Biology: 19.2 Viruses

Once virus inside host cell, 2 dif processes may occur:

-some replicate themselves immediately- kill host cell -others replicate themselves- doesn't kill host cell immediately

Cell reproduction:

Asexually, sexually

Retroviruses genetic info. is copied ___. ___ -> ___

Backwards, RNA -> DNA

How do viruses reproduce?

By only infecting living cells

Cell structure:

Cell membrane, cytoplasm, nucleus, organelles

In a lytic infection, a virus enters a cell, makes ... & causes cell to ___

Copies of itself, burst

Cell gen. code:

DNA

Host cell can't tell dif between its own ___ & ___

DNA & RNA

Typical virus is composed of a core of ___ & ___ surrounded by ___ ___

DNA & RNA, protein coat

When retroviruses infect cell, they produce ___ copy of their ___

DNA, RNA

In a lysogenic infection, virus integrates its ___ into DNA of ___ ___, & viral genetic info. replicates along w/ ...

DNA, host cell, host cell's DNA

Virus gen. code:

DNA/ RNA

Virus structure:

DNA/ RNA core, capsid

After infecting living cells, can: ___, ___, ___

Evolve, regulate gene expression, reproduce

Lysogenic infection

Host cell makes copies of virus immediately

What do viruses differ in?

In size & structure

Unlike lytic viruses, lysogenic viruses don't ___ right away, remains ___ ° of time

Lyse, inactive

They enter living cells & once inside, use ___ of ___ ___ to produce more ___

Machinery, infected cell, viruses

Viruses alive or not?

Not alive

Virus reproduction:

Only within host cell

Viruses

Particles of nucleic acid, protein, & in some cases lipids

Lytic infection

Process in which virus enters cell, makes copy of itself, & causes cell to burst

Capsid includes ___. Enable ___ to ___ ___ ___

Proteins, virus, enter host cell

Capsid of proteins of virus bind to ___ on surf. of ___ & "___" cell into ___ ___

Receptors, cell, "trick", allowing inside

Viruses take advantage of host's ___, ___

Respiration, nutrition

Big or small?

Small, seen w/ electron microscope

Retroviruses

Some viruses contain RNA as their genetic info

Once inside, cell ___ & ___ viral genetic info. into ...

Transcribes & translates, viral capsid proteins

Growth/ dev

V= no C= yes

Obtain & use energy

V= no C= yes

Response to environment

V= no C= yes

Change over time

V= yes C= yes

Prophage

Viral DNA that's embedded in host's DNA

Capsid

Virus's protein coat

Bacteriophages

Viruses that infect bac.