Lecture 14

Question 1

What is even the smallest bacteria capable of?

Answer 1

independent replication, synthesis of energy and proteins, cell enclosed with DNA and RNA

Question 2

What do viruses not have?

Answer 2

cell wall, cytoplasm, ribosomes/mitochondria, nucleus, independent replication

Question 3

Does nature have RNA carrying genetic information?

Answer 3

NO- not found in nature

Question 4

Will viruses contain DNA and RNA?

Answer 4

Not both at the same time- one or the other

Question 5

DO RNA viruses carry genetic information?

Answer 5

YES

Question 6

Can virues synthetize their own energy or proteins?

Answer 6

NO

Question 7

Can viruses be seen under a microscope?

Answer 7

NO- too small

Question 8

How do antibiotics affect viruses?

Answer 8

THey are resistant to all antibiotics

Question 9

What did Geirer and Schraman do?

Answer 9

extracted the infectious nucleic acid which produced disease in the host cells confirming it as living chemicals

Question 10

Most viruses are what shape?

Answer 10

spherical

Question 11

define virons

Answer 11

extracellular virus particles- vary in size from 20-300nm

Question 12

What is the biggest virus equal to?

Answer 12

the size of the smallest bacteria (micro plasm)

Question 13

List shapes of viruses

Answer 13

spherical, complex, bullet shaped/brick shaped

Question 14

What can viral nucleic acids be extracted with?

Answer 14

phenol/detergents

Question 15

What parts make up the viral structure?

Answer 15

central nucleic acid, protein coat (capsid), some may have an envelop

Question 16

What part of the virus protects the nucleic acid and is the basic structure of a virus?

Answer 16

capsid- facilitates absorption

Question 17

What is the envelop of the cell made up of?

Answer 17

envelop is a lipid layer derived from host cell during budding

Question 18

Are viruses heat labile?

Answer 18

YES

Question 19

At what temperature are viruses inactivated within a few seconds?

Answer 19

56 degrees celcius

Question 20

What inactivates viruses?

Answer 20

sunlight, UV light

Question 21

What are viruses resistant to?

Answer 21

chemical disinfectants- lysol for example

Question 22

How doe viruses replicate?

Answer 22

disassemble into patricles inside the cell, multiply separately and then assemble- one virion giving rise to hundred of virion particles

Question 23

Process of adsorption of a virus

Answer 23

virus adsorbed to host cell- there are specific receptors on host cell for viruses

Question 24

Penetration of a virus

Answer 24

penetrate into the cell

Question 25

Uncoating of a virus

Answer 25

stripping of virus from capsid by lysozyme of the cell

Question 26

Process of virus attacking

Answer 26

absorption, penetration, uncoating, biosynthesis, maturation, release

Question 27

Process of biosynthesis of virus

Answer 27

synthesis of enzymes for stages of viral replication, assembly and release. Followed by synthesis of nucleic acid and capsid protein takes place separately

Question 28

Where does synthesis of nucleic acid take place?

Answer 28

nucleus

Question 29

Where does synthesis of viral proteins occur?

Answer 29

cytoplasm

Question 30

Where does RNA viruses synthesize nucleic acid and proteins?

Answer 30

cytoplasm

Question 31

Process of maturation of virus

Answer 31

nucleic acid and viral proteins assembled together and form viral particle

Question 32

Process of release of virus

Answer 32

done by cell lysis (non enveloped virus) or budding (enveloped virus)

Question 33

Replication times for human virus

Answer 33

15-30 hours

Question 34

Replication time for baceria

Answer 34

15-30 minutes

Question 35

define Lysogenic cycle

Answer 35

alternate pathway of viruses in which viral genome (DNA) becomes integrated with host cell genome and multiply along with it

Question 36

Name for the integrated viral DNA

Answer 36

prophage

Question 37

What is the lysogenic cycle well studied for?

Answer 37

lambda bacteriophage

Question 38

transduction

Answer 38

transferring of a gene

Question 39

why would a virus infected cell undergo death of cell?

Answer 39

inhibition of protein, nucleic acid synthesis

Question 40

list morphological changes of a viral infected cell

Answer 40

inclusion bodies, fusion of virus infected cells to form multinucleated giant cells, cytopathic effect, malignant transformation and cellular proliferation, no morphological/functional change

Question 41

define cytopathic effect

Answer 41

darkening and rounding which may culminate in lysis/giant cell formation

Question 42

forms of transmission of virus

Answer 42

through respiratory tract, skin, conjunctiva, genital tract

Question 43

How are viruses spread person to person?

Answer 43

through respiratory tract, saliva, blood or semen, fecal contamination of water and food

Question 44

How are viruses spread from mother to baby?

Answer 44

placenta or breast milk- vertical transmission

Question 45

How are viruses spread animal to human?

Answer 45

by vectors (ex. yellow fever)

Question 46

In what disease is virus spread systemically through body?

Answer 46

polio

Question 47

What does cell killing result in?

Answer 47

loss of function and symptoms

Question 48

non specific host defense against viral infections

Answer 48

interferon, NK cells, fever

Question 49

Specific defense against viral infections

Answer 49

humoral Antibiotics & CMI

Question 50

What is the main defense mechanism in viral infections?

Answer 50

specific immunity

Question 51

define Natural Killer Cells

Answer 51

a type of T lymphocyte that recognize virus infected cells and kill them

Question 52

Define Interferons

Answer 52

glycoproteins produced by leukocytes (neutrophils) during viral infection

Question 53

What eliminates non specific visions?

Answer 53

fever- especially help enveloped virions

Question 54

4 types of specific antibodies

Answer 54

IgA, IgM, IgG, and IgE

Question 55

What does IgA protect?

Answer 55

respiratory and gastro infections

Question 56

What does IgM and IgG protect?

Answer 56

against viruses entering blood

Question 57

What do antibodies do?

Answer 57

neutralize viruses, facilitate phagocytosis, interferes with adherence and penetration, cause lysis of virus infected cells

Question 58

What cell causes cell mediated immunity?

Answer 58

cytotoxic T cells- killing viral infected cells

Question 59

What antibodies for passive immunity?

Answer 59

IgG and IgM

Question 60

What are antibodies IgG and IgM used for?

Answer 60

rabies, Hep B, Varicella zoster