biology chapter 18 sections 1-3 (Lawrence)

What are the three types of viruses?

enveloped, helical, and polyhedral

What is the protein shell around each viral particle called?


What must viruses do before they can reproduce?

infect a host's cell

What does a enveloped virus look like?

round with spikes

What does a helical virus look like?

long, narrow, and a coil shape-also has an envelope

What does a polyhedral virus look like?

many sided with triangles

A virus cannot infect a host cell unless...

its surface proteins fit receptor molecules on the host cell's surface

How do the structures of bacteriophages help them infect the host cell?

they have spikes to help them attach to the host cells

Lytic infection: takes control of _____

the host cell's DNA

Lytic infection: Produces new_____


Lytic infection: Does what to make new viruses release?

dissolves cell membrane

Lysogenic infection: When viral DNA combines with the host cell what happens?

new genes are produced called prophage

Lysogenic infection: What happens after prophages are produced?

the host cell divides and passes on the new genes

What does a Lysogenic infection and a Lytic infection have in common?

they both infect the host cell and infect cells using genetic material

Vocab: Bacteriophage

virus that infects bacteria

Vocab: prophage

viral DNA plus host cell DNA

Vocab: capsid

a protein shell of a virus

Vocab: lysogenic infection

infection where virus combines its DNA with host cell's DNA

Vocab: lytic infection

infection where host cell bursts, releasing viral offspring

What is bacteria?

one celled microrganisms that can cause infection

What are viruses?

single strand of DNA or RNA surrounded by a protein coat that can cause infection

What does bacteria and viruses have in common?

they both are considered pathogens and can cause disease

Why is it hard to tell if viruses are alive?

they cannot reproduce or make a protein on their own and need living things to help them

Was the virus classified by Linneaus?


What is a viroid?

a single strand of RNA that causes diseases in plants (no protein coat)

What is a prion?

proteins that make other proteins fold incorrectly (no genes)

What disease is cause by prions?

mad cow disease

_____ include infectious bacteria


_____ is made of only RNA


_____ is made of only proteins


_____ is any living thing or particle that can cause infectious disease


_____ do not have any genes


What is an epidemic?

a rapid outbreak of an infection

What is a vaccine?

a substance that stimulates the body's own immune response against invasion by microbes

What is a retrovirus?

a virus that contains RNA and uses an enzyme called reverse transcriptase to make a DNA copy

What is the body's first defense against viruses?


What is a common way to get sick?

through mucous membranes in the nose or mouth

How do viruses trick cells into letting them in?

by using their surface proteins as "keys" to the cells receptors

Why do new flu vaccines have to be made every year?

new mutations of the flu every year that are different from last years

_____ virus attacks white blood cells from the bodies immune system


a vaccine is a _____ version of the same pathogen that causes the disease that the vaccine is intended to prevent


vaccines put the body in a ____ response