Genetic Technology
178 questions· page 1 of 18
To produce a human protein for treatment of a disease, recombinant DNA technology needs a gene coding for the particular human protein.
Outline the different ways that can be used to obtain a gene that codes for a human protein.
Diabetes mellitus is a disease in which the blood glucose concentration cannot be controlled. Many people with diabetes mellitus use recombinant human insulin to help control their blood glucose concentration.
Before recombinant human insulin became available, animals were the main source of insulin.
Explain the advantages of using recombinant human insulin to treat diabetes.
Explain why the DNA involved in the production of recombinant human insulin is termed recombinant DNA.
Recombinant human insulin analogues are insulin proteins that have slightly altered amino acid sequences compared with recombinant human insulin. These analogues can be more effective than human insulin.
Synthetic genes coding for insulin analogues have been developed. The bacterium Escherichia coli can be used as a host for a synthetic gene for the large-scale manufacture of an analogue.
When scientists have determined the changes that are needed to produce an insulin analogue, they can obtain a synthetic gene coding for the analogue by making changes to a length of DNA using genetic engineering.
Suggest how scientists genetically engineer a synthetic gene coding for the insulin analogue and explain how the changes they make allow the correct analogue to be produced.
Recombinant human insulin is a protein that is made using recombinant DNA technology.
Bacteria can be used as host cells to express the recombinant protein.
For the human insulin gene to be successfully expressed in bacteria, one method chosen to obtain the gene is to extract mRNA from -cells in the pancreas.
The gene coding for insulin is not expressed in the bacterial host when it has been obtained by cutting it out of genomic DNA.
Suggest and explain how the structural difference of cDNA and genomic DNA leads to only cDNA being expressed successfully.
Explain why a promoter, as well as the gene, may have to be transferred into the plasmid.
The unicellular fungus Saccharomyces cerevisiae is a species of yeast that has been used to produce human insulin. S. cerevisiae cells are able to take up recombinant plasmids.
Suggest advantages of using yeast compared to using bacteria for human insulin production.
Explain how the modification made to produce LibertyLink® soybean may help to solve the global demand for food.
Name the type of enzyme that could be used to cut out the pat gene from S. viridochromogenes.
Name the enzyme that could be used to join the pat gene to a plasmid by forming phosphodiester bonds.
Suggest reasons why LibertyLink® soybean is used in food products in 21 countries but only grown in 6 countries.
Genomic DNA and primers are added to the PCR machine.
Name two other substances that are added to the PCR machine, and explain why each substance is added.
In the genetic test for MLD, PCR and gel electrophoresis are carried out before DNA sequencing.
Suggest and explain reasons why PCR and gel electrophoresis are carried out before DNA sequencing.
Calculate the number of copies of DNA that are obtained if PCR is run for 35 cycles.
Assume that there is only 1 copy of DNA at the start of PCR.
Give your answer in standard form to two significant figures.
number of copies = ______
MLD is a rare autosomal recessive disease. It is estimated that there is one case of MLD in every 40000 births worldwide. Children with MLD have a reduced life expectancy.
- MLD is a degenerative disease that causes severe disability.
- Before 2022, there was no known cure for MLD and the only treatment for symptoms was to provide pain relief.
A new gene therapy treatment known as Libmeldy® became available in a number of countries in 2022. The treatment must start before symptoms are present. Although the treatment may provide a cure for MLD, a single dose is extremely expensive.
Blood samples from newborn babies are screened for a number of rare genetic diseases (neonatal screening) in most countries of the world, but none include screening for MLD.
Discuss the social and ethical considerations of including screening for MLD when carrying out neonatal screening in a country where gene therapy for MLD is available.
Explain how the modification made to produce LibertyLink® soybean may help to solve the global demand for food.
Name the type of enzyme that could be used to cut out the pat gene from S. viridochromogenes.
Name the enzyme that could be used to join the pat gene to a plasmid by forming phosphodiester bonds.
Suggest reasons why LibertyLink® soybean is used in food products in 21 countries but only grown in 6 countries.
Genetic engineering is a modern method for producing crop plants with improved characteristics.
One example of a crop plant with improved characteristics is soybean, Glycine max, which has been genetically modified to make it resistant to a herbicide. This genetically modified soybean is called GM soybean.
To create GM soybean, a bacterial gene and a section of regulatory DNA were introduced into soybean cells.
Outline the roles of enzymes and a section of regulatory DNA in the creation of genetically modified organisms such as GM soybean.
In 2018, an area of 123.5 million hectares was used to grow soybean crops worldwide.
