What are the functions of viroids?
Abstract. Mature viroids consist of a noncoding, covalently closed circular RNA that is able to autonomously infect respective host plants. Thus, they must utilize proteins of the host for most biological functions such as replication, processing, transport, and pathogenesis.
What is the genetic material of a viroid?
ribonucleic acid (RNA)
Like some viruses, viroids are little more than a strand of genetic material called ribonucleic acid (RNA).
What are the characteristics of viroids?
Characteristic Features Of Viroids Viroids contain only RNA. These are known to be smaller in size and infect only the plants. These are among the smallest known agents causing infectious disease. Viroids are the species of nucleic acid with relatively low molecular weight and a unique structure.
Do viroids have genetic information?
Viroids or ribozymes are composed of naked closed circular RNA with zero genes, i.e., they do not code for triplets for amino acids as we know them on Earth. They not contain genetic, i.e., coding, but structural information [14]. The RNAs exhibit structure-mediated functions.
Do viroids produce proteins?
Viroids are plant pathogens: small, single-stranded, circular RNA particles that are much simpler than a virus. They do not have a capsid or outer envelope, but like viruses can reproduce only within a host cell. Viroids do not, however, manufacture any proteins, and they only produce a single, specific RNA molecule.
What is difference between virion and viroid?
Viruses (Virus particles or virions) are usually units consisting of nucleic acids and coat proteins called capsids. Viroids consist only of RNA, i.e. they contain no protein at all.
Do viroids have DNA as genetic material?
All viroids have RNA as their genetic material. Moreover, viroids are entities which are smaller than viruses and affect only plants.
What is the genetic material in bacteriophage?
Bacteriophage have either DNA or RNA as their genetic material, in either circular or linear configuration, as a single- or a double-stranded molecule.
What is viroids and mention its significance?
Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective economic importance to humans varies widely.
What are viroids composed of?
Viroids are infectious agents composed solely of circular single-stranded RNA which folds over on itself to form some double stranded regions. These are catalytic RNAs (ribozymes).
Do viroids have protein coat?
How do viroids reproduce?
Viroid replication proceeds through an RNA-based rolling-circle mechanism with three steps that, with some variations, operate in both polarity strands: i) synthesis of longer-than-unit strands catalyzed by either the nuclear RNA polymerase II or a nuclear-encoded chloroplastic RNA polymerase, in both instances …
What is the function of viroids?
Some viroids are ribozymes, having catalytic properties that allow self-cleavage and ligation of unit-size genomes from larger replication intermediates.
What is a viroid made of?
67. Sanger H.L., Klotz G., Riesner D., Gross H.J., Kleinschmidt A.K. Viroids are single-stranded covalently closed circular RNA molecules existing as highly base-paired rod-like structures. Proc. Natl. Acad.
What is the role of viroids in plant pathogenesis?
Unlike plant viruses which produce movement proteins, viroids are entirely passive, relying entirely on the host. This also is useful in the study of RNA kinetics in plants in general, pathogenic or not. There has long been uncertainty over how viroids induce symptoms in plants without encoding any protein products within their sequences.
Do viroids code for any proteins?
Although viroids are composed of nucleic acid, they do not code for any protein. The viroid’s replication mechanism uses RNA polymerase II, a host cell enzyme normally associated with synthesis of messenger RNA from DNA, which instead catalyzes “rolling circle” synthesis of new RNA using the viroid’s RNA as a template.