21 - Manipulating genomes

Question 1

What is the process of producing a DNA profile (genetic fingerprint) ?

Answer 1

1) Extract DNA
2) Digest the sample
3) Separate the DNA fragments
4) Hybridisation
5) Visualisation

Question 2

What is satellite DNA?

Answer 2

short sequences of DNA within introns, telomeres and centromeres, that are repeated many times

Question 3

What are minisatellites?

Answer 3

• also called variable number tandem repeats
• a sequence of 20-50 base pairs that are repeated from 50 to several hundred times
• these occur at more than 1000 locations on the human genome

Question 4

What are microsatellites?

Answer 4

• also called short tandem repeats
• 2-4 bases repeated only 5-15 times

Question 5

What is the location of satellites? How do they vary between individuals?

Answer 5

-Satellites always appear in the same locations on a chromosome
-but the number of repeats varies between individuals​
-The more closely 2 people are related, the more similar their satellites should be

Question 6

Why are introns not used usually?

Answer 6

Coding DNA (exons) is not used because in reality, in most people the coding genome is very similar, so a unique pattern would not be gained.

Question 7

What is DNA profiling used for?

Answer 7

DNA profiles can be used to identify individuals, establish genetic relationships and compare relatedness

Question 8

What is DNA profiling?

Answer 8

Producing an image of the patterns in DNA

Question 9

What is the first step of DNA Profiling?

Answer 9

Extraction of DNA

• initially large samples of DNA was needed, but now only the tiniest of fragments is needed and PCR is used to make large amounts of the sample

Question 10

What are the steps of PCR? Describe them.

Answer 10

1) Denaturation (96 °C): Heat the reaction strongly to separate, or denature, the DNA strands. This provides single-stranded template for the next step.
2)Annealing (55 - 65°C): Cool the reaction so the primers can bind to their complementary sequences on the single-stranded template DNA.
3)Extension (72 °C): Raise the reaction temperatures so Taq polymerase extends the primers, synthesizing new strands of DNA.

This cycle repeats 25 - 35 times in a typical PCR reaction

Question 11

What is Taq polymerase?

Answer 11

PCR requires a DNA polymerase enzyme that makes new strands of DNA. The DNA polymerase typically used in PCR is called Taq polymerase, after the heat-tolerant bacterium from which it was isolated (Thermus aquaticus).

Question 12

Why is Taq polymerase used?

Answer 12

T. aquaticus lives in hot springs and hydrothermal vents. Its DNA polymerase is very heat-stable and is most active around 70°C (a temperature at which a human or E. coli DNA polymerase would be non-functional). This heat-stability makes Taq polymerase ideal for PCR. As we’ll see, high temperature is used repeatedly in PCR to denature the template DNA, or separate its strands.

Question 13

What is a PCR primer?

Answer 13

a short sequence of nucleotides that provides a starting point for DNA synthesis.

PCR primers are short pieces of single-stranded DNA, usually around 20  nucleotides in length. Two primers are used in each PCR reaction, and they are designed so that they flank the target region (region that should be copied). they are given sequences that will make them bind to opposite strands of the template DNA, just at the edges of the region to be copied. The primers bind to the template by complementary base pairing.

When the primers are bound to the template, they can be extended by the polymerase,

Question 14

What is the second step of DNA profiling?

Answer 14

Digest the sample: Cut it into smaller sections using enzymes known as restriction endonucleases.

Question 15

How is the sample in DNA profiling digested?

Answer 15

-Restriction endonucleases are used to cut the DNA into smaller pieces

-They cut the DNA at locations known as restriction/recognition sites which have specific nucleotide sequences (allowing the enzyme to recognise the site)

-The enzymes make 2 cuts, one on each strand, breaking the molecule apart

-A mixture of different restriction endonucleases are used which each target specific restriction sites

-They will choose a combination of enzymes that leave satellite DNA intact, therefore the resulting fragments of DNA contain a mixture of intact satellite sections.​

Question 16

Why do different restriction endonucleases cut at different sites?​

Answer 16

Because the shape of a specific recognition sequence is complementary to the active site of that enzyme. This enables many different satellites to be cut out.​

Question 17

What is the third step of DNA profiling

Answer 17

To produce a pattern that can be analysed, the fragments must be separated from one another

This is done through gel electrophoresis: a technique that utilises that uses the way charged particles move through a gel medium

Question 18

Explain gel electrophoresis

Answer 18

A sheet of agarose gel is produced (roughly 0.5-1cm thick) using agarose powder and a buffer solution (which maintains pH)

The gel will have a row of small wells at one end

The gel is placed into a tank containing more buffer

The digested DNA samples containing satellites are deposited into the wells

A “Ladder” is added to one of the empty wells. This contains DNA fragments of known lengths, and is used as a reference to compare the other fragments to.

