Genetic Modification & Biotechnology (DP IB Biology: SL)

State two features that allow nucleic acids or proteins to be separated by gel electrophoresis.

During gel electrophoresis of a sample of DNA fragments,

State which class of enzymes can be used to cleave DNA into fragments prior to gel electrophoresis.

Restriction enzymes and gel electrophoresis can be used in genetic screening, to identify genes associated with a disease. The mutation of the Beta-globin gene which gives rise to sickle-cell anaemia removes a recognition site of the restriction enzyme DdeI as shown in the diagram below. The lengths of some fragments are shown in base pairs (bp).

Explain what is meant by the term, 'clones'.

The diagram below outlines the process of somatic cell nuclear transfer that was used to create Dolly the sheep. Describe each of the different steps that lead up to implantation.

The graph below shows the survival rates for different cloned animals.

Describe what a genetically modified “transgenic” organism is. 

A bacterial plasmid used for recombinant DNA technology is represented in the diagram below. The amp^R gene encodes for antibiotic resistance.

Explain the usefulness of the amp^R and promoter elements in recombinant DNA technology.

Before the discovery of recombinant DNA technology, diabetics had to be treated with animal insulin obtained directly from animal pancreatic tissue which led to many complications and premature deaths. 

Outline the key steps involved in the commercial production of human recombinant insulin.

The table below shows historic annual mortality from different public health diseases.

Genetic modification has assisted in the fight against four major human diseases. Calculate the disease which showed the largest percentage drop in global mortality in the period 2010 - 2017.

Vitamin A deficiency is prevalent in many developing countries as a result of poor nutrition and is a common source of blindness. ‘Golden Rice’ is a variety of genetically modified rice developed to produce beta-carotene (pro-vitamin A). Golden rice was created by introducing rice with the following beta-carotene biosynthesis genes:

• psy (phytoene synthase) from wild daffodil (Narcissus pseudonarcissus)
• crt1 (phytoene desaturase) from a soil bacterium (Erwinia uredovora)

The pathway for beta-carotene biosynthesis is shown below.

The table below shows the total amount of beta-carotene produced when different psy genes were inserted into ‘Golden Rice’ 

Originally, ‘Golden rice’ did not accumulate high levels of beta-carotene. Identify, with a reason, how it was improved.

Discuss the risks and benefits associated with GM crops.

One mark is available for clarity of communication throughout this question.

Archaeologists in Pompeii recently discovered the remains of seven human skeletons within a house that was buried under volcanic ash when Mount Vesuvius erupted during ancient Roman times in 79 AD. Researchers were interested to know if the skeletons were from related individuals, they isolated DNA from the skeletons and used it in the Polymerase Chain Reaction (PCR).

PCR utilises multiple cycles of three simple steps, describe these steps and suggest why the researchers used PCR in their investigation.

DNA profiling was carried out on the PCR products to identify if the skeletons came from related individuals. The results are seen in the image below.

It was determined that the three children were siblings and shared the same biological parents. Their mother is Adult B.

Outline the method by which DNA profiling is undertaken and describe why it is a useful technique.

Human blood carries several proteins which are required in the mechanism of blood clotting. One of these proteins, factor VIII, is lacking in individuals with haemophilia.

A team of scientists has genetically engineered goats by introducing a gene allowing them to produce factor VIII in their milk. This milk can then be purified and the proteins can be used to treat haemophiliac patients. 

Describe two methods by which the scientists could obtain the human gene coding for the factor VIII protein.

Before carrying out PCR on the isolated gene sequence, the scientists modified the gene in two ways:

1. They attached a jellyfish gene which codes for a fluorescent protein to the start of the gene sequence.
2. They added a promotor region in front of the jellyfish gene. 

After these modifications, the DNA sequence will be inserted into the nucleus of some body cells of a goat.

Suggest the purpose of attaching the jellyfish gene.

The promotor region provides a base sequence compatible with the active site of the enzyme RNA polymerase.

Suggest why the addition of the promotor region is required in the production of factor VIII.

One round of PCR takes approximately 75 seconds.

Calculate how many copies of DNA would be produced after a single fragment of DNA has been in the thermal cycler for 1.5 hours. Give your answer in standard form.

The diagram below shows the processes involved in the amplification of a sample of viral RNA.

Compare and contrast the process in the image with the process used in the amplification of a fragment of DNA.

The addition of RNAase enzyme occurs between stages 3 and 4 shown in the diagram from part a).

Suggest why this is a necessary part of the process.

Seven skeletons were discovered in a house in Pompeii, three of which were children. It is believed they were inhabitants and workers within the house when Mount Vesuvius erupted in 79 AD.

Researchers were able to isolate very small amounts of DNA from these skeletons. The DNA obtained was used in the polymerase chain reaction (PCR). Genetic fingerprinting was then carried out on this DNA to identify the skeletons.

The image below shows some of the results of the genetic fingerprinting of the three children and four adults.

Explain why the researchers used PCR in their investigation.

It was determined that the three children were siblings and shared the same biological parents. Their mother is Adult B.

Identify, with a reason, which of the other adults was the children’s father.

Embryo splitting is a process which can be used to produce larger numbers of high quality cattle for farmers. The process can be seen below.

An embryo with more than 8 cells cannot be used in embryo cloning, suggest why.

Clones produced in the process in part a) may show different phenotypes to each other.

Explain why.

Describe three natural cloning methods used by plants and animals.

An investigation was carried out to show the affect of different rooting powders on the growth of roots in cuttings taken from bean plants.

The results from the investigation are shown in the table.

SE refers to the standard error of the data, which is the spread of data around the calculated mean value.

Suggest the conclusions that can be drawn from these results.

A company selling rooting powder 1 to gardeners made the following claim:

With this rooting powder, your plant cuttings will grow more roots of a greater length than other rooting powders.

Evaluate the validity of this claim.

Outline a method that could have been used to determine how rooting powders affect the growth of roots in bean plants.

One mark is available for clarity of communication throughout this question.

During PCR DNA is heated to 94 °C and DNA primers, nucleotides and thermostable enzymes are added to the mixture.

Explain the purpose of these steps.

Scientists have proposed a method to genetically engineer mosquitos as a method of controlling disease spread by the insects.

Analyse the ethics surrounding the use of genetically engineered mosquitos as a public health tool.

Discuss the use of cloning methods to produce genetically identical copies of organisms in agriculture.