Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
31 Cards in this Set
- Front
- Back
|
Distinction between obligates and fcultative?
|
Obligates require a host to live, faculative do not.
|
|
|
Three broad groups of pathogens?
|
Viruses, bacterial pathogens, and eukaryotic parasites.
|
|
|
What are viruses? Are they alive? What do they lack (4)?
|
NO!!! They are obligates. Require a host to survive.
They lack 4 essential things for life: They lack an ability to take up energy & make use of it They lack an ability to transport themselves They lack an ability to reproduce themselves They lack any metabolic abilities or functions |
|
|
Can you use antibiotics against viruses?
|
No, of course not, because the virus is invading and using the host, so you'll just be damaging the host. Antibiotics only work on bacterias and infectious eukaryiotic.
|
|
|
What is a capsid?
|
Protein sheath that protects the virus... some may have this.
|
|
|
What else might viruses contain?
|
genetic material, capsids, envelopes and possible enyzmes.
|
|
|
How viruses store their genetic material?
|
single stranded DNA
single stranded RNA double stranded RNA Never stored as double stranded DNA. Therefore, they likely require special viral enyzmes to replicate and read this information. |
|
|
Virion? What can they do (2)?
|
An infectious virus particle. They have the necessary information to:
(1) gain entry into a host cell (2) have the virus genome replicated and transcribed This may include bringing in some virus specific enzymes |
|
|
Why would natural selection favor a virus that doesn't kill the host?
|
Because it's an obligate, and NEEDS the host cell to live, reproduce and doing anything. Thus, a virus that can keep the host alive so it can be passed on would likely be selected for.
This explains the myoxma virus, and why it became LESS deadly overtime. The strands that were being passed on, where the ones that weren't fully killing their hosts. The ones that killed the hosts, weren't able to be passed on! |
|
|
When does it not matter if a virus kills the host cell?
e.g.,? |
If it can invade multiple species.
Like rabies (neurotropic virus)! That shit gets passed on easily through saliva in a bite. It causes the animal to become rabid, which then causes it to bite someone/something and pass on the virus. |
|
|
Ebola virus and "emerging" viruses?
|
Ebola virus is a hemmoragic virus.
Cultural habits (hunting primates, rinsing the dead) caused the virus to jump the species barrier between primates and humans, and infected a whole village. |
|
|
zoonotic diseases?
|
Those that jump from animals to humans.
This was radically increased when we started having livestock 15, 000 years ago. |
|
|
Tissue/host ranges for: Rabies, swine flu, HIV.
Reservoirs? |
Rabies -- raccons, foxes, skunks, dogs, humans, etc.
swine flu -- pigs and humans HIV -- two types of human white blood cells Reservoirs -- ducks pigs and chickens are reservoirs (they aren't affected by the virus, but hold on to it) for the human influzenza. |
|
|
Viruses have to enter the cell, and they can't enter all types of cells. When can they best jump species barriers?
|
(1) The species are closely related
(2) There is prolonged contact between two species |
|
|
How does rabies enter the cell?
|
Endocytosis
|
|
|
How can the virus use the cell's membrane to its advantage?
|
Enters the cell by fusing with, replicates itself, and then pinches off a new portion of the cell membrane for the envelope of the new viruses.
|
|
|
What's unique about HIV?
|
uses RNA as a genome... has to be reverse transcribed into DNA, using is own enzyme reverse transcriptase. Eventually becomes double stranded DNA. Two fates:
(1) Start viral replication (2) Or viral DNA integrates into the host genome. Becomes a Provirus. |
|
|
Provirus?
|
Provirus can remain unused or can be activated to start viral replication.
|
|
|
What class of viruses does HIV belong to?
|
Retrovirsues -- many of which are innocuous.
|
|
|
Why does HIV become so devastating when it becomes full blown AIDS?
|
It targets cells in the immune system, and so the very things it needs to clear the virus, are now damaged.
|
|
|
How does dengue enter the cell?
|
– protein in the virus causes the host cell shapes to change and fuse with the virion (due to ph changes). Doesn’t require additional input of energy. Now there is a direct channel into the host cell.
|
|
|
2 possible life cycles for bacteriophage?
|
Lytic cycle - virus being reproduced - leads to cell death
Lysogenic cycle - viral DNA incorporated into host cell DNA. Becomes a provirus. Can eventually go to the other side, and start being reproduced. |
|
|
Transduction?
|
The way the bacteria gets new genetic information. Since they reproduce asexually, there is a limited amount of genetic material. Bacteriophage can help bacteria if they accidentally transfer DNA
among individual cells causing an exchange of genetic information |
|
|
Three ways that bacterias get new DNA (transduction is one of em)?
|
(1) transduction
(2) Transformation -- uptake of free DNA (3) Conjugation -- transferring of DNA via sex pillius. |
|
|
Do different bacterias use different modes of plasmid transfer?
|
yes, and each have a preferred mode.
e.g., plagues and streptococcus (flesh eating) use conjugation gonnorhea uses transformation Staphylococcou (toxic shock syndrome) uses transduction |
|
|
What's the double edged sword of antibiotics development?
|
Takes 400-800 million dollars to develop, and can take 10-20 years to get approved.
Thus, natural solutions are the best. |
|
|
Fimbriae and the slime layer are for bactera ?
|
Virulence factors... they allows the pathogen to invade the host, obtain nutrients from the host, etc.
|
|
|
What are Encephalopathies?
|
IN head sufferings. Spongy brain diseases like prions.
|
|
|
Four examples of prion diseases?
|
Mad cow, scrappie (in sheep), chronic wasting disease (in wildlife... big problem), Kuru and CJD (Kuru is due to cultural habits of cannablism... infection spreads from eating the raw meat of others with the disease).
|
|
|
What is unique about prions?
|
Disease transformation without genetic information. One misfolded protein comes into contact with a properly folded one, and there is a domino effect. With enough midfolds, it start interfering with nerve transmissions.
|
|
|
How did the original mad cow prions disease happen?
|
Feeding the cows their dead friends' brains... led to the transmission of the disease very rapidly.
|
