T2 bacteriophage virus attacking E. coli bacterium
*** diagram handdrawn: ds DNA, ss RNA - sense; ss RNA + sense, ds RNA
Lytic Cycle: Step 3: Synthesis
Host genome:
Genome of virus:
2 main molecule types that must be
produced during synthesis:
--------------------------------------------- and
----------------------------------------------------------
*Drug targets: nucleotide analogue
SEE DNA REVIEW SLIDE POSTED ON
BLACKBOARD
Master strand of DNA:
+ sense strand of RNA:
-sense strand of RNA:
---------------------------------------------------------------------------------------------------------
(SEE
HANDOUT DONE IN CLASS using “Synthesis stage of viral life cycle” review item,
also Fig. 13.13)
[Summarize the Steps of Synthesis
for each genome type below]
- ds DNA genome
-ss DNA genome (not covered
in class, use text)
- sense (non-sense) ssRNA genome
+ sense ssRNA genome
ds RNA genome (not covered
in class, use text)
Lytic Cycle: Step 4: Assembly (Maturation)
*drug target: protease inhibitors
* vital parts are put together
- capsomeres form capsid
- genetic
material in capsid - Enzymes in capsid
- enveloped peplomers go to membrane
Lytic Cycle: Step 5: Release(Lysis)
* Cell releases virus particles
* Cell releases virus particles
Phages: host cell explodes, host cell dies
Naked: host cell explodes
Enveloped:viruses bud out, gain envelope and peplomers
Fig. 13.14
http://www.microbiologyonline.org.uk/about-microbiology/introducing-microbes/viruses
Fig. 13.14
http://www.microbiologyonline.org.uk/about-microbiology/introducing-microbes/viruses
*** Drug: tamiflu prevents budding so the envelope can't form
Lysogenic Life Cycle Fig. 13.11
Step 1 -Attachment (same as lytic)
Step 2 -Penetration (same as lytic)
Step 3 - Incorporation:
Viral genes: join host cell genome (integrase)****integrase inhibitors is a drug target***
Incorporated Virus genes is now called: Provirus (or called prophage)
Some known triggers which activate
expression of viral genes:
- Chemical, physical, emotional trauma, age, hormones, immune system weak, UV radiation, AA arginine, etc.
*drug target: integrase inhibitors
Step 4 – Synthesis
_______________________________________________________________________
[Summarize the Steps of Synthesis
for each genome type below]
+ sense ssRNA genome – retrovirus
(NOTE: see diagram done in class) *drug
target: reverse transcriptase inhibitors
DNA genome – (not covered in class, use
text)
Step 5 - Assembly
Step 6 - Release
*******
Lysogenic Life Cycle
*DNA viruses
*(RNA
viruses) Retroviruses
*** draw on diagram***
Animal Virus options:
Lystic Cycle.... imediate replication with host cell death
Lysogenic cycle (3 options):
- Dormant/latent infection- triggered later
- Persistent infection: continous release- cell lives
- Tumor formation: oncogene activation
Viral connection to cancer:
* Cancer is a result of uncontrolled cellular reproduction
* Proto-oncogene (prexisting) gene converted to oncogene by mutation: at least 2 mutations to change
Figure 13.15
http://www.youtube.com/watch?feature=player_embedded&v=U6QwtBl870I
Specific viruses and cancer:
*Example cancer-causing viruses:
*Example cancer-causing viruses:
- Human papilloma virus = genital warts and cervical cancer
- Hepatitis B and C viruses = liver cancer
- human herpes virus 4= Burkitt's lymphoma (coinfection with malaria)
- human Herpes Virus B = Kaposi's sarcoma (coinfection with HIV-1) purple spots that attack connective tissue
- Loss of tumor suppressor genes
- Normally on- inhibit mitosis in abnormal cells
- Loss of apoptosis
- Normally on - cause abnormal cells to commit suicide
- Example p53 tumor suppressor.... picture..of development of figure and toes that use apoptosis to divide them, example of child who have two fused fingers instead of seperating
- Angiogenesis
- Normally off - growth of new blood vessels into mass of new cells
- What is Tumor Angiogenesis? picture: small localized tumor.... angiogenesis causes tumor that can grow and reproduce becuse new blood vessels to bring nutrients
- Metastasis
- normally off- separation and spread of cells
