Micro Lecture Ch 5

Virus

A genetic element that can multiply only in a living (host) cell and is considered an obligate intracellular parasite.

Virion

The extracellular form of a virus that exists outside the host and facilitates transmission between host cells.

Capsid

The protein shell that surrounds the genome of a virus.

Naked viruses

Viruses that do not have any additional layers beyond the capsid.

Enveloped viruses

Viruses that have an outer layer consisting of a phospholipid bilayer from the host cell membrane and viral proteins.

Nucleocapsid

The combination of nucleic acid and protein in enveloped viruses.

Virulent (lytic) infection

An infection where the virus replicates and destroys the host cell.

Lysogenic infection

An infection where the host cell is genetically altered because the viral genome becomes part of the host genome.

Viral diversity

The classification of viruses based on the type of hosts they infect and their genetic material.

Bacteriophage

A type of virus that specifically infects bacteria.

Plaque assay

A method used to detect and count viruses by measuring clear zones of cell lysis on lawns of host cells.

Titer

The number of infectious virions per volume of fluid.

Eclipse phase

The period in viral replication where the genome is replicated and proteins are translated, but no virions are yet present.

Maturation phase

The stage in viral replication characterized by the packaging of nucleic acids in capsids.

Lytic cycle

The viral reproduction cycle that results in the destruction of the host cell.

Temperate bacteriophage

Viruses that establish a long-term relationship with the host and can enter a lysogenic state.

Lysogeny

A state in which the viral genome is replicated with the host's chromosome and passed to daughter cells.

Prophage

Viral DNA that has integrated into the bacterial chromosome during lysogeny.

Viroplasm

Membrane-bound viral factories that form in some eukaryotic cells to increase the assembly rate of virions.

Reverse transcriptase

An enzyme used by retroviruses to convert RNA to DNA.

Neuraminidases

Enzymes that destroy glycoproteins and glycolipids, allowing for the release of viruses from cells.

Lysozyme

Enzyme that makes holes in the cell wall to allow nucleic acid entry and lyses bacterial cells to release new virions.

Eclipse period

The phase in the viral life cycle when no virions are detected due to cellular machinery being redirected to produce viral components.

Host specificity

The property that refers to the ability of a virus to infect certain types of hosts.

Penetration phase

The stage in the viral replication cycle where the virion enters the host cell.

Genomic integration

The process by which viral DNA becomes part of the host cell's genome.

Budding

The process by which enveloped viruses exit the host cell, acquiring a portion of the cell's membrane.

Viral proteins

Proteins encoded by the viral genome that are essential for viral replication and assembly.

Lytic pathway

The process by which a virus destroys its host cell to release new virions.

Infection cycle

The series of steps that a virus goes through to infect a host cell and replicate.

Proteins for attachment

Viral proteins found on the surface of virions that are important for attaching to host cells.

Single-stranded RNA (ssRNA)

A type of viral RNA that has only one strand of nucleic acid.

Double-stranded DNA (dsDNA)

A type of viral DNA composed of two complementary strands.

Incubation period

The time from infection to the appearance of symptoms or detectable viral particles.

Infectivity

The ability of a virus to establish an infection in a host.

Viral envelope

A lipid bilayer that surrounds some viruses and helps them enter host cells.

Cell lysis

The breaking down of the cell membrane, leading to cell death and release of viral particles.

Viral transformation

The process where a virus causes normal cells to become cancerous.

Antiviral CRISPR

A bacterial immune mechanism that targets viral DNA for degradation.

Restriction endonucleases

Enzymes that cut foreign DNA at specific sites to defend against viral infections.

Influenza virus

A virus that causes respiratory illness and is characterized by its RNA genome.