

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Flagella

Cell membrane

Ribosome Pili

Plasmids

Chromosome

Cell Wall

Method scientist use to determine cell wall type in

bacteria

Gram Staining

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Nutrition

-obtaining energy

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Releasing Energy

Obligate Aerobes

Facultative Anaerobes

Obligate Anaerobes

Must Have Oxygen

With or Without Oxygen

Cannot Have Oxygen

9.1

Take in “food” and Eliminate Waste

• Take in “food” by endocytosis

• Eliminate waste through the cell membrane by exocytosis.

9.2

Bacteria Reproduction

Sexual Asexual

Conjugation Binary Fission

Exchange DNA Split 10

E. coli undergoing conjugation

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Endospores are a method of survival. 14

ENDOSPORE FORMATION

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BACTERIA HELPFUL HARMFUL

Soil---decomposing

Plants---nitrogen fixation

Humans---digestive system

Humans---Food:cheese, yogurt, sauerkraut, &

soy sauce.

Diseases

Photosynthesis produces oxygen

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Humans---Genetic

Engineering

Diseases caused by Bacteria

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Bacterial Diseases

release poisons

that Harm

the body

breaking down

Tissues for

food

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Treatments –Vaccines

»Before infection

–Antibiotics »After infection

Alexander Fleming

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antibiotics can be

used to destroy

bacterial cells

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Different ways to prevent a

bacterial infection. 1) Sterilization:

Uses heat or chemicals to kill

bacteria from objects.

2. Skin and surfaces that have been in contact with raw meat should be washed thoroughly, food should be cooked properly, and contaminated water should be boiled.

2. Avoid contact with an infected organism or organisms that carry

disease-causing microorganisms. • Plague swept across Europe in the Middle Ages, half of the

population died. • Bacteria transmitted through the bite of a flea.

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Why do we refrigerate our food?

• Slows down the

growth of bacteria.

– Slows down spoilage.

EOCT

QUESTIONS

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The outer layer of a virus is

made of A) carbohydrates B) lipids C) nucleic acids D) proteins

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A vaccinations B blood transfusions C vitamin C D antibiotics

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A bacteria

B fungi

C protozoa

D viruses

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Why is food preserved by canning in glass

containers normally safe for later

consumption?

A The glass allows solar radiation to kill the bacteria that were in the food. B Bacteria are destroyed by extreme heat in the glass container. C Bacteria are removed from the food before it is placed in the glass container. D The glass container prevents oxygen.

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• Microorganisms such as bacteria are able to change and adapt much more quickly than other organisms.

• Bacterial populations, for example, are able to build a resistance to antibiotics within months, whereas compounds that are toxic to animals remain toxic to animals for many years.

• One reason for their rapid adaptability is that microorganisms

A are highly motile B have a short life span C have specialized organelles D are chemosynthetic

Recognize the

role of

evolution to

biological

resistance