Biology 1001A Lecture Notes - Lecture 9: Antibody, Catastrophism, Cyanobacteria
Cycle 01 Outcomes
Pre-lecture 02 Outcomes
On multiple choice exams, you should be able to identify...
1. Characteristics of viruses and why they are not generally onsidered to e alive.
- Viruses are nucleic acids (single-stranded or double-stranded) enclosed by a protein coat (a capsid).
Some viruses have additional features (ex. protein extensions that can detect a host cell) which have
developed as a result of selective pressures.
- Viruses are not considered to be living because:
- They are obligate parasites: They cannot live without a host cell because they need a host cell
to metabolize and reproduce.
- They are ot fudaetally ellular i their struture they do’t hae cellular plasm or other
structures of a typical cell).
2. Why viral infections are usually difficult to treat with drugs, and exceptions to this general
principle.
- Viruses are usually diffiult to treat ith drugs eause i the proess of disruptig a irus’ lifeyle,
the drug can also damage the host cell. (The highly parasitic nature of viruses prevent drugs from being
effective)
- Hoeer, if oktail drugs a target iruses speifi steps attahig of irio to host ell, reerse
transcriptase, integrase, and protease), these drugs can usually treat viral infections.
3. Whether viruses are always pathogenic.
- Although many viruses are pathogenic, not all of them are. For example, bacteriophages prevent
bacteria from overtaking the Earth and cyanobacteria are infected by viruses that continue the
photosynthetic rate of these bacteria.
4. Hypotheses for the evolutionary origin of viruses.
- Viruses predate cells Virus comes fro the priordial gee pool- the pool of RNA that is thought
to have become the first genetic material
- Since viruses need a host cell, they came after cells Are viruses cell-based life that LOST its
independent metabolism or mobile genetic elements of cells (transposons) that GAINED the ability to
enter/exit cells (they left one cell and one to another)
- Note: Do viruses share a common origin or are there many origins of viruses?
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5. Lifecycle of HIV
*Note: After the RNA has been
translated by the ribosome, an
enzyme known as protease
cleaves newly synthesized
polypeptides at the
appropriate places to create a
mature polypeptide.
6. Characteristics of HIV that affect the prospects for drug design and vaccine development.
- HIV is constantly mutating so there cannot be one fixed drug to combat HIV
-
7. The general mechanisms by which vaccines protect against diseases.
- Vaccines contain inactive viruses that are not pathogenic. When the body encounters the active form
of these viral strains, the vaccines have already primed the immune system to recognize specific viral
antigens, so antibodies are readily available to attack the virus.
• Create a ath of eapos for the iue syste, deployed he eeded
• Pre-immunization allows faster attack on disease/virus
• Vaccine pre-trains body to recognize invader (normally takes weeks to build up a way to fight back)
• Penetrate pneucosal barriers; affects immune cells to replicate
• Macrophages capture and display pieces of HIV so the memory cells from the vaccine are activated
after front line troops are affected.
• Memory B cells turn to plasma cells; generate specific antibodies to latch onto HIV to prevent cell
infection
• Killer T cells seek out and kill already infected cells
8. Why developing a vaccine against HIV is relatively challenging, compared to other diseases.
- HIV hides itself in your genome (makes it hard for antibodies to track and locate the virus, so a vaccine
is useless).
- HIV mutates and evolves very quickly (this makes it hard to develop one vaccine for HIV because of the
large genetic variation of this virus).
- HIV attacks the cells that are designed to attack it (WBCs)
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