Micro Exam 4 Virus - a genetic element that contains either RNA or DNA surrounded by a protein capsid and that replicate only inside host cells Obligate intracellular parasite - Cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses Capsid - the protein shell that surrounds the genome of a virus Nucleocapsid - nucleic acid + protein in enveloped viruses Envelope - viruses have an outer layer consisting of a phospholipid bilayer (from host cell membrane) and viral proteins – those without envelope are easier to kill Virion – inactive form of virus outside the host cell Capsomere - identical protein subunits that spontaneously self-assemble into a finished capsid icosahedron – one of 2 types of capsids (the other is helical) Genome - the sum total of the genetic information carried by an organism Bacteriophage - “bacteria eating” viruses that infect bacteria Temperate phage: Undergo adsorption and penetration, do not undergo replication or release immediately Viral DNA enters a Prophage state Inserted into bacterial chromosome → Copied during normal bacterial cell division Induction - prophage in a lysogenic cell becomes activated and progresses directly into viral replication and the lytic cycle lysogeny - a condition in which the host chromosome carries bacteriophage DNA lysogenic conversion - when a bacterium acquires a new trait from its temperate phage: Corynebacterium diphtheriae – diphtheria toxin Vibrio cholerae – cholera toxin Clostridium botulinum – botulinum toxin Monolayer - single, confluent sheet of cells that supports viral multiplication Plaques - areas where virus-infected cells have been destroyed show up as clear, well-defined patches in the cell sheet

Virus

a genetic element that contains either RNA or DNA surrounded by a protein capsid and that replicate only inside host cells

Obligate intracellular parasite

Cannot multiply unless they invade a specific host cell and instruct its genetic and metabolic machinery to make and release new viruses  

Capsid

the protein shell that surrounds the genome of a virus  

Nucleocapsid

nucleic acid + protein in enveloped viruses 

Envelope

viruses have an outer layer consisting of a phospholipid bilayer (from host cell membrane) and viral proteins – those without envelope are easier to kill  

Virion

inactive form of virus outside the host cell  

Capsomere

identical protein subunits that spontaneously self-assemble into a finished capsid 

icosahedron

one of 2 types of capsids (the other is helical)  

Genome

the sum total of the genetic information carried by an organism 

Bacteriophage

“bacteria eating” viruses that infect bacteria  

Temperate phage

Undergo adsorption and penetration, do not undergo replication or release immediately 

Viral DNA enters a _____ stage

Prophage state

what is the Prophage state

Inserted into bacterial chromosome → Copied during normal bacterial cell division 

Induction

prophage in a lysogenic cell becomes activated and progresses directly into viral replication and the lytic cycle 

lysogeny

a condition in which the host chromosome carries bacteriophage DNA 

lysogenic conversion

when a bacterium acquires a new trait from its temperate phage: 

• Corynebacterium diphtheriae – diphtheria toxin 

• Vibrio cholerae – cholera toxin  

• Clostridium botulinum – botulinum toxin 

Monolayer

single, confluent sheet of cells that supports viral multiplication 

Plaques

areas where virus-infected cells have been destroyed show up as clear, well-defined patches in the cell sheet