Unit 3 Exam Questions

How can we know that two distantly related bacterial species (or genera) have shared DNA through lateral transfer? In other words, how do we obtain evidence that lateral transfer has occurred in nature?

We know two distantly related bacteria have shared DNA through lateral transfer by sequencing the genomes of bacteria. For example, we know that E.coli has received genes from a Shigella plasmid by sequencing the typical E.coli without the genes from Shigella, the genome of Shigella and the E. coli that contains the Shigella plasmid. From this sequencing, we can see that E.coli that contains genes from Shigella that exactly match the base pairing sequence from Shigella. This unique sequence is not typically seen on E.coli, so the plasmid must have originated from Shigella and E.coli was able to incorporate it.

What are two examples of genes or plasmids that have been shared among bacteria? For each example, say what is known about the function of the gene(s), which bacterium (genus and/or species) donated the DNA, and which bacterium (genus and/or species) received the DNA. [If one of your two examples is from the recent studies presented in lecture, you will receive 3 extra credit points. However, you should still have only two examples.]

A penicillinase producing plasmid has been observed in
Neisseria that likely comes from Streptococcus bacteria. This has allowed for Neisseria bacteria to have resistance to penicillin.

A toxin producing plasmid has been observed in E.coli that likely comes from Shigella bacteria. This allows for E.coli to produce a potent toxin that causes severe illness in humans.

How does lateral DNA transfer affect the evolution of bacteria? How does lateral transfer compare to mutation as an agent of evolution?

Lateral transfer assists in the evolution of bacteria by allowing for large changes such as resistance or virulent genes to be incorporated into the bacterial genome within minutes.
Lateral transfer increases genetic diversity within the population at a quicker rate than mutation as an agent of evolution. Evolution by mutation is slow as it occurs by base pair by base pair changes. Additionally, lateral transfer tends to be more functional because entire sequences are incorporated. Whereas mutations can be random and consequently harm the functionality of the genome.
-mutation can be harmful
-increases versatility
-mutation increases genetic diversity not lateral transfer

Describe the process of transformation where a chromosomal fragment is transferred. Assume that this fragment comes from an unrelated species of bacteria.

During transformation, the donor cell lysis/dies releasing naked DNA into the surrounding environment. This includes chromosomal fragments and entire plasmids. The DNA material will begin to degrade as it is exposed to the open environment. If a bacteria in in close proximity to this occurrence and is not of the same species, it must be competent - able to take up the exogenous DNA. The DNA will pass through the cell wall and membrane of the recipient cell. Because the two bacteria are unrelated, the cell will undergo non homologous recombination (*integration*) to incorporate the exogenous DNA into the recipient genome.

Describe the process of conjugation where a plasmid is transferred.

Conjugation where a plasmid is transferred involves a donor cell with a plasmid allowing conjugation to take place known as an F+ cell and a recipient cell lacking the plasmid for conjugation known as an F- cell. The F+ cell forms a pilus to connect to the F- cell and transfers one strand of the plasmid to the F- cell. DNA polymerase in each cell will then construct the complementary strand and each cell will have the whole plasmid. The two cells will separate and both cells will be F+ cells as the F- cell now contains the plasmid that allows for pilus formation and conjugation.

Describe the process of conjugation where a chromosomal fragment is transferred.

Conjugation where a chromosomal fragment is transferred involves a donor cell known as an F+ cell contains a plasmid making it capable of producing a pilus to transfer DNA to a F- cell that lacks the plasmid. For chromosomal fragments to be transferred, the fertility plasmid will undergo a recombination within the donor cell and become integrated within the genome of the donor cell. The chromosome will then have a F factor. The donor cell will form a pilus and connect to a recipient F- cell. DNA transferred through the pilus will contain F factor and other chromosomal fragments because of the prior recombination event. This new DNA will be incorporated into the recipient cell by recombination. The recipient cell remains F- because it only receives part of the F factor during this type of conjugation.

