Chapter 24: Virus

Some viruses arer thought to induce ____________, a disease characterized by uncontrolled cell division

Cancer

The protein coat of a virus is called a

Capsid

All viruses reproduceby taking over the reproductive machinery of a

Cell

Which of the following human activities is most closely associated with the emergence of viruses not previously seen in humans

Clearing of forests for housing

All viruses do not have

Cytoplasm, mitochondria and ribosomes

Which of the following is not linked to cancer

Ebola Virus

In which cell cycles do viral DNA become integrated into the host cells DNA

Lysogenic

Viruses that infect a host cell and have their nucleic acid replicated but do not harm the host cell are in a __________ cycle

Lysogenic

In the _______ cycle viruses destroy the host cell

Lytic

which of the following has been the most successful at fighting viral diseases

Vaccination and Vector control

Explain why viruses are not considered to be living organisms

Viruses are not living because threy are not cellualar, cannot reproduce outside the host cell and cant make their own proteins

A typical virus consists of

a protein coat and a nucleic acid core

Which of the following contains only RNA

a viroid

Most scientists believe that viruses first appeared on the earth ________ living cells appeared

after

Antibiotics are ineffective against viral infection because

antibiotics interfere with cellular processes that viruses do not perform

Unlike viruses, prions

are composed only of protein

Bacteriophages

are viruses that infect bacteria and a have a polyhedral head and a helical tail

Biologists now know that viruses

contain RNA or DNA in a protein or lipid protein coat

Scientists first began to study viruses becasue they

could not be seen but they were causing disease

Most scientists think that early viruses originated from

existing cell plants

HIV causes AIDS by

gradually destroying a persons immune system

Which of the following is not a vector of viral diseases

prions

The capsid of virus is the

protective outer coat

Viruses

reproduce only in living cells

A virus that transcribes DNA from an RNA template is called

retrovirus

Viruses that use reverse transcriptase to cause their host cells to transcirbe DNA from an RNA template are called

retroviruses

Viruses can vary in size and

shape

Animal viruses often infect only specific host cells because

the host cell must have specific receptors for proteins on the virus surface

Why are viruses nontheless included in the study of biology

they are included because they are acvctive inside living cells

Viruses are considered nonliving because

1) They cannot reproduce by themselves, 2) they are not made up of cells 3) They cannot carry out metabolism by themselves

Tobacco masaic virus

1) are able to be crystallized 2) cause disease in tobacco plants and 3) and are smaller than bacterium

Viruses are classified according to

1) whether they contain RNA or DNA 2) the shape of their genome 3) whether they have a membrane envelope

which of the following are viral diseases of humans

Hepatitis, SARS, and shingles

An enzyme called _____________ _______________ manufactures DNA that is complementary to a virus's RNA

Reverse Transcriptase

Chickenpox and __________ are caused by the same virus

Shingles

The study of Viruses is a part of biology because

They are active inside living cells