ch. 5 & 6 short answers

Question 1

explain the 5 step life cycle of animal viruses

Answer 1

absorption
penetration
synthesis
assembly
release

Question 2

absorption

Answer 2

virus enters a susceptible host cell and absorbs to receptor sites on cell membrane

Question 3

penetration/uncoating

Answer 3

the entire virus is engulfed by the cell and enclosed in a vacuole/ vesicle

Question 4

synthesis

Answer 4

the viral nucleic acid begins to synthesize the building blocks for new viruses

Question 5

assembly

Answer 5

mature virus particles are constructed from the growing pool of parts. the capsid is laid down as an empty shell that will be receptacle for the nucleic acid strand

Question 6

release

Answer 6

assembled viruses leave their host. non-enveloped viruses that reach maturation in the cell nucleus are released when the cell lyses/ruptures. the nucleocapsid binds to the membrane

Question 7

lytic bacteriophage infections

Answer 7

destroys the host cell

Question 8

lysogenic conversion

Answer 8

when a bacterium acquires a new trait from its temperate phage

Question 9

what are 3 ways in which viruses are cultivated

Answer 9

using live animal inoculation
using bird embryos
using cell (tissue) culture techniques

Question 10

3 purposes of cultivating viruses

Answer 10

isolate and identify viruses in clinical specimens
prepare viruses for vaccines
do detail research on viral structure, multiplication cycles, genetics, and effects on host cells are cultivated

Question 11

explain why antiviral drugs are difficult to develop and why its advantages to taken in the first 48 hrs of symptoms

Answer 11

viruses borrow host proteins and functions to propagate themselves, so it is difficult to find drugs that will help without damage caused to the cell

Question 12

7 properties of viruses

Answer 12

1. are obligate intracellular parasites of bacteria, protozoa, fungi, algae, plants and animals
2. are ubiquitous in nature and have had major impact on development of biological life
3. are NOT cells, structures are very compact and economical
4. do not dependently fulfill the characteristics of life
5. basic structure consists of protein shell surrounding nucleic acid core
6. nucleic acid can be RNA or DNA but NOT both
7. nucleic acid can be double stranded DNA/RNA or single stranded RNA/DNA
8. molecules on virus surface give them high specificity for attachment to host cell
9. multiple by taking control of host cell’s genetic material and regulating the synthesis and assembly of new viruses
   10 . lack enzymes for most metabolic processes
10. lack machinery for synthesizing proteins

Question 13

are viruses dead or alive? explain fully.

Answer 13

there are two viewpoints about this question: one says that since they can’t reproduce independently from the host cell, then they are not living and they should be call infectious molecules.
the other viewpoint is that even thought they don’t have most life processes the viruses can direct them and they are more inert and lifeless molecules

Question 14

3 DNA viruses

Answer 14

2 stranded:
variola virus: small pox
herpes simplex 2: genital herpes
single stranded:
parvovirus: erythema infection

Question 15

4 RNA viruses

Answer 15

single stranded
(+) poliovirus: poliomyelitis
(-) influenza virus: influenza
HIV: AIDS
double stranded:
rotavirus: gastroenteritis

Question 16

prions

Answer 16

distinct protein fibrils in the brain tissues and the agents

Question 17

prions diseases

Answer 17

creutzfeldt- jakob disease: infiltrate the CNS of humans and causes gradual degeneration and death
bovine spongiform encephalopathy: contaminated beef
shy drager syndrome/ multiple system atrophy: resembles Parkinson’s disease, accumulation of alpha-synuclein in the brain

Question 18

autotrophs

Answer 18

get their energy from CO2- get energy from sunlight and chemical reactions

Question 19

photoautotrophs

Answer 19

they capture energy and transform it into chemical energy that can be used in celll metabolism

Question 20

chemoautotrophs

Answer 20

organic compounds for energy and inorganic compounds as a carbon source

Question 21

lithoautotrophs

Answer 21

rely totally on inorganic minerals: derive energy in diverse ways like removing electrons from inorganic substrates like hydrogen gas, sulfide, sulfur, or ion and then combine then w/ CO2 and hydrogen

Question 22

chemoheterotrophs

Answer 22

derive their carbon & energy from organic compounds; they process by cell respiration/ fermentation releasing energy in the form of ATP

Question 23

saprobes

Answer 23

free living that feed primarily on organic detritus from dead organism

Question 24

parasites

Answer 24

derive nutrients from the cells of a living host

Question 25

isotonic solution

Answer 25

w/ cell wall: water concentration is equal all around, diffusion rates are equal
w/o cell wall: diffusion rates are equal in both directions

Question 26

hypotonic solution

Answer 26

w/ cell wall: diffusion of water is in the cell, swells the protoplast