Describe the process of transduction. Be sure to explicitly point out how DNA is transferred from donor to recipient.

Transduction is the process by which bacterial DNA is transferred from one cell to another via a virus known as a bacteriophage. The virus will infect a bacteria and can enter the lysogenic cycle in which the viral DNA is incorporated into the bacterial DNA, becoming a prophage. The cell may then enter the lytic cycle in which new phages are produced. These new phages being produced after the lysogenic cycle may contain part of the bacterial chromosome from the prior integration in the lysogenic cycle. When the cell lysis, the new phages will be released from the cell, some of which containing bacterial DNA in addition to their viral DNA. When these phages infect a new bacterial cell, they will insert their DNA and the recombinant DNA from the previous bacterial cell. When this newly infected cell goes into the lysogenic cycle of infection, they will receive DNA from the previous bacterial cell infected.

What is one species of pathogenic bacteria that relies on transduction for its virulence. What toxin or function results from expression of the transduced gene(s)?

Clostridium botulinum relies on transduction for its virulence. The incorporation of phage DNA into bacterial DNA of C. botulinum alters the phenotype of the bacteria's DNA by causing the expression of genes to produce highly potent botulinum neurotoxins.

What are the main structural components of all viruses? Describe these components

Viruses are composed of nucleic acids which can be either DNA or RNA that makes up their viral genome and a protein coat. The protein coat, also known as a capsid surrounds the genetic material and the entire component is referred to as a nucleocapsid. ***Some*** can also have an envelope that surrounds the protein coat and this is composed of a phospholipid bilayer.

Describe the structure that is unique to enveloped viruses.

Enveloped viruses have an additional membrane layer composed of a phospholipid bilayer that surrounds their protein coat known as an envelope.

What determines the host range of a virus?

The host range is determined by the proteins found on the capsid of the virus. Their proteins must be able to bind to the receptors of their target cells in order to cause infection. These can be specific to species, tissues or individual cell type dependent on the functionality of their proteins on the capsid of the virus.

Why might some people not consider viruses to be living organisms?

Viruses are incapable of independently reproducing. They require a host to carry out replication because they do not have their own enzymes or structures to facilitate reproduction. They also do not metabolize nutrients or take in energy from their environment to function.

What would be a good description of what a virus is and what it does?

A virus can be described as an obligate intracellular parasite or a pirate. This is because it has to be within a host cell in order to carry out reproduction. When the virus enters the cell, it uses the host cell's enzymes and organelles to produce and assemble its offspring. It also uses the cell as a means to spread its replicated offspring.

What is a possible purpose for the existence of viruses (retroviruses might provide a clue here).

Viruses may exist as a means of natural selection by killing less fit hosts. They may exist as a intermediary to facilitate lateral transfer during transduction and assist in the evolution of bacterial organisms. They also may assist in the evolution of all biological life because of their ability to incorporate into host DNA.

What is the basic scheme of the viral infection cycle? Describe each step.

The basic scheme of viral infection begins when a virus attaches to a host cell. The viral proteins found on the surface of the capsid bind to the receptors of the host cell. Then the virus will penetrate the outer surface of the host cell either by endocytosis or by fusing its envelope with the host cells membrane. Once inside the host cell, the capsid will be uncoated by digestive enzymes either from the virus or the host cell. This will release the nucleic acid of the virus. The host cell will then begin biosynthesis in which the genome of the virus is replicated and then the capsid production begins. During maturation, the new virus particles are assembled to be released. During release, the cell will undergo lysis releasing nucleocapsid viruses or the viruses will bud out of the host cell taking some of the host cell membrane with it if they are enveloped viruses.

Compare the strategies that Ebola and HIV take and relate that to their success in spreading through the human population.

