Viruses and Eukaryotes Flashcards
Extracellular form of a virus
Virus particle
Infectious virus particle
virion
Viral genomes can have either
DNA or RNA genomes/ circular or linear
Can viruses have SsRNA/dsRNA same for DNA?
Yes
Viruses are grouped based on
the hosts they infect
capsid
protein shell around genome
capsomer
subunit of the capsid
Nucleocapsid and enveloped virus
-complete complex of nucleic acid
virus that has additional layers around nucleocapsid
Helical symmetry vs icosahedral symmetry
- Rod shaped viruses, length determined by length of nucleic acid.
- Spherical viruses
Enveloped viruses have
lipid bilayer with embedded proteins ad glycoproteins are encoded by the viral genome
Glycoproteins make ? with host cells
Initial contact
Name the enzymes critical to infection
Lysozymes, nucleic acid polymerases (Reverse transcriptase), and neuraminadases (enzymes that cleave glycosidic bonds to free the virus.)
What is analogous to the bacterial colony and used to measure virus infectivity?
Plaque assays
Plaques?
Clear zones that develop on lawns of host cells, result from infection by a single virus
Phases of rial replicatio
Attachment Entry Synthesis Assembly Release
Example the phases of the one-step growth curve
Eclipse- genome is replicated and proteins are translated
Maturation-packaging of nucleic acid in capsids
Latent Period- eclipse + maturation
Release - cell lysis, budding, or excretion
Burst size
of virons released.
Attachment of virion to host is
highly specific and requires complementary receptors on the surface.
Receptors? What are they
carry out normal functions for cell,
include proteins, carbs, glycoproteins, lipids, lipoproteins, or complexes.
What bacteria effects E. Coli?
Bacteriophage- T4
Name the viral defenses of eukaryotes/bacteria/
Eukaryotes- RNA interference/immune defense
Bacteria- restriction-mod system, DNA destruction system (only effective against DNA virus)
, restriction enzymes (cleave DNA) at specific sequences.
AND CRISPR- against viruses,
Once a host has been infected, what must happen?
Virus-specific proteins must be synthesized and new copies of the viral genome must be made.
mRNA first.
Viral genome is the template for
the viral mRNA
in some viruses, viral RNA genome itself is the mRNA.
What are in the virion
Essential transcriptional enzymes such as RNA replicase.
Genome replication
many different schemes.
single stranded DNA/RNA virus
mRNA is in the plus configuation while its complement is in its minus config.
+ strand RNA virus
single strand RNA GENOME with sam orientation as its mRNA
- strand RNA virus
single stranded RNA GENOME WITH COMPLEMENTARY orientation to its mRNA.
Neg strand RNA and doubled stranded RNA viruses need
RNA-dependents RNA polymerase to make mRNA
Smalll DNA viruses use ?
DNA polymerase
t4 encodes?
is first replicated as?
primases, helicases, and 8-protein DNA replisome complex.
as a unit then forms concatemer (several genomic units combined)
circular permuation
feature of many virus genomes where same genes are arranged in differrent orders.
Terminally redundant
some DNA sequences duplicated on both ends.
How long does virion synthesis take? What does it release?
- 30min
- new virions lysed from cell.
Early, middle, late proteins of T4 genome
see notes
During transcription and translation of T4 bacteriophage, what happens?
The early, middle/late proteins
and the T4-specific proteins modify host RNA polymerase specificity to recognize only phage promoters.
Host transcription gets shut down.
explain the three stages of packaging the t4 genome
THE VIRION ASSEMBLY and the release
see notes
The genome is pumped into the head under pressure using what
ATP
the best-studied bacteriophages infect what bacteria
and most contain what genomes?
enteric
most contain dsDNA genomes
Virulent mode
lyse and kill host
Temperate mode
Replicate their genome wihtout killing
Temperate viruses can undergo a
a different life cycle resulting in the stable genetic relationship within the host, but can also kill sounds through lytic cycle
Lysogeny
state where most virus genes not expressed and virus genome (prophage) is replicated along with host chromosome
Lysogen
bacteria containing a prophage
ANIMAL viruses contain…
all known modes of viral genome replication
There are more kinds of ? animal viruses than bacterial viruses.
Enveloped
as animal viruses leave host cell,
they can remove part of host cells lipid bilyar for their envelope.
What are the consequences in virus infection of animal cells.?
lysis of cells, persistent infections, latent infections, transformation (normal to tumor)
Retroviruses
RNA viruses, that replicate via a DNA intermediate
are an enveloped and have enzymes: reverse transcriptase, integrase, protease
Process of replication of retroviruses
entrance into the cell and removal of viron envelope
reverse transcription of one of the two RNA genomes
integration of retroviral DNA into host genome using integrase enzyme
transcription of virus mRNA from viral DNA
assembly and packaging of genomic RNA after its transcribed then budding of envelopes virions, released from cell
Prions
infectious proteins
causes DNA in animals
Host cell has native form of prion protein found in healthy animals
mad cow disease
infectious prion disease
transmitted between animals or humans
sporadic prion disease
random misfolding in uninfected indv
inherited prion disease
mutation in the prion gene yields a protein that changes more often into a disease-causing form.
Mitochondria and Hydrogenosome
specialize in chemotrophic energy metabolism
the mitochondria is for respiration in oxidative phosphorylation
hydrogenosome lack the CAC cycle AND HAS NO GENOME OF ITS OWN
oxidizes pyruvate to hydrogen carbon dioxide in acetate and is found in trichomonas
Thylakoids
flattened membrane disks
Stroma
Lumen of chloroplast
Stroma contains LARGE AMOUNTS
RubisCO
Key enzime in calvin cycle?
Rubisco
the relationship between the 18s rRNA genes is
LESS strong for eukaryotes then 16s RRNA genes are for prokaryotes
Diplomonads
have two nuclei of equal size, have my toes ohms that degenerate mitochondria, Giardia is the cause of giardiasis a common waterborne disease
Parabasalids
Lack mitochondria but have hydrogenosomes for anaerobic metabolism
living intestinal and urogenital tract
trichomonas vaginalis
The two key genera refer diplomonads and parabasalids are
Giardia and trichomonas
Euglenozoans key genera
Trypanosoma and Euglena
Group of euglenozoans are
Kinetoplastids
