ddt 17

Question 1

— is a tiny infectious particle consist of a nucleic core surrounded by protein coat called —

Answer 1

• virus
• capsid

Question 2

viruses require —- to reproduce ( as: chick embryos in labs )

Answer 2

living organism/ host

Question 3

the properties of virus

Answer 3

• not cellular
  -dont respire
• no metabolism of their own
• don’t break down carbon compounds
• don’t die

Question 4

the three morphological classification

Answer 4

1- helical ( as tobacco mosaic virus )
2- icosahedral: geometric icosahedron of 20 equilateral triangular faces( as adenovirus )
3- combined or complex structures ( as bacteriophage )

Question 5

the core consist of — surrounded by protein — of varying —-

Answer 5

• rna or dna
• capsid
• geometric configuration

Question 6

some viruses have —- envelop which in addition derived from the —-

Answer 6

• lipoprotein
• membrane of the hosts cell

Question 7

propagation: life cycle
1- the virus gains entry by — and is carried to the cytoplasm in a — via the cell membrane
2- leaving its protein capsule — on the cells surface
3- viral — will be released over the genetic machinery of the host cell
4- viral – becomes incorporated into the dna of the host and assuming command of —
5- the host sytheise the —- rather than its own so new viruses will be —- and — completing the life cycle

Answer 7

-endocytosis, vacuole
- redundant
- nucleic acid
- dna, genetic control
- viral proteins, generated and released

Question 8

virus is dependent on — to propagate

Answer 8

living cells

Question 9

they enter the —- and redirect the cells —-

Answer 9

host , metabolism

Question 10

they substitute the cells dna with

Answer 10

their own and produce more viruses internally

Question 11

the viral propagation stages:

Answer 11

1- attachment: involves the interaction of the viron w/ specific receptor sites in the surface of the hosts cell
2- penetration: viral particles is taken into the cell and sometimes it involves endocytosis
3- uncoating: separation of the viral nucleic acid from the capsid and now the virus is non-effective
4- eclips/replication: viral particles present as small non infective subunit within the host cell and virus is not visible
5- assembly; newly synthesised viral genomes and capsid proteins come together to form new
6- release:
-non-envelope viruses generally lyse or burst the cell
- envelope viruses leave the host by budding process resembling exocytosis

Question 12

the synthetic and replicative phase of the virus is highly – and extremely — at a — level

Answer 12

• regulated
• complex
• molecular

Question 13

— control over the hosts sythetic and metabolic machinery depending on —-

Answer 13

• free viral nucleic acid
• virus genome dna/rna

Question 14

enters the hosts cells nucleas and replication the nuclease and transpiration in the nuclease

Answer 14

dna viruses except poxvirus

Question 15

is replicated in the cytoplasm and transprption in the cytoplasm

Answer 15

rna viruses except retrovirus

Question 16

the viral nucleic acid alters the — of the host cells and trusts to synthesise the building block for new viruses

Answer 16

genetic expression

Question 17

the — becomes a message for sythesizing the viral protein for translation

Answer 17

rna

Question 18

viruses w — sense rna molicles contain the correct message for traslation into proteins but —- need to be converted into —

Answer 18

• +ve
• -ve convert into +ve

Question 19

in the next phase the new rna is synthesised by using

Answer 19

host nucleotide, proteins for the capsid, spikes, viral enzymes are syethised on the hosts ribosomes using its amino acids

Question 20

rna viruses replication takes place in the — and are placed into — depending on the —

Answer 20

cytoplasm and are placed into 4 groups depending on their mode of replication

Question 21

the —- ( aka whether or not it can be used directly by ribosomes to make proteins) of single strand rna largely determines the replicative mechanism and —

Answer 21

polarity and the genetic material aka whether its single or double stranded

Question 22

rna virus uses the town — enzymes to create copies of themselves

Answer 22

rna replicase

Question 23

rubella virus uses

Answer 23

rna polymerase and is membrane fusion

Question 24

the shape of the rubella virus — and it causes —- but —- is possible

Answer 24

• icosahedral single strand of rna
• red rash and fever rubella, German measles and heart failure in infected infant
• vaccination

Question 25

Viruses by their nature interrupt — and may cause — or —-

Answer 25

• normal cell cycle
• asymptomatic
• malignt or benign growth

Question 26

viral virulence can infect one species like — or different species of mammals w broad ranges

Answer 26

• small box
• rabies virus

Question 27

enzymes produced which erode the cell wall (bacteria)/ cell membrane and cause the cell to rupture;
these are terme

Answer 27

lytic or virulent viruses

Question 28

here viral DNA/RNA becomes incorporated into the genome of the cell and coexists with the cell;

Answer 28

temperate or lysogenic

Question 29

viruses may have both —- and — and eventually — becomes activated into — phase

Answer 29

• lytic and lysogenic
• lysogenic to lytic phase

Question 30

Viral DNA incorporated into bacterial DNA is called a

Answer 30

prophage

Question 30

lysogenic infection steps:

Answer 30

• phages can be spread to infect bacteria
• viral dna is incortated into bacterias dna called prophage
• bacteria can divide by fission copying the provirus
• when its activated it can replicate new viral particles to make more phages and enter lytic stage

Question 31

treatment of viruses is — because they use ——

Answer 31

difficult, they use the hosts own processes for propagation
viral chemotherapy: New therapies involve compounds such as
a) Acyclovir, in cold sore creams on Herpes virus ( it won’t cure it but cam lessen the outbreaks)
b) Interferon, used in treatment of AIDS
Early detection and prevention are the current approaches to treatment of viral diseases

Question 32

true or false: viruses can be responsible for human cancer

Answer 32

true

Question 33

Human Papillomavirus are

Answer 33

• dna virus
• warts ( trees like warts can develop an infection and weakened the immune system )
  -non malignant tumor

Question 34

sub viral particles:
infectious agents smaller by an order of magnitude than viruses have been identified in recent years:

Answer 34

• viroids
• prions

Question 35

Short single strands of RNA;
Circular structures of 250-400 nucleotides
Don’t code for any proteins;
No protective coat (unlike viruses)
Copied by the host RNA polymerase;
Infect plant cells.

Answer 35

viroids

Question 36

prions

**

Answer 36

Prion means - ‘Proteinaceous infectious particle’;
Even smaller than a viroid and consisting of just a protein of 208 Amino Acids;
Only infectious agent without nucleic acid;
Induces normal PrP proteins to misfold thus forming another prion

Question 36

— induce formation of an — fold ie. the protein polymerises into an aggregate consisting of tightly packed beta sheets

Answer 36

• prions
• an amyloid

Question 37

prions are involved in:

Answer 37

-‘Spongioform Encephalopathies’ with
long incubation periods (Previously known as ‘Slow virus’ )
- infects animals like:
- scrapie in sheep
- BSE : bovine sponigferom encephalopathy in cattle aka mad cow disease
- prions in humans:
- kuru : a spongiofrom encephalophy caused by the consumption of infected human brain tissue which affects the brain and nerves
- CJD: Creutzfeldt-Jacob Disease)
New variant CJD [vCJD] in Britain appears to have crossed the species barrier from cattle.