Ebola viruses immediately enter the lytic cycle when they enter a host cell. This causes extensive damage as the cells will undergo lysis in the release of the new virus particles. These new virus particles add to this quick destruction by also entering the lytic cycle immediately. For this reason, they do not spread through the human population effectively because the damage occurs quickly enough for isolation of the human host to take place. They become obviously symptomatic and can be easily separated from others to prevent the infection from spreading.
HIV viruses integrate into the host cell's chromosome and produce asymptomatic infection. They are unable to reliably detected until 6 months after initial infection. For this reason the virus is easily spread unknowingly through the population. Isolation and quarantine measures cannot be used for this virus because they are able to evade detection for an extended period of time.

What are some examples of DNA viruses?

Herpes (HSV-1), Smallpox (variola virus), Hepatitis B (HBV),

Describe just the biosynthesis stage of infection by a plus strand RNA virus that infects animal cells. Be sure to highlight the first step (as separate from other steps) of this biosynthesis.

During biosynthesis of a plus strand RNA virus, the plus strand is used as a template for translation to make rna dependent rna polymerase. RDRP then creates the complementary minus strand by transcription of the plus strand. RDRP then creates the complementary plus strand from the minus strand it had transcribed previously in order to produce mass amounts of plus strands. RDRP then will translate the plus strand in order to produce viral proteins. This entire process is responsible for mass producing new plus strands and capsid proteins that will be later assembled into new virus particles and takes place in the cytoplasm.

What are some examples of plus strand RNA viruses?

Yellow fever virus (YFV), Dengue fever (DENV) , Poliomyelitis (Poliovirus)

Describe just the biosynthesis stage of infection by a minus strand RNA virus that infects animal cells. Be sure to highlight the first step (as separate from other steps) of this biosynthesis.

When a minus strand virus enters the host cell, it cannot be translated to make RDRP. To overcome this, the minus strand virus includes a premade RDRP enzyme to carry out biosynthesis. RDRP will build the complementary plus strand from the template minus strand in transcription. The plus strand will then be translated to produce enzymes such as RDRP and also used as a template to transcribe mass amounts of minus strands. RDRP will then translate some plus strands into capsid proteins. The overall goal of this process is to produce capsid proteins, mass amounts of minus strands and RDRP enzymes for the new generation of virus particles.

What are some examples of minus strand RNA viruses?

Measles Virus, Mumps (paramyxovirus), Rabies Virus

What are the unique events during the biosynthesis stage of retroviruses? Describe these events and any enzymes that are involved.

After entering the host cell and uncoating, the retrovirus is used as a template to construct DNA by reverse transcriptase. The result is a double stranded DNA that will be transported to the nucleus. In the nucleus of the host cell, the viral DNA will be incorporated by recombination into the host cell's chromosome and becomes known as a provirus. As the host cell then divides, the viral DNA that has integrated will also be replicated during normal cell division. At some point, the viral DNA may be transcribed into viral proteins that make up the capsid as well as the strands of new RNA for the assembly of new retroviruses. The retrovirus will assemble and mature and then leave the host cell via budding, taking some of the host cell's membrane with it in order to form its envelope.

What are some examples of retroviruses other than HIV?

Feline Leukemia Virus, Human T-lymphotropic Virus Type 1 (HTLV-1)

Describe how two distinct anti-viral medications work. Use specific examples for two different viruses. [3 points of extra credit if at least one of your pharmaceuticals and diseases is unique.]

Nucleoside Analogs is a class of drugs, specifically Acyclovir is commonly used for herpes. It works by mimicking the structure of the nucleotide guanine. It contains a sugar group, a nitrogenous base but lacks the phosphate of the guanine. This works by disrupting replication of DNA by DNA polymerase. DNA polymerase will mistakenly pick up the drug acyclovir because of its similar structure and use it as a nitrogenous base when synthesizing new bases. This will disrupt the process of replication and subsequently halt viral replication.

Inhibitors of Viral-Cell Fusion is a class of drugs, specifically Fuzeon works by binding to viral proteins on the surface of the virus as to prevent them from attaching to the host cell successfully. Fuzeon is commonly used in combination with other drugs for HIV. Specifically, Fuzeon binds to HIV to prevent it from attaching to CD4 cells of the host it has entered.

