Miller and Levine Biology Ch 19
section 2 on viruses :)
Terms in this set (25)
Particles of nucleic acid, protein, and in some cases, lipids. Can only reproduce by infecting living cells.
What is a typical virus composed of?
A typical virus is composed of a core of DNA or RNA surrounded by a protein coat.
What do all viruses have in common?
They enter living cells, and once inside, use the machinery of the infected cell to produce more viruses.
About how many genes can a virus have?
Simple ones can have a few, while complex ones may have more than one hundred genes.
A virus's protein coat.
What does a capsid include?
It includes protein that enable a virus to enter a host cell.
How does a virus get into a host cell?
The capsid proteins of a typical virus bind to receptors on the surface of a cell and "trick" the cell into allowing it inside.
Viruses that contain bacteria.
A virus enters a cell, makes of itself, and causes the cell to burst.
The host cell can't tell the difference between what during a lytic infection?
Its own DNA and the DNA of the virus.
What happens when a host cell bursts?
It releases hundreds of virus particles.
The host cell makes copies of the virus indefinitely.
What happens in a lysogenic infection?
A virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell's DNA.
Viral DNA embedded into the host's DNA.
Viruses that contain RNA as their genetic information.
What are some diseases caused by retroviruses?
AIDS is a retrovirus, and some types of cancers in animals (including humans).
Where do retroviruses get their name?
Their genetic information is copied backward-- that is, from RNA to DNA. (The prefix "retro" means backward)
Why do viruses infect a living cell?
To grown and reproduce. They also take advantage of the host's respiration, nutrition, and all other functions that occur in living things.
What can a virus also be CONSIDERED as?
Are viruses alive?
If we require that living things be made up of cells and be able to live independently, then viruses are not alive. Yet, viruses have many characteristics of living things. After infecting living cells, viruses can REPRODUCE, REGULATE GENE EXPRESSION, and even EVOLVE. Viruses are at the BORDERLINE of living and non-living things.
Which is smaller; a living cell or a virus?
Viruses are smaller and simpler than the simplest cells!
How long can a virus evolve? Along with the cells they infect?
Billions of years.
What are the parts of a virus?
Nucleic acid, DNA or RNA(surrounded by protein coat/capsid) and in some cases lipids.
What are the two viral infections?
Lytic and Lysogenic infections.
What is the difference between a bacteriophage and a prophage?
A bacteriophage infects bacteria. A prophage is the viral DNA embedded in the host's DNA.