lecture 18 cmv and viroids Flashcards
All of the following describe a method of introducing Cucumber Mosaic Virus into a healthy plant EXCEPT….
Mechanical inoculation
Insect feeding
Grafting an infected branch
Infection of seeds
Watering with a virus containing solution
Watering with a virus containing solution
Which of the following statements about cucumber mosaic virus is FALSE?
It can cause asymptomatic infections in some plants.
It has an enveloped helical nucleocapsid.
It is transmitted by aphids.
Its genome is composed of positive-strand RNA.
It has a wide range of host species that it can infect.
It has an enveloped helical nucleocapsid.
Which of the following describes the structures of the genomic RNA segments from cucumber mosaic virus?
They have a 5’ cap and a 3’ poly A tail.
They have a 5’ cap and a 3’ terminal tRNA-like structure.
They have a 5’ IRES and a 3’ poly A tail.
They have a protein covalently bound to the 5’ end and a 3’ poly A tail.
They have a 5’ phosphate and a 3’ terminal tRNA-like structure.
They have a 5’ cap and a 3’ terminal tRNA-like structure.
Which of the following describes a feature of plant viruses, like cucumber mosaic virus, that is rare or absent in animal viruses?
Viral genomic RNA has a 5’ cap.
Segmented genomes are each packaged into a single virion.
Viral genomes are composed of ssRNA with a negative sense.
Segmented genomes are each packaged into separate virions.
Viral particles are transmitted to new hosts via an insect vector.
Segmented genomes are each packaged into separate virions.
Which of the following characteristics of the cucumber mosaic virus influences the aphid species that can transmit the virus?
The sequence of the IRES at the 5’ end of the genomic RNA.
The replication efficiency of the RNA-dependent RNA polymerase.
The sequence of the 3’ end of the viral genomic RNA.
The specificity of binding to the host cell receptor.
Amino acid sequence of the coat protein.
Amino acid sequence of the coat protein.
Which of the following describes the first step in the replication cycle of the cucumber mosaic virus?
Copying of viral genome into dsDNA.
Synthesis of minus-strand copies of the genome.
Translation of the genome into protein.
Synthesis of plus-strand copies of the genome.
Copying of the viral genome into mRNA.
Translation of the genome into protein.
What is the role of the plasmodesmata in the replication of cucumber mosaic virus?
They are the sites of viral replication inside of plant cells.
They allow movement of virus genomes between neighboring cells.
They are the sites of entry of capsids into the host cell.
They allow release of progeny virions from host cells.
They are involved in assembly of progeny virions.
They allow movement of virus genomes between neighboring cells.
Plant defenses against RNA viruses involved which of the following?
RISC
Dicer
Host RNA-dependent RNA polymerase
All are correct.
siRNAs
All are correct.
Which of the following statements about satellite RNAs found in cucumber mosaic virus infections is FALSE?
They are small linear RNA molecules.
They can increase the symptoms produced by cucumber mosaic virus.
They encode several functional proteins.
They are packaged into cucumber mosaic virus capsids.
They require a cucumber mosaic virus for replication.
They encode several functional proteins.
Which of the following proteins from cucumber mosaic virus acts at the RNA-dependent RNA polymerase?
Protein 2b
Protein 1a
Protein 2a
Movement Protein
Coat Protein
Protein 2a
Which of the following is NOT a type of infectious RNA that can cause disease?
Viroid
Satellite RNA
Viroid-like plant satellite RNA
Hepatitis delta virus
Prion
Prion
Which of the following is a major difference between the group A and the group B viroids?
Whether they produce a protein or not.
Whether they affect the RNAi pathway or not.
Whether they have a self-cleaving RNA or not.
Whether they infect animals or plants.
Whether they replicate in the endoplasmic reticulum or not.
Whether they have a self-cleaving RNA or not.
The typical structure of the genome of a viroid is described as?
Circular singled-stranded RNA of 250-400nts.
Circular double-stranded DNA of 3000-4000bp.
Linear single-stranded RNA of 500-1000nts.
Linear double-stranded RNA segment of 500-1000bps.
Circular double-stranded RNA of 400-800bp.
Circular singled-stranded RNA of 250-400nts.
What is surprising about the observation that a cellular RNA polymerase copies the viroid genome?
RNA polymerases don’t usually synthesize DNA.
RNA polymerases don’t usually initiate synthesis from a protein primer.
RNA polymerases usually require a pre-existing RNA primer.
RNA polymerases usually transcribe from a DNA template.
RNA polymerases are not found in the cytoplasm of the host cell.
RNA polymerases usually transcribe from a DNA template.
Which of the following is NOT thought to be a mechanism by which viroids cause disease in their plant hosts?
By causing the degradation of cellular mRNAs via the RNAi pathway.
By basepairing to an important cellular RNA, preventing its function.
By interfering with mRNA splicing because they resemble a cellular snRNA.
By inhibiting the machinery that exports mRNAs out of the nucleus.
By activating the dsRNA induced protein kinase.
By inhibiting the machinery that exports mRNAs out of the nucleus.
