acellular life Flashcards
branch of biology deals with viruses
virology
characteristic of viruses(4)
1.GENOM (rna or dna)
2. protein coat(capsid)
3.reproduce only in living cell
4. lack organelles
why are viruses called Obligate intracellular parasites.
virus affecting a cell have control over the living cell
viruses destroyed by?
uv radiations
complete mature infectious virus called?
Virion
capsid made up of protein subunits known as?
capsomeres
the number of_____ is characteristic of a particular virus
capsomeres
who first discovered viruses and which method was used?
Iwanowski filtration.
bacteria couldnt pass through while agents responsible for rabies could.
who discovered that agent causing tobacco mosaic diseases was filterable?
A. charles chamberland
B. W.M stanley
C. Ivanowski
D. Edward jenner
ivanowski.
who was succesful in crystallising the tobacco mosaic virus
Stanley
what are prions?
infectious viral proteins that are self replicating. Cause mad cow adisease
what are viriods?
smallest infectious pathogens known.
composed of short single strand of RNA
double stranded dna virus
Poxviruses
single stranded rna viruses
togavirus(rubella virus), retrovirus, influenza virus
Single stranded DNA virus
Parvoviruses(mild rash)
Double stranded RNA viruses
Reoviruses(diarrhea)
how many known Plant viruses?
More than 2000 known.e.g T.M.V
animal virus that cause cancer in animals
Rous Sarcoma Virus
virus causing measles and mumps
Paramoxyvirus
virus causes small pox
pox virus
Bacteriophage virus function
parasitize the bacterial cells.
e.g Tadpoe virus T2 and T4
size of viruses as compared to bacteria
10-1000x smaller.
model viruses e.g
bacteriophage(bacteria eater)
flu virus
HIV
structure of bacteriophage
.head(capsid)
.collar
.tail (contains lysozyme which digests bacterial cell wall)
. tail fiber( 6 fibers used to attach)
bacteriphage life cycle steps
LYTIC CYCLE
1. attachment of virus to receptors
2.entry into the bacterial cell
3.Transcription of viral dna
4. replication
5. assembly of new parts
6. lysis and release
lysogenic cycle
attachment and entry of genetic material(same as lytic cycle)
.viral dna binds to bacterial dna.
. bacterial cells divide by binary fission
.transferred to daughter cells.
influenza virus structure
exists in 3 forms
single strand RNA
capsid have spikes for attachment
HIV structure
enveloped with spikes
viral capsid
reverse transcriptaseviral rna (two single strands)
herpes virus causative
herpes simplex which is dna enveloped.
vascular lesions(zakham) in layers of mouth lips skin
mumps disease
(Cause and symptoms)
caused by paramoxyviruses
enveloped rna virus
symptoms; painful swelling of salivary gland
influenza
enveloped rna
symptoms;fever cold sneezing
measles
caused by paramyxoviruses
rna enveloped
fever and rash
polio
rna IN SPHERICAL CAPSID
symptoms; inflammation of nervous system and paralysis
Retroviruses description and types(2)
ssRNA virus AND contains Reverse transcriptase (rna to dna)
all retroviruses rna but NOT vice versa
.host specific e.g HIV
.non host specific: infect any host
characteristics of retroviruses
- spherical
- enveloped
- size 100nm
- responsible for aids
symptoms of HIV
.rare vascular cancer
.severe pneumonia
.dementia
.loss of immunity
.swollen lymph nodes
.fever.
.septicimia (blood infection)
.kaposi sarcoma (skin cancer)
hiv infects which wbc
helper T lymphocytes.
tranmission of hiv
breastfeeding
blood transfusions
contaminated syringes
sexual contact
passed genetically
life cycle of HIV
virion (mature virus) attaches to CD4 receptors on t helper lymphocytes
virion enters and uncoats in cytoplasm
reverse transcriptase uses viral rna to make double strand DNA
DNA enters nucleus and into host chromosome.[PROVIRUS]
proviral dna—->RNA——-> proteins
what is hepatitis (hepatic)
inflammation of liver due to viral infections, toxic agents or drugs
hepatitis symptoms
jandice (yarkaan)
abdominal pain (pait dard)
liver enlargement
fatigue
fever
hepatitis A causative agent and types
HAV, A NON ENVELOPED RNA VIRUS
two types
.Acute or mild
.Chronic
hepatitis A mode of transmission and symptoms
.Faeces of infected person
.contaminated water
symptoms;
black urine
jaundice
loss of apetite
fatigue
hepatitis B (serum hepatitis)
mode of transmmission/causative agent
HBV, DNA ENVELOPED
transmission;
mother to child during birth or feeding
sexual contact
blood serum
which hepatitus known as infusion hepatitus and infectious respectively
C & A
Hepatits C
mode/causative
HCV DNA* ENVELOPED
.blood transfusion
.mother to child
.sexual contact
which hepatitis is defective
D
