Transcript Glencoe Biology

What do you know about Viruses?
• 1. What are the 5 most common viral
infections?
• 2. Name 2 similarities between a virus and a
bacteria?
• 3. Name 2 differences between a virus and
bacteria.
????
Top 7 most common viral diseases
identified by CDC
•
•
•
•
•
•
•
1. Avian flu
2. Influenza
3. Genital Herpes
4. Hepatitis
5. Cervical cancer (Humanpapilloma virus)
6. Meningitis
7. HINI flu
FACTS
• 1. There are a million virus particles per
milliliter of seawater – for a global total of
1030 virions! Lined up end to end, they would
stretch 200 million light years into space.
• 2. Walter Reed discovered the first human
virus, yellow fever virus, in 1901.
• 3. Over 1016 human immunodeficiency virus
genomes are produced daily on the entire
planet. As a consequence, thousands of viral
mutants arise by chance every day that are
resistant to every combination of antiviral
compounds in use or in development
• 4. The first human influenza virus was
isolated in 1933. In 2005, the 1918 pandemic
influenza virus strain was constructed from
nucleic acid sequence obtained from victims
of the disease.
• 5.The biggest known viruses are
mimiviruses, which are 400 nanometers
(0.0004 millimeters) in diameter. The viral
genome is 1,200,000 nucleotides in length
and codes for over 900 proteins.
• 6. The smallest known viruses are
circoviruses, which are 20 nanometers
(0.00002 millimeters) in diameter. The viral
genome is 1,700 nucleotides in length and
codes for two proteins.
Virus: General characteristics
 A strand of genetic material within a protein
capsid.
 Has a tail for attachment
 Lacks cell /organelles
 Cannot make proteins
 Cannot move
 Cannot replicate on their own
 Most viruses range in size from 5 to 300
nanometers.
Virus Origin
 Viruses came from parts of cells.
 Genetic material of viruses is similar
to cellular genes.
Lytic Cycle
 The host cell makes many copies of the
viral RNA or DNA. Virus is assembled,
destroys cell and gets out.
Lysogenic Cycle (hidden cycle)
 Viral DNA inserts, or integrates into a
chromosome in a host cell.
 Infected cell will have the viral genes
permanently.
Chapter 18 Bacteria and Viruses
18.2 Viruses and Prions
Chapter 1
Bacteria and Viruses
Prions
 Protein that can cause infection or disease
is called a proteinaceous infectious particle,
or prion.
 Prions normally exist in cells.
 Associated with diseases known as
transmissible spongiform encephalopathies
Smallpox has been
eliminated worldwide
and routine vaccination
for the disease has
stopped.
A. True
B. False
1. A
2. B
What type of virus inserts RNA and reverse
transcriptase into cells?
A. adenovirus
B. bacteriophage
C. prion
D. retrovirus
1.
2.
3.
4.
A
B
C
D
For which virus is there not yet a vaccine?
A. HIV
B. polio
C. rabies
D. smallpox
1.
2.
3.
4.
A
B
C
D
What type of infection is caused by a virus
that replicates by the lysogenic cycle?
A. active infection
B. passive infection
C. advanced infection
D. latent infection
1.
2.
3.
4.
A
B
C
D
Animation
 Visualizing Viral Replication
 Retrovirus Replication
Retroviruses
 Viruses that have RNA instead of DNA for
their genetic material
 Retroviruses have a protein capsid.
 Lipid envelope is obtained from the plasma
membrane of a host cell