BIOC20 FINAL EXAM QUESTIONS WITH COMPLETE
VERIFIED ANSWERS
Negative strand RNA genomes
Single stranded
Cannot be directly translated
To make proteins, the negative strand must be used to make a complimentary positive
strand
How to convert negative strand to positive strand?
Original genome (negative sense strand) -> conversion using RNA dependent RNA
polymerase -> complimentary positive sense strand
Positive stranded RNA virus
Does not need an RNA polymerase, can be directly translated and can produce RNA
and make RNA
What codes for the Viral RNA polymerase?
The Negative stranded RNA virus codes for their own RNA polymerase (they do NOT
use the cell's polymerase bc it can only read DNA)
How does the RNA polymerase get created?
Negative strand is accompanied by the RNA polymerase which reads the negative
strand and creates the positive strand. The positive strand can code for multiple viral
proteins (including the RNA polymerase) as well as more complimentary negative
strands
,Ribonuceleo-protein complex
Negative strand RNA genome + RNA polymerase (RNA polymerase is made up of diff
components)
Negative Stranded RNA Viral Families (list 5)
Paramyxoviruses
Rhabdoviruses
Filoviruses
Bunyaviruses
Influenza viruses (umbrella virus)
Influenza Virus Proteins (individual segments)
Entire genome exists as 8 individual segments
Each segment codes for a different protein
What does the RNA polymerase complex consist of?
Complex consists of PA, PB1, and PB2
What do Influenza Virus Genome segments 1,2 and 3 code for?
Segments 1,2,3 code for the components that make up the RNA polymerase complex
What does Segment 4 code for?
Genome segment 4 corresponds to hemaglutinin (one of the enveloped proteins)
What does Segment 5 code for
nucleocapsid proteins
What does segment 6 code for
Neuraminidase (another viral protein)
What does segment 7 code for
,2 diff proteins:
1) M2 (ion channel)
2) M1 matrix protein
What does segment 8 code for?
NS2 proteins
Is the Influenza virus enveloped or non enveloped?
Influenza is an enveloped virus
What is a nucleocapsid in Influenza?
When the genome binds to the capsid proteins. However, for influenza, we refer to the
capsid protein itself as a nucleocapsid protein (NP)
How does Influenza enter a cell
Dock at target cell and is taken in by vesicles that pinch inwards from plasma
membrane. Now the virion is within an endosome and as the endosome matures, the
enveloped virus fuses with the endosomal membrane to dump its nucleocapsid out into
the cytoplasm
How does Influenza fusion work?
Viral envelope and envelope protein attached to envelope -> protein undergoes
conformational change after being exposed to acidic environment -> fusion peptides are
exposed and inserted into the endosomal membrane -> more viral envelope proteins
cluster together and fuse as well -> jack-knife confirmation occurs (proteins bend and
pull in endosomal membrane -> creation of fusion channel for a nucleocapsid to enter
Which protein mediates the fusion between the viral envelope and the endosomal
membrane?
, The hemagglutinin protein
What are the names of the Hemagglutinin (HA) protein domains?
2 domains:
HA1 domain
HA2 domain
what is the function of the HA1 domain?
responsible for docking (has a sialic acid binding domain)
•Domain binds to the sialic acid on receptors on the plasma membrane
•Nucleocapsid is taken in by the vesicles that pinch in from the plasma membrane
•Now in endosome and waiting for fusion to occur
What is the function of the HA2 domain
responsible for fusion
•Activated when cleavage occurs between HA1 and HA2
Allows for HA2 to insert itself into the endosomal membrane
what are the three steps of membrane fusion
1) binds to cell receptor
2) Enters the endosome
3) N-terminus of HA2 undergoes conformational change
how does the HA proteins become a part of the influenza viral envelope?
