Week 11

Question 1

virus

Answer 1

genetic element that cannot replicate independently of living host cell

Question 2

features of a virus (4)

Answer 2

1. obligatory intracellular parasite
2. lack enzymes for protein syn and atp generation
3. contain single type of nucleic acid, contain a protein coat surrounding it
4. cause the syn of specialized structures that can trans viral nucleic acid to other cells

Question 3

virus genetic material

Answer 3

dna to rna to protein

viruses have one type of nucleic acid (never both dna and rna)

can be circular, but most are linear

Question 4

capsid

Answer 4

protein coat surrounding the nucleic acid material

size is based on size of genetic material

arranged precisely and in highly repetitive pattern

Question 5

capsomeres

Answer 5

assemblies of several distinct proteins associated in specific ways

Question 6

nucleocapsid

Answer 6

complete complex of nucleic acid and protein packaged in the virion

Question 7

nucleocapsid symmetry (2)

Answer 7

1. helical symmetry
2. icosahedral symmetry (spherical)

Question 8

enveloped viruses

Answer 8

some viruses contain lipid bilayer

membrane envelope is host derived but can also have viral encoded proteins

membrane envelope makes the initial contact with host instead of nucleocapsid (naked viruses)

Question 9

complex viruses

Answer 9

virions composed of several parts, each with separate shapes and sym

icosahedral heads and helical tails

Question 10

Lysozyme

Answer 10

Makes hole in cell wall, lyses bacterial cell

Question 11

nucleic acid polymerases

Answer 11

especially important for rna viruses

Question 12

neuraminidases

Answer 12

enzyme that cleave glycosidic bonds

allows liberation of viruses from cell

Question 13

host range

Answer 13

spectrum of the host cells the virus can infect

Question 14

titer

Answer 14

number of infectious units per volume of liquid

Question 15

plaque assay

Answer 15

analogous to the bacterial colony

clear zones that develop on lawns of host cells

lawn can be bacterial or tissue culture

each plaque results from infection by a single particle

Question 16

Phases of Viral Replication (5)

Answer 16

1. attachment
2. entry
3. synthesis
4. assembly
5. release

Question 17

T-Even bacteriophages (t2, t4, t6)

Answer 17

lytic viruses, some can undergo lysogenic (temperate) cycles, phage remains inactive (latent)

Question 18

Replication of retrovirus

Answer 18

reverse transcription of one of the two rna genomes (reverse transcriptase)

integration of retroviral dna into host genome (integrase)

generation of retroviral dna

Question 19

decontamination

Answer 19

treatment of an object to make it safe to handle

Question 20

disinfection

Answer 20

directly targets pathogens, not necessarily all microorganisms

kills or severely inhibits growth

Question 21

heat sterilization

Answer 21

decimal reduction time (D), amount of time required at given temp to reduce viability

exponential relationship

heat kills faster at higher temp

most heat better than dry heat

Question 22

thermal death time

Answer 22

time to kill all cells at a given temperature; affected by population size

Question 23

inhibition

Answer 23

effectively limiting microbial growth

Question 24

sterilization

Answer 24

killing or removal of all viable organisms within a growth medium

Question 25

disinfection

Answer 25

directly targets the removal of all pathogens, not necessarily microorganisms

Question 26

antisepsis

Answer 26

disinfection of living tissue

Question 27

sanitization

Answer 27

lowering microbial counts to safe public health levels

Question 28

factors affecting antimicrobial treatments (4)

Answer 28

number of microbes exposure time specific microbial characteristics environmental influences

Question 29

viral death caused by (3)

Answer 29

alteration in membrane permeability compromising the cell wall damage to proteins and nucleic acids

Question 30

Microbial growth control: Physical (3)

Answer 30

1. heat sterilization 2. radiation sterilization 3. filter sterilization

Question 31

Microbial growth control: Chemical (2)

Answer 31

External use chemicals Other agents: antimicrobial agents antiviral agents

Question 32

Thermal death point

Answer 32

lowest temperature at which all microorganisms in a particular liquid will be killed in 10 minutes

Question 33

Decimal reduction time

Answer 33

amount of time required to reduce viability tenfold at given temperature

Question 34

Autoclave

Answer 34

Sealed heating device, steam under pressure 121C Kills endospores

Question 35

Pasteurization

Answer 35

Used heat to significantly reduce the microbial load in heat sensitive liquids not all organisms killed all known pathogenic bacteria killed

Question 36

UV radiation

Answer 36

decontamination of exposed surfaces, causes mods or breaks in DNA

Question 37

Ionizing radiation

Answer 37

electromagnetic radiation that produces reactive molecules/ions with which radiation particles collide

Question 38

-cidal

Answer 38

kills microorganisms

Question 39

-static

Answer 39

inhibits growth

Question 40

Minimum inhibitory concentration

Answer 40

smallest amount of an agent needed to inhibit the growth of a microorganism

Question 41

Zone of growth inhibition

Answer 41

area of no growth around disk

Question 42

Selective toxicity, academic and definition

Answer 42

Paul Ehrlich 1900s The ability to inhibit or kill a pathogen without affecting the host

Question 43

Penicillins

Answer 43

inhibit cell wall synthesis no crosslinking peptidoglycans b-lactam ring includes carbpenems and monobactams

Question 44

cephalosporins

Answer 44

inhibit cell wall structure resistant to penicillinases effective against many gram negatives

Question 45

Agents that target protein synthesis

Answer 45

1. chloramphenicol and aminoglycosides 2. macrolides 3. tetracycline

Question 46

What targets DNA function?

Answer 46

1. quinolones and fluoroquinolones interfere with bacterial dna gyrase, prevents supercoiling

Question 47

Agents that target metabolic function

Answer 47

Sulfonamides inhibit synthesis of a variety of essential metabolites generally bacteriostatic

Question 48

epidemic

Answer 48

new cases of a certain disease restricted to one location

Question 49

pandemic

Answer 49

epidemic of a certain disease, that has spread across human populations across a large region/continent

Question 50

Vaccines

Answer 50

Illicit a lasting immune response in the absence of a pathogen, can consist of following : killed pathogen attenuated microbes inactivated bacterial toxins

Question 51

Whole cell vaccines

Answer 51

Consist of bacteria or viruses that are either inactivated (killed) or attenuated (live but not virulent)

Question 52

Acellular or subunit vaccines

Answer 52

use of specific purified macromolecules derived from pathogenic microbes helps avoid some risk associated with whole cell vaccines Ex: capsular polysaccharides recombinant surface antigens inactivated exotoxins (toxoids)

Question 53

Adjuvants

Answer 53

mixed with antigens in vaccines to enhance the rate and degree of immunization can be any nontoxic material that prologues antigen interaction w/ immune cells and stimulates the immune response to antigen