Biology U2 L1 Viruses

What happens after a virus infects a cell?

Inside living cells, viruses use their genetic information to make multiple copies of themselves. Some viruses replicate immediately, while others initially persist in an inactive state within the host

retrovirus

RNA virus that contains RNA as its genetic information

How does a retrovirus reproduce?

a retrovirus infects a host cell & uses an enzyme called reverse transcriptase to copy RNA into DNA. the virus's DNA is then incorporated into the host cell's genome where it is reproduced along with the host cell's DNA. At some later date, the virus's genetic material is activated & copies of its RNA are made. The RNA is covered in viral proteins that the cell is also directed to make & new viruses are formed

prophage

bacteriophage DNA that is embedded in the bacterial host's DNA. *a piece of virus DNA that becoems a part of a bacterium's genome *It may replicate the bacterium for many generations. *It can exit the bacterial chromosome & enter the Lytic cycle.

capsid

protein coat surrounding a virus

When did scientists first get a look at a virus? What method did they use?

scientist saw the first virus in the 1950s using an electron microscope

How is this different from other viruses?

the genetic material of most viruses, either DNA or RNA, gets copied in its original form. A retrovirus, however, uses reverse transcriptase to covert its RNA in DNA

lysogenic infection

type of infection in which a virus embeds its DNA into the DNA of the host cell and is replicated along with the host cell's DNA

lytic infection

type of infection in which a virus enters a cell, makes copies of itself, and causes the cell to burst

How do scientists view the structures of viruses?

Viruses can be viewed with an electron microscope

How are viruses different from cells? How are they similar?

Viruses do not have a nucleus or many of the other structures that cells have. However, they are chemically similar to other life forms

How do viruses reproduce?

Viruses infect living cells & use the host cells machinery to make copies of themselves. They then burst out of the cell & look for new host cells to attack

Explain how a virus reproduces and how other cells become infected.

A virus infects a host cell, takes over the cell's protein-making processes and begins to make copies of itself. You may recall from previous lessons that several proteins are necessary to duplicate DNA and RNA molecules. Viruses do not contain these proteins, but they need them to reproduce so they use the host cell's proteins. After many copies of the virus have been made, the viruses are released from the cell & they infect other cells

About viruses

All viruses must infect a host cell in order to reproduce. However, viruses that reproduce through lytic infection begin to make copies of themselves immediately. Viruses that reproduce through lysogenic infection remain dormant for a period of time before new viruses are made.

List two names of viruses and describe what cells they attack.

Measles and influenza (the flu). Measles attack skin cells & influenza virus attack cells in the throat respiratory system

Which virual structure enables a virus to bind to receptors on the cell? *tail fiber *tail sheath *head *capsid

capsid

bacteriophage

kind of virus that infects bacteria. The two types are lysogenic infection & lytic infection

the life cycle of a lytic virus DOES NOT involve *replication *lysogenic infection *infection *cell death

lysogenic infection

a non living particle that contains DNA or RNA & is protected by a protein coat is called a *protein *cell *virus *bacterium

virus