Describe two ways that viruses can undergo genetic change.

Viruses can undergo genetic change during viral recombination. In this instance, two seperate viruses can infect the same cell and their DNA can become recombined together during assembly. This leaves each virus with DNA and potentially characteristics of each virus.

Viruses can also undergo genetic change during replication as a result of mutation from errors made by rna polymerase.

Describe three properties of viruses that can evolve.

The attachment ability of the virus can evolve that allows it to infect other cells outside of its normal range.

The ability of the virus to evade immune detection in the host can also evolve. It can change the proteins on its surface, making it unrecognizable to antibodies.

A virus can also evolve differences in its replication process. An enzyme may mutate that allows for the process to be more efficient so that replication can be carried out at a higher rate.

Describe the events that would have needed to take place in the transition from pre-biotic to an earth with living cells

To transition from a pre biotic earth to an earth with living cells, there are several conditions and events that would’ve needed to take place. From a geological standpoint, we can determine that there were several inorganic molecules present such as nitrogen, hydrogen, water, ammonia and carbon dioxide. Given the chaotic climate of the earth, it is likely that lightning and other storm conditions and heat were responsible for acting as a catalyst to reactions between these molecules. The Miller Urey experiment demonstrated this as a possibility, finding that biological molecules could develop within days such as ribonucleotides and some amino acids. Additionally, the presence of clay found in abundance on earth's surface at the time would catalyze this formation further. Given the ribonucleotide formation demonstrated in the miller urey experiment has a negative charge, it would naturally be attracted to the positively charged clay. The lipids found in this clay were capable of encapsulating these RNA like molecules creating vesicles. These cell-like formations are likely the intermediate between prebiotic life and early life on earth. Given the requirements for life are liquid water, a carbon source and temperature between -20C and 120C, it is likely that earth was able to rise from these conditions that were present on pre biotic earth.

Describe the setup of the Miller-Urey experiment. What were their results?

The Miller-Urey experiment was set up to simulate the conditions of prebiotic earth. It was a closed system of glass tubes with 2 different compartments and spickets - the spickets were used to collect samples and check progress/results. The different compartments represented different parts of the environment, beginning with the ‘oceanic’ compartment holding liquid water and other inorganic molecules typically found in the oceans. This compartment was heated to simulate the warm temperatures in prebiotic earth and to encourage plenty of evaporation to allow gasses to rise up through the tube to the atmospheric compartment. Inside the atmospheric compartment were primarily inorganic gasses believed to have been present in pre-biotic earth such as N2 and NH3 The atmospheric compartment was hooked up to electrodes that would be turned on any given # of times to simulate lightning and act as a catalyst to stimulate reactions of gasses. The tube below the atmospheric compartment had a coil of cold water wrapped around it to cool it down and aid in the condensing of the gasses and the products of any reactions that took place. This tube then flowed back into the oceanic compartment and this cycle would continue.

What are the main conclusions of the experiment?

The experiment found that within hours, organic compounds like hydrogen cyanide and formaldehyde were capable of forming from the inorganic molecules found in the system. Within days, it was found that biological molecules were able to form, mainly ribonucleotides, and some amino acids. From these two observations, it was concluded that within the closed system given inorganic molecules, biological molecules and compounds were capable of forming. Because the system was meant to simulate the inorganic molecules likely present on prebiotic earth, it is concluded that it is possible that biological molecules could have risen from the inorganic molecules present on prebiotic earth.

What are the limits to the conclusions?

The Miller Urey experiment has limits to the conclusions that can be made from its results. This is due in part to the fact that it is simply a replication of what may have happened on prebiotic earth. There is no way to replicate the exact events as they took place for life to form. Additionally, the experiment demonstrated the ability to make biological molecules from non-organic sources. The experiment did not carry the principle further than making the molecules that can potentially make life. Life was not grown in this experiment and so it cannot be concluded that life could have formed from these conditions.

