Flashcards in Lecture 14 Deck (60):
1
What is even the smallest bacteria capable of?
independent replication, synthesis of energy and proteins, cell enclosed with DNA and RNA
2
What do viruses not have?
cell wall, cytoplasm, ribosomes/mitochondria, nucleus, independent replication
3
Does nature have RNA carrying genetic information?
NO- not found in nature
4
Will viruses contain DNA and RNA?
Not both at the same time- one or the other
5
DO RNA viruses carry genetic information?
YES
6
Can virues synthetize their own energy or proteins?
NO
7
Can viruses be seen under a microscope?
NO- too small
8
How do antibiotics affect viruses?
THey are resistant to all antibiotics
9
What did Geirer and Schraman do?
extracted the infectious nucleic acid which produced disease in the host cells confirming it as living chemicals
10
Most viruses are what shape?
spherical
11
define virons
extracellular virus particles- vary in size from 20-300nm
12
What is the biggest virus equal to?
the size of the smallest bacteria (micro plasm)
13
List shapes of viruses
spherical, complex, bullet shaped/brick shaped
14
What can viral nucleic acids be extracted with?
phenol/detergents
15
What parts make up the viral structure?
central nucleic acid, protein coat (capsid), some may have an envelop
16
What part of the virus protects the nucleic acid and is the basic structure of a virus?
capsid- facilitates absorption
17
What is the envelop of the cell made up of?
envelop is a lipid layer derived from host cell during budding
18
Are viruses heat labile?
YES
19
At what temperature are viruses inactivated within a few seconds?
56 degrees celcius
20
What inactivates viruses?
sunlight, UV light
21
What are viruses resistant to?
chemical disinfectants- lysol for example
22
How doe viruses replicate?
disassemble into patricles inside the cell, multiply separately and then assemble- one virion giving rise to hundred of virion particles
23
Process of adsorption of a virus
virus adsorbed to host cell- there are specific receptors on host cell for viruses
24
Penetration of a virus
penetrate into the cell
25
Uncoating of a virus
stripping of virus from capsid by lysozyme of the cell
26
Process of virus attacking
absorption, penetration, uncoating, biosynthesis, maturation, release
27
Process of biosynthesis of virus
synthesis of enzymes for stages of viral replication, assembly and release. Followed by synthesis of nucleic acid and capsid protein takes place separately
28
Where does synthesis of nucleic acid take place?
nucleus
29
Where does synthesis of viral proteins occur?
cytoplasm
30
Where does RNA viruses synthesize nucleic acid and proteins?
cytoplasm
31
Process of maturation of virus
nucleic acid and viral proteins assembled together and form viral particle
32
Process of release of virus
done by cell lysis (non enveloped virus) or budding (enveloped virus)
33
Replication times for human virus
15-30 hours
34
Replication time for baceria
15-30 minutes
35
define Lysogenic cycle
alternate pathway of viruses in which viral genome (DNA) becomes integrated with host cell genome and multiply along with it
36
Name for the integrated viral DNA
prophage
37
What is the lysogenic cycle well studied for?
lambda bacteriophage
38
transduction
transferring of a gene
39
why would a virus infected cell undergo death of cell?
inhibition of protein, nucleic acid synthesis
40
list morphological changes of a viral infected cell
inclusion bodies, fusion of virus infected cells to form multinucleated giant cells, cytopathic effect, malignant transformation and cellular proliferation, no morphological/functional change
41
define cytopathic effect
darkening and rounding which may culminate in lysis/giant cell formation
42
forms of transmission of virus
through respiratory tract, skin, conjunctiva, genital tract
43
How are viruses spread person to person?
through respiratory tract, saliva, blood or semen, fecal contamination of water and food
44
How are viruses spread from mother to baby?
placenta or breast milk- vertical transmission
45
How are viruses spread animal to human?
by vectors (ex. yellow fever)
46
In what disease is virus spread systemically through body?
polio
47
What does cell killing result in?
loss of function and symptoms
48
non specific host defense against viral infections
interferon, NK cells, fever
49
Specific defense against viral infections
humoral Antibiotics & CMI
50
What is the main defense mechanism in viral infections?
specific immunity
51
define Natural Killer Cells
a type of T lymphocyte that recognize virus infected cells and kill them
52
Define Interferons
glycoproteins produced by leukocytes (neutrophils) during viral infection
53
What eliminates non specific visions?
fever- especially help enveloped virions
54
4 types of specific antibodies
IgA, IgM, IgG, and IgE
55
What does IgA protect?
respiratory and gastro infections
56
What does IgM and IgG protect?
against viruses entering blood
57
What do antibodies do?
neutralize viruses, facilitate phagocytosis, interferes with adherence and penetration, cause lysis of virus infected cells
58
What cell causes cell mediated immunity?
cytotoxic T cells- killing viral infected cells
59
What antibodies for passive immunity?
IgG and IgM
60