Transcript Class 3 symbiosis

“Chance favors the prepared mind.”
Louis Pasteur
 SYMBIOSIS
◦ NEUTRALISM
◦ COMMENSUALISM
◦ MUTUALISM
◦ PARASITISM




Def: living together or close association of
two dissimilar organisms; usually different
species
Beneficial to both species
Marriage would have been a good example
but we are not different species. 
Just from different planets….



Neither symbiont benefits from the
relationship.
They live in the same space but do not notice
each other.
Sort-of like polite but soon to be divorced
parents.


The microorganism benefits from the
relationship but not the host.
When the indigenous flora remains in its
usual place, the host is not harmed but the
microorganism lives.




Mutual benefits to microorganism and host
E. Coli benefits from the nutrients in the
bowel of the host. The host benefits from the
production of Vitamin K by the E. coli.
Lichen is an algae and a fungus living
together on a rock.
Must live together to survive.



Beneficial to the parasite at the cost of the
host.
A smart parasite does not harm the host but
only takes the nutrients it needs – like an
orchid on a tree.
A “dumb” parasite causes a disease in the
host which can make the host die; so will the
parasite.





Chemotherapy is not only to treat cancer.
The use of any drug is a chemotherapeutic
use.
Started with bark, herbs and teas; moved on
to mercury and arsenic
1940’s penicillin (Andrew Fleming) was
discovered from mold.
Other antibiotics come from bacteria. Many
drugs have been synthesized from E. coli

1. Type of genetic material
◦ DNA or RNA








2.
3.
4.
5.
6.
7.
8.
9.
Shape of the capsid (protein coat)
Number of capsomeres (small protein units)
Size of the capsid
Presence or absence of an envelope
Type of host it infects
Type of disease it produces
Target cell
Immunologic or antigenic properties





Possess either DNA or RNA
Unable to replicate on own
Do not divide by binary fission, mitosis or
meiosis
Lack genes and enzymes necessary for
energy production
Use host cell’s ingredients for protein and
nucleic acid production



Contact can be airborne or contact
Virus settles into/ onto the body and enters
an open portal.
*Virus attaches to cell membrane, injects
nucleic acids, “cons” cell’s DNA into
synthesizing the new material. New viruses
are made until the cell bursts, sending more
viral material into the interstitial space.
Repeat from *; repeat from *, repeat from *,
repeat from * etc

Virulent = Lytic cycle
◦
◦
◦
◦
◦

Attachment
Penetration
Biosynthesis
Assembly
Release
Temperate
◦ DNA remains integrated with bacterial cell’s
chromosomes, generation after generation; this is
one way bacteria acquire new genetic information




Epstein-Barr virus = nasopharyngeal cancer,
Burkitt’s lymphoma, B cell lymphoma
Herpesvirus 8 = Karposi’s sarcoma
Hepatitis B & C = liver cancer
Human papillomavirus = cervical cancer


Papillomavirus – Warts
Polyomavirus – some tumors; some cancers





Herpes Simplex 1 – Cold sores or fever
blisters
Herpes Simplex 2 – Genital herpes
Herpervirus 8 – Kaposi’s sarcoma
Herpes zoster – Shingles
Varicella - Chicken pox
 Respiratory
infections,
pneumonia, conjunctivitis,
some tumors




Rhinovirus – Colds
Poliovirus – Poliomyelitis
Hepatitis types A and B – Hepatitis
Coxsackievirus – respiratory infections,
meningitis




Orthomyxoviruses types A and B – Influenza
Myxovirus parotidis – Mumps
Paramyxovirus – Measles (rubeola)
Rhabdovirus - Rabies



HIV (main one of this generation) – AIDS
HTLV virus (RNA) – Leukemia
RNA tumor virus - Tumors



Theory 1 - They were around before cells
Theory 2 – They came after cells and are
made of fragments of cellular materials
What do you think?