What has been observed about the possible aggregation of biological molecules into cell-like structures? Be sure to explain the importance of clay, phospholipids, and RNA.

Possible aggregation of biological molecules into cell like molecules has been observed using clay, RNA, and phospholipids. Clay is a positively charged substance, attracting negatively charged substances like RNA, allowing for the accumulation of RNA.
Additionally, phospholipids have been noted to spontaneously create cell-like structures in water. It is observed that if RNA, clay, and phospholipids are put in the same environment, RNA sometimes accumulates inside the cell-like skeletons of the phospholipids, which could possibly be how some of the first cells came to be.

Why is it possible that an RNA World could have existed? In other words, how can RNA carry out the functions of DNA and protein?

Hypothetically it is possible that an RNA world existed because RNA is made up of ribonucleotides which were present in the results of the Miller-Urey experiment. Additionally RNA can carry out the same functions as DNA because it can store information and self replicate utilizing RNA dependent RNA polymerase. It can also carry out the same functions as proteins by acting as a catalyst, specifically ribozyme which catalyzes metabolism.

How do viruses and ribosomes give supporting evidence for the RNA World hypothesis?

RNA in the form of a ribozyme - most famous ribozyme is the ribosome which carries out protein synthesis - is able to perform similar jobs to that of some
enzymes.
Viruses show us that it is possible to store information in the form of RNA and also that replication is possible via utilization of a ribosome.

Why is that life transitioned from an RNA World into one that also relies on DNA and proteins?

Life may have transitioned from an RNA world to one that relies on DNA and proteins in part because of the chemical makeup of RNA. RNA contains an additional oxygen atom and because of oxygen reactive nature, this makes the compound less stable as compared to DNA. RNA and DNA both contain information required for replication but DNA can secure this information better with its less reactive chemical makeup. Additionally, , RNA has only a few chemically active “functional groups”, which limit it to catalysing just a few types of chemical reaction. Functional groups are like tools – the more kinds you have, the more things you can do. Proteins have many more functional groups than RNA.

What are at least two major effects on the evolution of life on earth that oxygenic photosynthesis likely had?

The transition to oxygenic photosynthesis had drastic changes to the earth that impacted the evolution of life on earth greatly.

One of these major changes was the mass extinction of obligate anaerobic life. When oxygen became plentiful, most organisms present on the earth were not chemically suited with the enzymes to process toxic oxygen and therefore all died out.

Another major change is that once oxygenic photosynthesis began, the O3 levels in the atmosphere rose to be able to form the ozone layer. This shielded earth and its life from the toxic UV rays from the sun. With the threat of UV rays mitigated, life was able to evolve to live outside of the oceans that previously protected it from UV rays.

Describe the process of constructing recombinant DNA. You can assume that the unaltered DNA has already been extracted from cells.

-add restriction enzymes that cut the dna into fragments at specific sequences
-sticky ends form from unpaired single stranded nucleotides
-gel electrophoresis will allow us to separate the DNA by base pair size
-cut the gel where the base pairs
-melt the gel, into tube
-sticky ends will be attracted
-dna ligase will bond the sticky ends

What are the two most common genetic alterations made to food crops? For each, what organism is the source of the transgene and what is the trait encoded by the transgene?

One of the most common genetic alterations made to food crops include herbicide resistance for crops like corn. This is accomplished by extracting DNA from salmonella and incorporating it into corn so that they contain the transgene for resistance to herbicides.

Another common genetic alteration made to food crops is the incorporation of a gene from Bacillus thuringiensis into corn plants. This transgene comes from the bacteria and it makes the corn capable of producing its own pesticide to prevent insects from feeding on before harvesting.

Why is it possible to successfully genetically engineer organisms with genes from unrelated species, such as engineering bacteria with human genes?

