Section 4

Question 1

Why are viruses not alive?

Answer 1

do not metabolize
do not respond to stimuli
do not grow
no homeostasis
cannot reproduce alone, must have a host cell

Question 2

What characteristics do viruses have that are mimick being alive?

Answer 2

complex structures
genetic information
ability to evolve

Question 3

What is a virus’ basic structural unit?

Answer 3

a virion (a single viral particle)
virions are tiny (10 nm, or 1/1000 of a cell)
bacteriums are 10 times smaller than a cell, and virions are 10 times smaller than bacteriums

Question 4

Why are viruses NOT cells?

Answer 4

no nucleus
no organelles
no cytoplasm

Question 5

What is in the core of a virus?

Answer 5

DNA or RNA (they can switch back and forth between the two)

Question 6

What are viruses coated in?

Answer 6

a protein coat (capsid) composed of capsomeres

may also have an envelope (which is a stolen piece of membrane

Question 7

What are the steps to viral reproduction within a cell?

Answer 7

1. Attachment: virus binds to the cell’s surface receptor
2. Penetration: viral nucleic acid is released inside the host cell
3. Synthesis: the host cell manufactures viral nucleic acids and proteins
4. Assembly: new viruses are assembled from newly synthesized coat proteins, enzymes, and nucleic acids
5. Release: new viruses leave the host cell (either by popping the cell from being too full, or by punching a hole in the membrane, taking membrane pieces with it)

Question 8

How does a bacterial virus enter into a host cell?

Answer 8

it attaches to the host cell and bacteriophages inject nucleic acids into the cell