GM soybean was grown in 73% of this area.
In 2018, soybeans accounted for 50% of the total GM crop area worldwide.
Calculate the total area used to grow GM crops worldwide in 2018.
Show your working.
______
Complete the following paragraphs using the most appropriate word or words.
The theory of evolution describes a process that can lead to the formation of new species from pre-existing species over ______ .
DNA sequence data of different species can be compared to show evolutionary relationships. Two species that have a more recent common ancestor share more ______ in the DNA nucleotide sequences of their genomes than two species that are more distantly related.
Mitochondrial DNA can also be used in the study of evolutionary relationships. Mitochondrial DNA is inherited only from the female gamete, and its nucleotide sequence is unaffected by ______ during the production of gametes.
DNA sequence data can be stored in large biological ______ , allowing faster comparison of the nucleotide sequences of genomes using computer software. DNA sequence data can also be used to predict the ______ sequences of proteins produced by a species.
A ______ can be used to detect many different mRNA molecules at the same time in studies that compare gene expression between different species.
State one reason why a doctor would recommend that a person has genetic testing for a mutation in the gene BRCA1 and explain why this mutation would put the person at a greater risk of breast cancer.
DNA sequencing is one method used to test for mutations in BRCA1. Before DNA sequencing occurs, the DNA sample goes through the polymerase chain reaction (PCR).
Suggest why PCR is used for testing for mutations in BRCA1.
Genetic screening shows that in the UK:
- 1 in 400 females have a mutated allele of BRCA1
- 70% of females with a mutated allele of BRCA1 will develop breast cancer by the time they are 80 years old.
In 2022, the population of females in the UK was .
Calculate the number of females in the UK population in 2022 who it is estimated will develop breast cancer by the age of 80 years old. Give your answer in standard form.
Show your working.
number of females = ______
One advantage of genetic screening is to determine which drugs should be selected to treat cancer.
A study was carried out on women with breast cancer who had been treated with a DNA-damaging drug that kills tumour cells.
The women had all been tested for BRCA1 mutations. One group had a BRCA1 mutation and the other group did not have a BRCA1 mutation.
The researchers used data to assess the probability of survival for the women in each group of the study after treatment with the drug.
Fig. 5.1 shows the probability of survival for a time period of up to 180 months.
The researchers suggested the hypothesis that the DNA-damaging drug is more effective in women with a BRCA1 mutation.
Discuss whether the results in Fig. 5.1 support the hypothesis suggested by the researchers.
Genetic engineering uses specific enzymes and commonly involves the use of plasmids for the transfer of genes into an organism.
Four enzymes that are used in genetic engineering techniques involving plasmids are:
• restriction endonuclease
• DNA ligase
• DNA polymerase
• reverse transcriptase.
Outline the role of these enzymes in genetic engineering involving plasmids.
restriction endonuclease ______
DNA ligase ______
DNA polymerase ______
reverse transcriptase ______
Explain why a promoter, as well as the desired gene, is often transferred into an organism.
The production of insulin by genetic engineering involves the use of plasmids and the bacterium Escherichia coli.
Multiple copies of a gene that codes for an insulin polypeptide are mixed with cut plasmids.
During the process, only some of the plasmids that are taken up by host bacteria will lead to the expression of insulin polypeptides.
Fig. 4.1 shows:
• a cut plasmid and the gene coding for the insulin polypeptide
• three different plasmids that have been formed as part of the genetic engineering process.
Fig. 4.1
Comment on whether a bacterium will produce the insulin polypeptide if it has either plasmid X or plasmid Y or plasmid Z and explain the reason for your choice.
plasmid X ______
plasmid Y ______
plasmid Z ______
Sometimes the gene for genetic engineering cannot be extracted from the donor organism. Instead, the gene is synthesised using one of two different methods.
Outline the two methods for synthesising a gene for use in genetic engineering.
DNA ligase and DNA polymerase are two enzymes that are used in genetic engineering.
Complete Table 8.1 to show the roles of DNA ligase and DNA polymerase in genetic engineering.
Use a tick (✓) if the enzyme has the role or a cross (✗) if the enzyme does not have the role.
Table 8.1
| role in genetic engineering | DNA ligase | DNA polymerase |
|---|---|---|
| joins two sections of sugar phosphate backbone in DNA | ||
| adds a gene to a plasmid | ||
| adds free activated DNA nucleotides to a polynucleotide |
The polymerase chain reaction (PCR) is used to make many copies of a gene.
Three temperatures are used in a PCR cycle.
State the three temperatures that are used, and outline what happens at each temperature during a PCR cycle.