It is possible to successfully engineer organisms with genes from unrelated species because of the universal nature of DNA. The genetic code, regardless of species is made up of the same 4 nucleotides with only the unique sequences between species differing. The processes of translation of the DNA and transcription that take place are universal as well, allowing for the same replication and manufacturing process of proteins across all organisms. Additionally, cells in general, cannot distinguish between DNA from an outside source once incorporated into the genome. This is what makes engineering bacteria with human genes possible.

What is one key similarity between traditional breeding and modern genetic engineering? What are two key differences between the two? In your opinion, would you consider modern genetic engineering to be a simple extension of traditional breeding or a radical advance? Explain the reason for your opinion.

The key similarity between traditionally breeding and modern genetic engineering is that they are both working towards the same goal. That being, manipulating the process of replication in order to produce a desired expression of a trait.
One of the key differences between genetic engineering and traditional breeding is that genetic engineering is not limited to biological species the same way breeding is. With breeding, the two organisms that will share genes need to be of the same species for the offspring to at the very least be viable but genetic engineering allows for the combining of genes from organisms that would never be able to naturally mate.
Another key difference between breeding and genetic engineering is the way in which the outcome is left up to chance. With traditionally breeding, the outcome can be determined by use of a punnett square based on the principle of how recessive and dominant alleles are expressed. In contrast, genetic engineering does not rely on this method to determine the "success" of the transfer. Because of the nature of genetic engineering and the preciseness of tools like crispr cas9, the odds of "successful" gene transfer are greatly heightened.

Describe one concern with genetically modified foods that is based on environmental or ecological concerns.

There is concern around planting genetically engineered foods because they can lead to environmental contamination through the wind. Wind is the natural way many of these crops are pollinated and pollen can be potentially carried and pollinate wild relatives that were planted nearby.

An ecological concern regarding GE foods is that the pollen from these plants can end up in unexpected places. This is especially a concern with crops that contain the gene from bacillus thuringiensis because they produce an insecticide that is toxic to common pollinators. If this pollen lands on plants outside of the intended crop, they can have adverse effects on the insects that feed on the contaminated plants.

Describe one concern with genetically modified foods that is based on political or economic concerns.

An economic concern around GE foods would be the patenting of these products effectively is like owning the crop and due to the unpredictable nature of where the pollen may land, this introduces vulnerability to surrounding farmers to legal action.

What is the concept behind somatic gene therapy (prior to CRISPR) involving a retrovirus? What kinds of traits can be treated by this type of somatic gene therapy?

The concept behind somatic gene therapy is to use a retrovirus as amechanism for introducing genetic information into a host. The host is afflicted with a recessive disorder such as cystic fibrosis and has two “faulty” genes. The retrovirus will be altered to carry the dominant “working” gene and not cause illness. Because retroviruses work by incorporating into the host’s DNA, the retrovirus carrying the “working” gene will introduce the dominant working allele to the host’s genome via reverse transcriptase. Because the retrovirus carries the dominant allele and does not ultimately remove any genes, this can only be used on recessive disorders. This type of therapy aims to compensate for the “faulty” allele, not remove and replace it as seen with CRISPR

How can CRISPR/Cas-9 be used as a powerful genetic engineering tool? Describe its mechanism as best as you can.

-crispr works by cas 9 cutting the dna
-crispr is the guide rna that leads the cas 9 where to cut
-crispr makes base pairs with the designated sequence for cutting
-crispr provides the replacement sequence for the genes being removed in cutting

Describe just the biosynthesis stage of infection by DNA viruses that infect animal cells.

...

How is it that early cellular metabolism relied on H­2 gas an energy source? Where is this type of metabolism currently found? What is the name of one microbe that can perform H2 based metabolism (be sure to give full genus and species name)? [Extra credit if no one else chooses the same organism.]

