ch. 20 -- viruses test (biology) Flashcards
What is a virus?
A virus is a nonliving particle made of proteins, nucleic acids, DNA or RNA, and sometimes lipids
Describe the basic structure of a virus.
there is a capsid surrounding the virus, an additional membrane that surrounds that capsid, RNA or DNA. Comes in all different shapes and sizes. Proteins on the outside (act as identifiers)
What surrounds all viruses and what is it made of?
A capsid surrounds all viruses. It is made of proteins
What does a virus have inside that has the instructions for making copies of the virus?
DNA or RNA (never both)
True/False? Viruses only come in THREE shapes, THREE sizes, and TWO structures?
false (many different shapes, sizes, and structures)
what is on the outside of a virus that acts as identifiers?
proteins
What do specific proteins on the outside of a virus do? Why do they do this?
They act as identifiers. They do this to recognize and bind to specific receptors on a cell.
Most viruses infect a ____________ cell.
specific type of
What are viruses that only infect bacteria called?
bacteriophages
Why are viruses not living?
they cannot reproduce on their own
what are the two types of viral infections?
lytic and lysogenic infections
what does it mean to lyse the cell?
the cell bursts open
what of the two viruses automatically begins chopping up the host cell’s DNA?
lytic
What viral infection never leaves your body? Why?
Lysogenic viral infection. Places the DNA or RNA into the host cell DNA
what is prophage?
Viral DNA that is incorporated into host DNA
What are the two ways a virus can cause disease?
directly destroying living cells or by affecting cellular processes in ways that upset homeostasis
be able to label the head, tail fibers, sheath, and DNA of a bacteriophage
What are 2 ways we can prevent viruses? Explain both in detail.
- Vaccinations – injection of a vaccine (a weakened or a similar, but less dangerous pathogen (virus)) to help the body produce immunity
- Personal hygiene – (2 examples needed on test) – wash your hands, it dislodges the viruses off the surface. Don’t share drink or food, not sharing food or drink prevents ingestion of the virus or come in contact with a virus
What treatments do we have for viruses? Explain what is used and what they do.
Antiviral drugs – they’re drugs that attack specific viral enzymes that the virus has and the host does not. They are used to speed recovery from the viral infections or stop activation of the viral infections in other cells (Tamiflu, HIV)
What does a virus have to have to survive? Why?
A virus has to have a living host. It hijacks the cellular processes and if the host is not living it will not divide and replicate the virus
Explain the lytic cycle:
a bacteriophage attaches to the host cell and injects its DNA
bacteria is chopped up and new capsid proteins are made
DNA is copied
the viral DNA assembles together
the cell lyses and the T4 travels out and infects other cells
explain the lysogenic cycle:
a daughter cell with a prophage
prophage integrates into the bacterial chromosome, becoming a prophage
the bacterium reproduces normally, copies the prophage and transmits it to daughter cells
