Lec 1: Introduction

Question 1

virus =

Answer 1

a very small, non-cellular parasite of cells

Question 2

virus genome is composed of either,

&…

Answer 2

DNA or RNA,

& enclosed in a protein coat

Question 3

submicroscopic =

Answer 3

too small to see under scope

Question 4

viruses are obligate

Answer 4

intracellular parasites

Question 5

largest virus aka

is bigger than

Answer 5

“Mimivirus”

is bigger than smallest bacteria

Question 6

are viruses always smaller in size than bacteria?

what about their genome size?

Answer 6

Mimivirus has larger anatomical size AND genome size than smallest bacteria (mycoplasma)

Question 7

why do we study viruses? (3)

Answer 7

• some viruses cause disease
• some viruses are useful
• virus studies have been contributed to knowledge

Question 8

Uses for viruses (6) & examples (4):

Answer 8

1. ) phage typing of bacteria (ex: salmonella species)
2. ) sources of enzymes (ex: reverse transcriptase)
3. ) pesticides (ex: baculoviruses controls some insects)
4. ) anti-bacterial agents
5. ) anti-cancer agents (ex: genetically mod.’d viruses infect & destroy cancer cells, but do not harm normal cells)
6. ) gene vectors

Question 9

Much of the basic knowledge of ___ _______, ________ ______, & ____ has been derived from studies of _______
2 examples of major discoveries =

Answer 9

cell biology, molecular biology, & cancer
viruses
ex: Alfred Hershey & Martha Chase Experiment, Introns

Question 10

Hershey-Chase Experiment proved

Answer 10

that DNA is the genetic material that comprises genes

Question 11

Hershey-Chase Experiment explanation:

Answer 11

Using bacteriophages,

1. ) sulfur labeled protein capsule, infection, centrifugation…. no sulfur in cells
2. ) phosphorous labeled DNA, infection, centrifugation… phosphorous in cells!

Question 12

Studies of Adenovirus transcription allowed for the discovery of

Answer 12

introns

Question 13

introns =

Answer 13

section of DNA that doesn’t transcribe/code for genes

Question 14

RNA splicing =

Answer 14

joining of exons in a precursor molecule

Question 15

virus particles are produced from the assembly of…

while others…

Answer 15

preformed components…

…while others grow/reproduce from division

Question 16

virions =

Answer 16

virus particles

Question 17

virions do not

Answer 17

grow or divide

Question 18

viruses lack

Answer 18

the genetic information that encodes tools necessary for the generation of metabolic energy or protein synthesis (ribosomes)

Question 19

a virus genome is composed of one of the following: (4)

Answer 19

ssDNA
dsDNA
ssRNA
dsRNA

Question 20

viruses have

Answer 20

genes

Question 21

viruses use

&…

Answer 21

host cells proteins
…genomes of large viruses duplicate some of the functions of the host cells, but the small viruses rely heavily on functions of the host cell

Question 22

viruses code

&…

Answer 22

efficiently

…there may be overlapping genes encoded within genes

Question 23

many virus proteins are

&…

Answer 23

multifunctional

…a virus protein may have several enzyme activities

Question 24

Humans = _ genes = _ proteins
Viruses = _ genes = _ proteins

Answer 24

Humans = 1 genes = 1 proteins
Viruses = 1 genes = multiple proteins

Question 25

does the human genome have some viral genes?

Answer 25

yes

Question 26

3 reasons why viruses aren’t alive:

Answer 26

1. ) Viruses don’t reproduce by division, but are assembled from preformed components
2. ) Viruses can’t make their own energy or proteins
3. ) A virus-infected cell is more like a factory than a womb

Question 27

a new virion is never formed from

Answer 27

a pre-existing virion

Question 28

Viruses need: (3)

Answer 28

1. ) building blocks such as Amino Acids and Nucleosides
2. ) protein-synthesizing machinery (Ribosomes)
3. ) energy, in the form of ATP

Question 29

2 reasons why viruses are alive:

Answer 29

1. ) viruses have genes and when they infect, these genes are replicated
2. ) viruses outside of host cell exist as virions, which are inert, and t.f. non-living… but bacterial spores are inert and not considered to be nonliving