Pharmaceutical Drugs and Dosage: Biotechnology-based drugs - Review questions answers
Review questions
26.1 The term
gene therapy refers to a method
A. For the treatment or
prevention of disease by allowing the patient’s cells to produce specific
therapeutic proteins
B. For the treatment of
genetic as well as acquired or chronic diseases
C. Which allows
production of therapeutic protein or inhibition of abnormal protein production
D. Which allows somatic
or germ-line cells to produce therapeutic/ reporter proteins
E. All of the above
26.2 Gene
therapy has a great potential because
A. It can control the
intracellular production of a gene product in response to a disease
B. It can restrict the
availability of any gene product to specific sites in the body
C. It can deliver
sustained therapeutic protein levels over a prolonged period
D. Gene expression can
be turned on or off in response to the ben-efits of treatment
E. All of the above
26.3 Define
gene, gene expression, transcription and translation. What are the three basic
components of a gene medicine?
26.4 What is
antisense therapy? What are the types of antisense com-pounds? What are the
types of antisense oligonucleotides?
26.5 What is
RNA interference? Define siRNA, shRNA, and miRNA.
26.6 Describe
the essential feature of a gene expression system.
26.7 Describe the influential factors for the development of
nonviral gene therapy products.
Answers:
26.1 E.
26.2 E.
26.3 Genes
are made of DNA, which contains information about when and how much of which
protein to produce, depending on the functions to be performed. Gene expression
is the process of transcription of DNA into RNA and translation of mRNA into
proteins. The antisense strand of DNA
is used as a template for transcribing enzymes
that assemble mRNA, a process called transcription.
Then, mRNA migrates into the cytoplasm, where ribosomes read the encoded
information, its mRNA’s base sequence and, so doing, string together amino
acids to form a specific protein. This process is called translation.
26.4 Antisense therapy aims at inhibiting the existing but abnormally expressed genes by
blocking the transcription of DNA or translation of mRNA into harmful proteins.
The types of antisense compounds include antisense oligonucleotides (ODNs),
peptide nucleic acids (PNAs), antisense RNA, aptamers, ribozymes, and siRNA.
The types of antisense oligonucleotides include phosphodiester ODNs, phos-phorothioate
ODNs, and methylphosphonate ODNs.
26.5 A gene
expression plasmid is formed of circular double-stranded DNA molecules and
contains a cDNA sequence coding for a ther-apeutic gene and several other
genetic elements, including introns, polyadenylation sequences, and transcript
stabilizers, to control tran-scription, translation, and protein stability.
26.6 The
three important factors in the development of nonviral gene therapy products include
the therapeutic gene, the gene expression system, and the gene delivery system.
A therapeutic gene encodes a specific
therapeutic protein, a gene expression
system controls the functioning of a gene within a target cell, and a gene delivery sys-tem controls the
delivery of the expression system to specific loca-tions within the body.
Plasmid-based gene expression systems contain a cDNA sequence coding for a
therapeutic gene and several other genetic elements, including introns,
polyadenylation sequences, and transcript stabilizers, to control
transcription, translation, and pro-tein stability. The gene delivery system distributes the plasmid to the desired target
cells, after which the plasmid is internalized into the cells. Once inside the
cytoplasm, the plasmid can then translocate to the nucleus, where gene
expression begins, leading to the production of a therapeutic protein through
the steps of transcription (synthesis of RNA from DNA into the nucleus) and
translation (synthesis of protein from mRNA in the cytoplasm).
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