VIRUSES

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VIRUSES Alive or Not?
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RECALL The SIX Characteristics of Life

• Made up of cells
• Made up of similar chemicals
• Uses energy
• Grows and develops
• Responds to the world around them
• Reproduces

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WHAT IS A VIRUS?

• Virus small, nonliving particle that invades
  and then multiplies inside a living cell.
• Do not use energy to grow or to respond to their
  surroundings
• Cannot make food, take in food, or produce wastes

The common cold virus - Rhinovirus
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Virus Shapes and Sizes

• Vary in shape and size
• Round
• Rod-like
• Robot-like
• Brick shaped
• Although they vary in size, all viruses are
  extremely tiny. The largest virus is no more
  than 250 nm long.
• Whats a nanometer?

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Virus Structure

• Protein Coat
• - each virus has unique proteins on its coat,
  the shape of the proteins determine which cells
  it will attack.
• 2. Genetic Material
• - Either DNA or RNA

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Viruses Can Only Multiply When They are Inside a
Living Cell

• Viruses act like a parasite because they destroy
  the host cells they take over when they multiply.

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Two Types of Viruses

• Once a virus enters the cell it takes over the
  cells functions.
• Some viruses take over right away, others wait a
  while.
• Active virus
• Hidden virus

Examples of each kind Hidden HIV,
herpes Active Rhinovirus, Influenza, Chicken
pox
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How Do Viruses Multiply?

• STEP ONE
• ABSORPTION
• The virus attaches itself to the cell membrane

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How Do Viruses Multiply?

• STEP TWO
• ENTRY
• The virus injects its genetic material.

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How Do Viruses Multiply?

• STEP THREE
• REPLICATION
• The cell starts to produce the viruss proteins
  and genetic material.

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How Do Viruses Multiply?

• STEP FOUR
• ASSEMBLY
• New viruses assemble.

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How Do Viruses Multiply?

• STEP FIVE
• RELEASE
• The cell bursts open releasing new viruses.

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Hidden Viruses Multiply Differently

• The only difference is that the hidden virus
  genetic material becomes a part of the organism
  for a while until it becomes active.
• See the difference here.
• Cep-1021

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REMEMBER THE STEPS

• ABSORPTION
• ENTRY
• REPLICATION
• ASSEMBLY
• RELEASE

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Viral Diseases

• Can cause some short-term sickness (Ex. Common
  cold)
• Can cause death (Ex. AIDS)
• Spread through physical contact or inhaled
  droplets
• NO medications to cure viruses.
• medicines can treat the symptoms
• Our immune system (white blood cells) is our
  first defense

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Preventing Viruses

• Vaccines substance that stimulates the body to
  produce chemicals that destroy viruses or
  bacteria.
• - may be dead or altered viruses
• - they activate the bodys natural defenses

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How are Antibiotics and Vaccines Different?

• ANTIBIOTICS
• A chemical used to kill or slow the growth of
  bacteria

• VACCINES
• Virus introduced into the body in order to put
  the body on alert. If the virus ever infects
  the body, the immune system recognizes it and
  destroys it.

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Why get a Vaccine?

• How are vaccines beneficial?
• Besides vaccines, what other methods should be
  used to help prevent disease?
• Why do people still get the flu even though
  theyve gotten the flu shot?
• Why not just get a SUPER Flu shot that covers
  them all?

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EXAMPLES OF VIRUSES

• Polio
• Small pox
• Human Papillomavirus
• AIDS
• Influenza
• Herpes

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How Viruses Effect Humans

• HPV
• More than 100 different strands
• Transmitted by direct contact
• Symptoms Warts or none
• Very extreme case
• Tree man

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• Measles A Case Study
• Symptoms Measles symptoms usually show up in
  two stages.
• Stage 1 runny nose, cough, and a slight fever.
  As the infection progresses, the person's eyes
  become red and sensitive to light, and the fever
  rises.
• Stage 2 (3-7 days later) The fever reaches
  103oF-105oF, and a red blotchy rash appears. The
  rash usually starts on the face and then spreads
  to the chest, back, and arms and legs,.The rash
  lasts for 4 to 7 days. Small white spots might
  also appear on the gums and inside of the cheeks.
• Measles is very contagious. An uninfected person
  can get measles simply by breathing the air in a
  room where an infected person has been.
• The virus can live in the air for 2 hours after
  an infected person leaves a room. Infected
  persons are usually infectious to others even
  before symptoms appear. (hidden virus)
• Complications Pneumonia occurs in up to 6
  percent of reported measles cases and accounts
  for 60 percent of deaths from measles.
  Encephalitis (inflammation of the brain) can also
  occur.
• Infants under age 2 years and adults over age 20
  have a greater risk of complications.
• Prevention Get vaccinated!
• Not so easy for some.