Chapter 13 - Characterizing + Classifying Virus, Viroids, + Prions

Question 1

Virus

Answer 1

• minuscule
• acellular infectious agents having either DNA or RNA
• causes many infections of humans, animals, plants, + bacteria
• causes most diseased that plague the industrial world

Question 2

Virion

Answer 2

• extracellular state of virus
• capsid surrounding nucleic acid
• some w phospholipid envelope
• outermost layer provides protection and recognition sites for host cells

Question 3

Capsid

Answer 3

protein coat surrounding nucleic acid

Question 4

nucleocapsid

Answer 4

nucleic acid + capsid

Question 5

intracellular state of virus

Answer 5

• capsid is removed

- virus exists as nucleic acid

Question 6

nucleic acid and capsid are called…

Answer 6

nucleocapsid

Question 7

outermost layer of virion provides _____ + ____ for host cells

Answer 7

outermost layer provides PROTECTION + RECOGNITION SITES for host cells

Question 8

primary way to categorize + classify virus is based on…

Answer 8

the genetic material of virus

-may be DNA or RNA (never both)

Question 9

DNA or RNA of virus

Answer 9

• never both
• dsDNA, ssDNA, dsRNA, ssRNA
• much smaller than genomes of cells

Question 10

“ds” or “ss” DNA/RNA

Answer 10

double stranded or single stranded

Question 11

subunits of capsids

Answer 11

capsomere

Question 12

Viral Replication

Answer 12

lysogeny (virus takes over host cell + replication) or lysotic (phage, lysis)

Question 13

Synthesis of Animal Virus

Answer 13

• DNA virus replicates in nucleus
• RNA virus replicates in cytoplasm
• enveloped causes persistent infections
• enveloped are released by budding out of the host cell
• naked virus are released by exocytosis/lysis

Question 14

environmental factors that can activate oncogenes

Answer 14

virus, UV light, radiation, carcinogens

Question 15

Viroids

Answer 15

-NOT a virus or a virion
-extremely small, circular pieces of RNA that are infectious and pathogenic in plants
discovered in 1971
-similar to RNA virus but lack capsid + membrane
-may appear liner due to H bonding

Question 16

Prions

Answer 16

• proteinaceous infectious agents

- NOT cellular, an organism, or a microbe

Question 17

Cellular PrP protein

Answer 17

• made by mammals

- normal structure w alpha-helices called cellular PrP

Question 18

Prion PrP

Answer 18

• disease-causing form w Beta-pleated sheets called PRION PRP
• Prion PrP changes the shape of cellular PrP so it becomes prion PrP

Question 19

PrP mutations

Answer 19

• results in formation of PRION PrP

- normally, nearby proteins + polysaccharides force PrP into cellular shape

Question 20

PrP diseases

Answer 20

• fatal neurological degeneration, fibril deposits in the brain, and loss of brain matter
• spongiform encephalopathies

Question 21

spongiform encephalopathies

Answer 21

• neurological PrP disease

- large vacuoles form in brain (spongy appearance)

Question 22

PrP destruction

Answer 22

-incineration or autoclaving in 1M NaOH soln + prionzyme

Question 23

Oncogene

Answer 23

a gene which in certain circumstances can transform a cell into a tumor cell

Normal state (no cancer): gene has PROTOONCOGENE (makes oncogene) + REPRESSOR GENE (represses oncogene)

1st Viral Hit (no cancer): virus inserts PROMOTER to protooncogene but repressor gene is still active

2nd Viral Hit (cancer): virus INSERTS into repressor gene (causes segments, no repressor is produced, oncogene causes cell division)

Question 24

endotoxin

Answer 24

• gram neg

- die

Question 25

exotoxin

Answer 25

- gram pos - secrete lipid A - exocytosis