Biology 1001A Lecture Notes - Lecture 1: Reverse Transcriptase, Viral Phenomenon, Dna Replication
13 Jun 2018
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Test Review - Cycles 1 - Viruses & HIV
Characteristics of Viruses
- not considered to be living
- do not have metabolic processes, tf no energy cycles
- Obligate Parasite: cannot reproduce on their own, depend on the host to survive
- do not have a cell structure with organelles
- 1/more nucleic acid molecules surrounded by a coat/capsid
- capsid may be enclosed by a membrane or envelope (envelope comes from host)
- can have DNA or RNA, tf double or single stranded
- helical or polyhedral
Why Viral Infections are Hard to Treat?
- antiviral drugs have worse side effects than antibacterials, antifungals
- because viruses are reliant on host, that there are almost on steps that can kill the virus
without killing the host
Non-Pathogenic Viruses
- protective viruses interfere with the replication of pathogenic viruses
- bacteria is destroyed by viruses called bacteriophages
- they affect nutrient cycling through their effects on prokaryotic organisms
Evolutionary Origins of Viruses
1. evolved after cells… could be escaped DNA from a living cell or RNA fragment, fragments
became surrounded by protein layer with recognition functions, as viruses evolved the
information encoded became directions to produce more viruses. because viruses can
reproduce in a host cell
2. primordial gene pool - pool of RNA thought to be 1st genetic material
- no common ancestor for all viruses, different viruses have different genetic material
Lifecycle of HIV
1. the glycoproteins of the virus attaches to the protein receptors on the plasma membrane of
the host cell, viral content is release inside the cell
2. reverse transcriptase catalyzes the formation of double-stranded DNA from viral RNA
3. Viral DNA gets integrated into the host chromosome
4. the DNA copy of the viral genome is translated & transcribed to produce mRNA and proteins
- this mRNA is used as a genome for new viruses
5. the mRNA and proteins bud out from the cell
- T-cells cause the membrane to rupture as they exit causing the cell to die
- macrophages bud out of the cell
Characteristics of HIV that effect vaccine development
- HIV mutates quickly and extensively, because Reverse Transcriptase does not have
proofreading abilities… tf lots of mistakes
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Test review - cycles 1 - viruses & hiv. Do not have metabolic processes, tf no energy cycles. Obligate parasite: cannot reproduce on their own, depend on the host to survive. Do not have a cell structure with organelles. 1/more nucleic acid molecules surrounded by a coat/capsid. Capsid may be enclosed by a membrane or envelope (envelope comes from host) Can have dna or rna, tf double or single stranded. Antiviral drugs have worse side effects than antibacterials, antifungals. Because viruses are reliant on host, that there are almost on steps that can kill the virus without killing the host. (cid:1688)protective(cid:1689) viruses interfere with the replication of pathogenic viruses. Bacteria is destroyed by viruses called bacteriophages. They affect nutrient cycling through their effects on prokaryotic organisms. No common ancestor for all viruses, different viruses have different genetic material. This mrna is used as a genome for new viruses: the mrna and proteins bud out from the cell.