In Influenza, viral envelope proteins go to the plasma membrane to wait for a
nucleocapsid to come so it may pinch off
It arrives at the plasma membrane via our secretory route (ER to Golgi to plasma
membrane)
VERIFIED ANSWERS
Negative strand RNA genomes
Single stranded
Cannot be directly translated
To make proteins, the negative strand must be used to make a complimentary positive
strand
How to convert negative strand to positive strand?
Original genome (negative sense strand) -> conversion using RNA dependent RNA
polymerase -> complimentary positive sense strand
Positive stranded RNA virus
Does not need an RNA polymerase, can be directly translated and can produce RNA
and make RNA
What codes for the Viral RNA polymerase?
The Negative stranded RNA virus codes for their own RNA polymerase (they do NOT
use the cell's polymerase bc it can only read DNA)
How does the RNA polymerase get created?
Negative strand is accompanied by the RNA polymerase which reads the negative
strand and creates the positive strand. The positive strand can code for multiple viral
proteins (including the RNA polymerase) as well as more complimentary negative
strands
,Ribonuceleo-protein complex
Negative strand RNA genome + RNA polymerase (RNA polymerase is made up of diff
components)
Negative Stranded RNA Viral Families (list 5)
Paramyxoviruses
Rhabdoviruses
Filoviruses
Bunyaviruses
Influenza viruses (umbrella virus)
Influenza Virus Proteins (individual segments)
Entire genome exists as 8 individual segments
Each segment codes for a different protein
What does the RNA polymerase complex consist of?
Complex consists of PA, PB1, and PB2
What do Influenza Virus Genome segments 1,2 and 3 code for?
Segments 1,2,3 code for the components that make up the RNA polymerase complex
What does Segment 4 code for?
Genome segment 4 corresponds to hemaglutinin (one of the enveloped proteins)
What does Segment 5 code for
nucleocapsid proteins
What does segment 6 code for
Neuraminidase (another viral protein)
What does segment 7 code for
,2 diff proteins:
1) M2 (ion channel)
2) M1 matrix protein
What does segment 8 code for?
NS2 proteins
Is the Influenza virus enveloped or non enveloped?
Influenza is an enveloped virus
What is a nucleocapsid in Influenza?
When the genome binds to the capsid proteins. However, for influenza, we refer to the
capsid protein itself as a nucleocapsid protein (NP)
How does Influenza enter a cell
Dock at target cell and is taken in by vesicles that pinch inwards from plasma
membrane. Now the virion is within an endosome and as the endosome matures, the
enveloped virus fuses with the endosomal membrane to dump its nucleocapsid out into
the cytoplasm
How does Influenza fusion work?
Viral envelope and envelope protein attached to envelope -> protein undergoes
conformational change after being exposed to acidic environment -> fusion peptides are
exposed and inserted into the endosomal membrane -> more viral envelope proteins
cluster together and fuse as well -> jack-knife confirmation occurs (proteins bend and
pull in endosomal membrane -> creation of fusion channel for a nucleocapsid to enter
Which protein mediates the fusion between the viral envelope and the endosomal
membrane?
, The hemagglutinin protein
What are the names of the Hemagglutinin (HA) protein domains?
2 domains:
HA1 domain
HA2 domain
what is the function of the HA1 domain?
responsible for docking (has a sialic acid binding domain)
•Domain binds to the sialic acid on receptors on the plasma membrane
•Nucleocapsid is taken in by the vesicles that pinch in from the plasma membrane
•Now in endosome and waiting for fusion to occur
What is the function of the HA2 domain
responsible for fusion
•Activated when cleavage occurs between HA1 and HA2
Allows for HA2 to insert itself into the endosomal membrane
what are the three steps of membrane fusion
1) binds to cell receptor
2) Enters the endosome
3) N-terminus of HA2 undergoes conformational change
how does the HA proteins become a part of the influenza viral envelope?
In Influenza, viral envelope proteins go to the plasma membrane to wait for a
nucleocapsid to come so it may pinch off
It arrives at the plasma membrane via our secretory route (ER to Golgi to plasma
membrane)
