Viruses, Bacteria

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Viruses, Bacteria Diseases

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Viruses

• Viruses are NOT cells. A virus is an infectious
  agent made up of
• a core of nucleic acid (RNA or DNA)
• a protein coat (capsid)
• Genetic material carries information for
  multiplication
• Hijacks biochemical machinery of host
• cell to carry these processes out
• Soviruses are NOT LIVING

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Characteristics of life
CELL VIRUS
Made of cells YES NO
Obtain use energy YES NO
Grow develop YES Only inside a living cell
Reproduce YES Only inside a living cell
Respond adapt YES YES
Contain RNA or DNA YES YES
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Re-Cap

• Viruses are NOT ALIVE. Viruses do not
• Grow
• Have homeostasis
• Metabolize
• Viruses do
• Infect cells and use the cell to make more
  viruses
• Cause disease in many organisms

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Structureof a virus
ENVELOPE

• Envelope (part of the protein coat)
• Capsid (part of the protein coat)
• Nucleic acid (either DNA or RNA)

NUCLEIC ACID
CAPSID
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Retrovirus
CAPSID

• A virus that contains RNA instead of DNA
• Human Immunodeficiency Virus (HIV) is a
  retrovirus
• HIV causes AIDS

ENVELOPE
RNA
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Bacteriophage

• A virus that only infects bacteria

CAPSID
HEAD
DNA
CAPSID
TAIL FIBER
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Ticking time bombs . . .
Viruses do not reproduce by themselves. They
invade a living cell and let the cell do the work
for them.
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Lytic Cycle
The viral infection that rapidly kills the host
cell is the lytic cycle.
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Cycle Illustration
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Lysogenic Cycle
The viral infection that enters a cell, remains
harmless for a period of time (sometimes years),
and then becomes harmful later is called the
lysogenic cycle.
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Lysogenic Cycle
In the lysogenic cycle, the virus reproduces by
first injecting its genetic material, indicated
by the red line, into the host cell's genetic
instructions.
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Role of viruses

• All viruses act like parasites, harming the host
  cell.
• Viruses cause disease in every kind of
  organismanimals, plants, fungi, protists, and
  bacteria.

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Some viral diseases

• HIV
• Measles
• Smallpox
• Influenza
• Chicken pox

• Common cold
• Herpes
• Warts
• Mononucleosis
• Mumps

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HIV

• A retrovirus
• Infects human helper T-cells, which are
  associated with the immune system.
• Modes of transmission
• Sexual contact with an infected person
• Sharing needles with an infected person
• Blood transfusions (rare)
• Breast feeding
• Etc.

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HPV

• Human Papilloma Virus
• Causes warts
• Most common STD in the United States
• 80 of women by the age of 50 will have acquired
  some strain of genital HPV.
• HPV vaccine

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Influenza (flu)

• Symptoms body aches, fever, coughing, runny
  nose, fatigue, usually lasting about a week.
• Mode of transmission
• Airborne (air droplets)
• People still die from influenza.

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Viral diseases

• usually cannot be cured, but many can be
  prevented by
• Good hygiene

• Immunization

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Bacteria

• Bacteria are Prokaryotes. Prokaryotic Cells
• Have no nucleus
• Do not have membrane bound organelles
• Are very small
• Often have a flagellum for movement

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Shapes of bacteria

• Bacteria are classified according to their shape
• Round is called cocci
• Rod shaped is called bacilla
• Spiral shaped is called spirilla

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Where do they live?

• Bacteria are found in all environments

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Role of bacteria

• Some bacteria are helpful
• E. coli
• Yeast
• V.streptococci
• Lactobacillus
• Some bacteria are harmful
• E. coli
• S. pyogenes
• S. aureus
• Y. pestis

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Streptococcus

• Causes strep throat, pneumonia, and other
  infections.
• Named based on the shape and orientation of the
  bacteria.

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Staphylococcus

• Cause of staph infections that occur on the skin
  or in wounds. (ex. MRSA)
• But, Certain types of staph reside normally on
  the skin.

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Diphtheria

• Swelling of the upper respiratory tract
• DPT Vaccine
• Can also infect skin cells.

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• How do bacteria cause disease?
• The release toxins that interfere with normal
  activity.

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Prevention/Cure

• Vaccines to prevent.
• Antibiotics to cure (pennicillin, amoxycillin,
  etc).