In early cellular metabolism there was very little oxygen gas (o2) and probably not much carbohydrates so the typical metabolism such as glycolysis, fermentation, and photosynthesis was not happening back then but the atmosphere did have inorganic molecules such as hydrogen gas (H2). H2 was an alternative energy source for cellular metabolism because it could be broken down by primitive hydrogenase, an enzyme that breaks H2 into protons and electrons, and then the protons could then form a concentration gradient across a cell membrane building up potential energy. These protons could then cross the membrane via facilitated diffusion utilizing the potential energy and primitive ATPase to create ATP (energy). Today, this simple form of cellular metabolism is found in microbes living in deep-sea hydrothermal vents such as the hydrogenotrophic bacterium Desulfonauticus submarinus.
→ today also found in the guts of termites such as Dehalobacter restrictus

How are Banded Iron Formations evidence for the origins of oxygenic photosynthesis?

The findings of banded iron formations allude to the indirect evidence of the origin of oxygenic photosynthesis a little less than 3 BY ago. This is because most iron in the environment is found in the form of Fe2+, which is soluble in water but when it interacts with O2, it oxidizes into Fe3+, an insoluble form of iron that instead of dissolving in water precipitates. When Fe3+ is formed it settles at the bottom of the water forming reddish bands in the banded iron formation and the darker layers indicate an interruption in this process, most likely from an event removing the presence of O2 in that environment. This cycle continued until about 1.9 BY ago when it is believed that all the Fe2+ was used up and the O2 then began to accumulate in the atmosphere.

Describe how Panspermia offers an alternative hypothesis as to the origins of life on earth. What is the evidence in support of this hypothesis?

Panspermia is an alternative hypothesis to the origins of life on earth and it is the idea that life originated somewhere else in the cosmos and actually crash landed on earth via a meteorite carrying spores and that these spores are what actually seeded the earth. It's a theory that stands on the basis that a billion years is not enough time for the evolution of the first cells and that life had to have come from somewhere else. This theory is supported by evidence of different meteorites that have crashed on earth such as the ALH 84001 meteorite from Mars that landed in Antarctica 11,ooo years ago. Scientists observed lifelike structures on it that looked like fossilized microbes and found Polycyclic aromatic hydrocarbons which are from the decay of organic matter. Additionally, on another meteorite that landed in Australia scientists found amino acids. These discoveries aid in the hypothesis that a meteorite either carried spores or maybe even molecules that landed on earth and seeded at least some of the things in the origin of life on earth.

How are the viruses used for this procedure? (C) What is the difference between in vivo and ex vivo gene therapy? (D) What are two safety concerns with somatic gene therapy?

The difference between in vivo and ex vivo gene therapy is that in vivo gene therapy involves injecting an altered virus directly into the pt and the target organ, for example the liver for hemophilia. For ex vivo therapy, typically used for blood disorders, they will extract live cells in bone marrow from the pt and then add the necessary cells to it in a lab and then inject it back into the pt.


Two safety concerns surrounding somatic gene therapy include how the DNA integrates into the host genome as well as the reaction of the body after DNA integrates. First, the mechanism by which retroviruses integrate the working gene is not precise. The lack of preciseness can lead to the gene being integrated into an important area of the host genome. This can cause unpredictable frameshift mutations within the host genome with varying degrees of consequences. Many cases of patients treated with somatic gene therapy have seen increased rates of cancer from this very gamble that is taken when utilizing somatic gene therapy. Secondly, because exogenous DNA is being incorporated into the host, this can cause severe immune reactions in the host. This has led to some prominent deaths of patients as they died as a result of their strong immune reaction shortly after undergoing this type of gene therapy.

How does synthetic biology take genetic engineering further? In other words, what are the technical goals of some synthetic biology projects? Be sure to describe the general goals as well as two examples.

Choose or create a genome and introduce it into living cells [genral goal]
Synthetic polio
Synthetic mycoplasma
Construct genome of M. genitalium in vitro (2008). Transfer this synthetic genome to a living cell -
Mycoplasma laboratorium (2010).
Biofuels or other industrial products.
Biological weapons.