Lecture 6: Structure of viruses Flashcards
What is a virus?
A small nucleic acid genome enclosed in a protein capsid and sometimes a membranous viral envelope.
The protein enclosing the viral genome is called?
Capsid
A Capsid is built from large num of protein subunits called?
Capsomers
What is a viral envelope?
Envelopes are derived from membranes of host cell - contain host cell phospholipids & membrane proteins. Envelopes enclose the capsid.
What are viroids?
Are circular naked RNA molecules that infect plants and disrupt their growth.
What are prions?
Are slow acting, virtually indestructible infectious proteins that cause degenerate brain disease in mammals. Converts normal cells into abnormal cells - into prions
Phages (viruses that infect bacteria) can replicate by two mechanisms:
The lytic & lysogenic cycle
What is the lytic cycle?
Replicative cycle that causes destruction of host DNA, production of new phages & lysis(death) of host cell releases phages
What is the lysogenic cycle?
Is when genome integrates into bacterial chromosome as a prophage which is 1) is replicated and passed onto daughter cells 2) can be induced to leave chromosome and initiate a lytic cycle.
The cold sore viral is and example of:
Viral latency as it remains dormant in the near gangolion as a lysogenic virus
What is the function of reverse transcriptase in retroviruses?
Uses viral RNA as a template for DNA synthesis
What is the major difference a DNA virus & a RNA virus?
RNA virus integrates into the genome
DNA does not integrate
Viruses are classified as sub cellular particles
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