viruses

lysogenic/temperate phage

-happens naturally -lysed bacterium releases DNA that is transferred to a living bacterium via phage -useful for research bc the genes of the phage that can be used to insert genes into bacterial chromosomes

capsomers

Each capsid is made of identical protein subunits called

compare the "life cycles" of the lytic cycle and the lysogenic bacteriophages. Can the same phage be both?

Lytic Cycle: a phage replicative cycle that ends in host cell death Lysogenic Cycle: a phage replicative cycle that doesn't destroy host Bacteriophages are viruses that infect bacteria. Bacteriophages may have a lytic cycle or a lysogenic cycle, and a few viruses are capable of carrying out both

acellular

Not made up of or containing cells

what kind of nucleic acid do viruses have?

RNA or DNA

helical capsid

Rod-shaped capsomeres that form a continuous helix around the nucleic acid

isohedral

Some capsids are this. 20 sides of same protein patterns. Variations among capsomers, also with and without an envelope.

how can a virus cause cancer?

Some viruses do this by inserting their own DNA (or RNA) into that of the host cell. When the DNA or RNA affects the host cell's genes, it can push the cell toward becoming cancer.

host range

The limited range of host cells that each type of virus can infect and parasitize.

what are the three categories of viral shapes

The three major shapes seen are spherical, filamentous, and complex.

why is there some debate about whether or not viruses are alive?

Viruses contain unique genetic information which supports the argument that they could be alive. Fundamental to the argument that viruses are not alive is the suggestion that metabolism and self-sustaining replication are key definitions of life. Viruses are not able to replicate without the metabolic machinery of the cell.

are viruses single or double stranded? can you have both?

We often think of DNA as double-stranded and RNA as single-stranded, since that's typically the case in our own cells. However, viruses can have all possible combos of strandedness and nucleic acid type (double-stranded DNA, double-stranded RNA, single-stranded DNA, or single-stranded RNA).

envelope

a membranelike layer that covers the capsids of some viruses -taken from an animal cell -not all viruses have these

capsid

all viruses have a capsid -shell that surrounds the nucleic acid in the central core

adsoprtion

invasion of host cell by binding to specific receptors

lysogenic phage

involves the incorporation of the viral genome into the host cell genome, infecting it from within

just nucleocapsid?

naked virus

latent state

no symptoms or clinical signs evident

can you see a virion with a light microscope

no viruses are too small to be seen under a light microscope

Are viral spikes found on naked viruses?

no, they are found on enveloped viruses

what are cancer causing viruses called?

oncavirus

spikes

projections that extend from the viral envelope that may aid in attachment to the host cell

lytic phage

repro if viruses using a host cell to make more viruses then bursting the cell

prions

infectious proteins

oncovirus

-some viruses permanently alter the DNA of the host cell -can cause cancer (cells replicate larger, faster, with diff cell membranes and chromosomes)

prophage

A phage genome that has been inserted into a specific site on the bacterial chromosome.

bacteriophage

A virus that infects bacteria

complex virus

A virus with a complicated structure, such as a bacteriophage.

reverse transcriptase

An enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis.

why are some viruses enveloped? what is the envelope made from?

an envelope is a phospholipid bilayer membrane that surrounds the virus. When the viruses leave the cell, the membrane proteins are replaced with viral proteins. The viral proteins are a signaling molecule where the nucleic acid should localize for the host cell membrane (endocytosis). It pinches off a little piece of the host cell membrane and then you end up with a free infectious virus. Some of the viral proteins are glycoproteins or spikes which interact with the host cell membrane receptors of the new host cell. SO they can trick the host cell into bringing the virus inside and replicating it. An envelope is going to allow for more flexibility and variation of shape. Not only is it an extra layer of protection but it is able to flex and absorb force.

list the 6 steps of viral replication

attachment, penetration, uncoating, replication, assembly, and virion release.

plaques

clumps of a protein called beta-amyloid, found in brain tissues surrounding the neurons

transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret.

uncoating

enzymes in the vacuoles will degrade/uncoat the virus. some viruses fuse with the cell membrane facilitating penetration

phage

formally known as bacteriophages, are viruses that solely kill and selectively target bacteria.

all viruses are made of what 2 things?

he basic structure consists of a protein shell (capsid) surrounding nucleic acid (DNA or RNA). The nucleic acids can be single stranded or double stranded, but not both at the same time. On the capsid there are molecules that are very important for attaching to the host cell. Specificity is going to be very important for the host range of a virus.

synthesis

if nucleic acid is RNA it can be translated in the cytoplasm if nucleic acid is DNA it will enter the host cells nucleus and be replicated

retrovirus

some RNA strands are turned into DNA and then back into RNA (performed by host cell machinery)

release

some viruses become so numerous and lyse the cell others are released through exocytosis

nucleocapsid

the capsid together with the nucleic acid

assembly

the host cells makes all the components of the virus and assembles them usually the capsid is formed, and the nucleic acid is inserted the spikes are also inserted in to the host cell membrane so they can be added as the virus leaves

enveloped viruses are usually parasites of what type of cell?

the viral envelope comes from a host cell membrane, and most enveloped viruses are animal viruses because animal cells are the ones that only have a cell membrane.

how can bacteria acquire new genes via a virus

transduction is a process by which a virus transfers genetic material from one bacterium to another bacterium. This process depends on a specific type of virus called a bacteriophage, which is capable of infecting bacterial cells and using them as hosts to produce more viruses.

penetration

virus is engulfed into a vesicle

naked virus

virus without an envelope

cytopathic effects

virus-induced damage to the cell that alters its microscopic appearance