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;
14 Cards in this Set
- Front
- Back
|
What is a virus particle (Virion)?
|
infectious form of virus that exists outside host and facilitate transmission from one host to another
|
|
|
What is a virion composed of?
|
Nucleic acid genome surrounded by protein coat and in some cases a lipid membrane layer
|
|
|
What are characteristics of a viral genome?
|
DNA/RNA
double or single stranded Mostly linear very specific Size range=0.02 to 0.3 um |
|
|
What is a capsid?
|
protein shell that surrounds the genome of a virus particle: Composed of capsomeres arranged in repetition around nucleic acid genome
|
|
|
What is a capsomere
|
Protein subunit of rapid
|
|
|
Nucleocapsids are highly symmetric. What are types of symmetry?
|
Helical symmetry: rod shaped virus (ex. tobacco mosaic virus)
Icosahedral symmetry: spherical viruses |
|
|
What enzymes do virions contain?
|
1) Lysozyme: lyse bacterial cell wall
2) Nucleic acid polymerases: For replication of viral genome, not dsDNA |
|
|
What is a titer?
|
Number of infections units per volume of fluid
|
|
|
What is efficiency of plating?
|
Number of plaque forming units always lower than microscope counts:
-inactive virions -mutant genomes -conditions not appropriate in lab for infectivity |
|
|
Phases of viral replication?
|
1) Attachment (adsorption)
2) Entry 3) Synthesis 4) Assembly 5) Release |
|
|
What mechanisms do bacteria contain to diminish viral infection?
|
1) CRISPR: similar to RNA interference
2)Restriction-modification system: effective against dsDNA virus, restriction enzymes cleave DNA, Modifies host own DNA to prevent cleavage of own DNA |
|
|
Characteristics of early viral proteins?
|
-synthesized soon after infection
-necessary for replication of virus nucleic acid -typically act catalytically -made in small amounts |
|
|
Characteristics of late viral proteins?
|
-synthsized later
-include proteins of virus coat -typically structural components -made in larger amounts |
|
|
!Special modification in Phage T4 DNA?
|
contains modified base: 5-hydrozymethylcytosine, DNA is resistant to most restriction enzymes!
|
