How does germline gene therapy work?
• how is the functional allele delivered to the cell nucleus?
• is this a more short-lived or long-lived solution? why?
• what are 2 ethical issues with this method of gene therapy?
• the functional allele is inserted into either the gametes or the zygote, in vitro, will
involved engineered sperm, egg or zygote, meaning this allele will passed onto
every cell in the genome & future offspring
• long-lived as offspring will inherit the functional allele too
• ethical issues:
o 'designer babies' - what is actually life-limiting enough to give gene
therapy to - subjective
o acts as a permanent modification to the human genome, raises ethical,
moral, religious issues. bc future implications are highly unpredictable -
could create a new human disease or interfere with natural human
evolution
How does somatic gene therapy work?
• how does it actually overcome the genetic disease?
• how is the functional allele delivered? (which is more popular and why?)
• is this a more short-lived or long-lived solution? why?
• the faulty gene is not replaced, but instead a fucntional allele is inserted into the
nucelus, so that the functional polypeptide the indiviual may require, is still
produced. e.g type 1 diabetes - functional allele producing insulin
• functional allele can enter via liposomes (plasmids surrounded in a fatty layer).
can also enter via non-infectious virus vectors, however they still have the
antigens on them, so the body attacks them, so has low success rate
• the treatment is short-lived and needs regular repeats, bc the cells will
eventually die and not pass on the plasmid DNA.
• restricted to actual patient
What is gene therapy? State the 2 types.
Gene therapy = any therapeutic technique where a functional (non-genetic-disease-
causing) allele of a particular gene is placed into a human cell nucleus, in order to
remove/prevent the genetic disease
(but not the actual faulty allele).
2 types;
• somatic cell gene therapy
• germline cell gene therapy
What kind of marker genes are often used in genetic engineering and why?
, Plasmids are chosen with genes for specific antibiotic resistance. These act as the
genetic markers.
This is bc before the bacteria is mass produced; they have to identify which bacteria are
transgenic (actually took up the recombinant plasmid). By adding antibiotics to the
mixture, you kill off any non-transgenic bacteria, since they don't have the resistant-
marker gene.
Using human insulin gene as an example, describe how genetic engineering works,
from obtaining the desired gene to being able to extract your product.
Genetic Engineering:
1. extract mRNA used to synthesis insulin proteins, from the nucleus of a beta cell
in the Islets of Langerhans (it will be abundant as this is the cell's main purpose)
2. isolate the mRNA, using free nucleotides and reverse-transcriptase to remake
the DNA (cDNA - single stranded). RNAase destroys the original mRNA and DNA
polymerase will use free nucleotides to build the second, complementary strand
of the cDNA, forming a double-strand DNA with the desired gene. This DNA is the
same as the original DNA that coded for insulin proteins in the beta cells. this
one lacks introns tho bc they were spliced out.
3. add restriction enzymes to create sticky ends. This involves cutting/cleaving the
ends of the DNA, producing overhanging single stranded fragments. Like so:
a.
4. amplify the desired gene (that has sticky ends now) using PCR
5. extract a plasmid (used as a vector for the gene) from a bacterial cell. use
restriction enzymes to cut the plasmid while giving it complementary sticky ends
to our desired genes
• how is the functional allele delivered to the cell nucleus?
• is this a more short-lived or long-lived solution? why?
• what are 2 ethical issues with this method of gene therapy?
• the functional allele is inserted into either the gametes or the zygote, in vitro, will
involved engineered sperm, egg or zygote, meaning this allele will passed onto
every cell in the genome & future offspring
• long-lived as offspring will inherit the functional allele too
• ethical issues:
o 'designer babies' - what is actually life-limiting enough to give gene
therapy to - subjective
o acts as a permanent modification to the human genome, raises ethical,
moral, religious issues. bc future implications are highly unpredictable -
could create a new human disease or interfere with natural human
evolution
How does somatic gene therapy work?
• how does it actually overcome the genetic disease?
• how is the functional allele delivered? (which is more popular and why?)
• is this a more short-lived or long-lived solution? why?
• the faulty gene is not replaced, but instead a fucntional allele is inserted into the
nucelus, so that the functional polypeptide the indiviual may require, is still
produced. e.g type 1 diabetes - functional allele producing insulin
• functional allele can enter via liposomes (plasmids surrounded in a fatty layer).
can also enter via non-infectious virus vectors, however they still have the
antigens on them, so the body attacks them, so has low success rate
• the treatment is short-lived and needs regular repeats, bc the cells will
eventually die and not pass on the plasmid DNA.
• restricted to actual patient
What is gene therapy? State the 2 types.
Gene therapy = any therapeutic technique where a functional (non-genetic-disease-
causing) allele of a particular gene is placed into a human cell nucleus, in order to
remove/prevent the genetic disease
(but not the actual faulty allele).
2 types;
• somatic cell gene therapy
• germline cell gene therapy
What kind of marker genes are often used in genetic engineering and why?
, Plasmids are chosen with genes for specific antibiotic resistance. These act as the
genetic markers.
This is bc before the bacteria is mass produced; they have to identify which bacteria are
transgenic (actually took up the recombinant plasmid). By adding antibiotics to the
mixture, you kill off any non-transgenic bacteria, since they don't have the resistant-
marker gene.
Using human insulin gene as an example, describe how genetic engineering works,
from obtaining the desired gene to being able to extract your product.
Genetic Engineering:
1. extract mRNA used to synthesis insulin proteins, from the nucleus of a beta cell
in the Islets of Langerhans (it will be abundant as this is the cell's main purpose)
2. isolate the mRNA, using free nucleotides and reverse-transcriptase to remake
the DNA (cDNA - single stranded). RNAase destroys the original mRNA and DNA
polymerase will use free nucleotides to build the second, complementary strand
of the cDNA, forming a double-strand DNA with the desired gene. This DNA is the
same as the original DNA that coded for insulin proteins in the beta cells. this
one lacks introns tho bc they were spliced out.
3. add restriction enzymes to create sticky ends. This involves cutting/cleaving the
ends of the DNA, producing overhanging single stranded fragments. Like so:
a.
4. amplify the desired gene (that has sticky ends now) using PCR
5. extract a plasmid (used as a vector for the gene) from a bacterial cell. use
restriction enzymes to cut the plasmid while giving it complementary sticky ends
to our desired genes