On one end of the tank (near the wells) is the negative cathode, at the other end is the positive anode

DNA is negatively charged due to the phosphate groups and so will move through the gel towards the anode when an electric current is flowing

Agarose gel has a 3D mesh-like structure

DNA has to pass through this mesh to get towards the anode

Small DNA fragments pass though the gel faster than larger fragments

This means that when the current is turned off at the end of the process, the smaller fragments will be closer to the anode than the larger fragments

Question 19

What is the fourth step of DNA profiling?

Answer 19

Hybridisation: Radioactive or fluorescent probes are added to the DNA fragments to bind with them.​

Question 20

What is southern blotting?

Answer 20

• the agarose gel is immersed in alkali in order to separate the DNA double strands into single strands (ssDNA).

The single stranded DNA fragments are transferred to nitrocellulose paper of nylon membrane and is covered by absorbent paper.

This draws the alkaline solution containing the DNA through the membrane by capillary action.

The ssDNA is pulled up along with the solution and is caught by the paper/membrane as it can’t pass through it​

UV light or 80C heat is the applied, which fixes the DNA in place on the sheet in the same positions they were in the gel

Question 21

What are DNA probes?

Answer 21

These are radioactive or fluorescent short DNA or RNA sequences that are complimentary to known DNA sequences in the microsatellites

They bind to complimentary strands under certain conditions of pH or temperature

• excess probes have been washed off

Question 22

What is the 5th step of DNA profiling?

Answer 22

Visualisation of evidence: X-ray images are taken to create a DNA profile.

Question 23

Describe the process of gene ‘Sanger’ sequencing

Answer 23

Sanger sequencing uses radioactive (1) modified bases, terminators / ddNTPs (1) to terminate elongation of the DNA strand (1). Use four different reaction mixtures, each one containing a different ddNTP. (1) The primers anneal to the template strand and DNA polymerase can then bind to the dsDNA (1). As the strand is copied by DNA polymerase, the ddNTPs are incorporated randomly (1) so that many different fragment sizes are produced, each terminating with a certain ddNTP (1). Run the four different samples on an electrophoresis gel to separate the different fragments on the basis of size (1). Visualise using radioactive film (1). Read the bands – each band will show a particular fragment ending in a particular ddNTP​

Question 24

What is Sanger sequencing, and what is its primary purpose in molecular biology?

Answer 24

Sanger sequencing is a DNA sequencing method used to determine the nucleotide sequence of a DNA molecule. It is essential for identifying genetic sequences and understanding genetic variation.

Question 25

How does Sanger sequencing work at the molecular level?

Answer 25

Sanger sequencing relies on the incorporation of chain-terminating dideoxynucleotides (ddNTPs) into a growing DNA strand, resulting in fragments of varying lengths that can be separated by size and analyzed.

Question 26

What is the significance of the four chain-terminating dideoxynucleotides (ddNTPs) used in Sanger sequencing?

Answer 26

The four ddNTPs (ddATP, ddTTP, ddCTP, and ddGTP) are used to halt DNA strand synthesis at specific points, enabling the determination of the DNA sequence.

Question 27

How are DNA fragments separated and visualized in Sanger sequencing?

Answer 27

DNA fragments are separated by size using gel electrophoresis, and the separated fragments are visualized by exposing them to a fluorescent dye and detecting the emitted fluorescence.

Question 28

In Sanger sequencing, why is a primer required to initiate DNA synthesis?

Answer 28

A primer is needed to initiate DNA synthesis because DNA polymerase requires a starting point (primer) with a free 3'-OH group to add nucleotides.

Question 29

What is the role of DNA polymerase in Sanger sequencing?

Answer 29

DNA polymerase is used to replicate the DNA template by incorporating regular deoxynucleotides (dNTPs) and chain-terminating ddNTPs into the growing DNA strand.

Question 30

How is the DNA sequence determined during Sanger sequencing?

Answer 30

The DNA sequence is determined by analyzing the order of ddNTPs that terminate the DNA fragments in each of the four separate reactions, corresponding to each base (A, T, C, and G)

Question 31

What are some applications of Sanger sequencing in biology and research?

Answer 31

Sanger sequencing is used for DNA sequencing of specific genes, identifying mutations, studying genetic disorders, and validating PCR products, among other applications.

Question 32

What are some limitations of Sanger sequencing compared to more recent sequencing methods?

Answer 32

Sanger sequencing is relatively slow, labor-intensive, and less cost-effective for large-scale sequencing projects compared to Next-Generation Sequencing (NGS) methods.

Question 33

How do terminator bases work in Sanger sequencing?

Answer 33

These are modified nucleotides that lack the 3' hydroxyl (-OH) group, which is necessary for DNA strand elongation. In Sanger sequencing, each of the four terminator bases (ddATP, ddTTP, ddCTP, and ddGTP) is used in separate reactions, alongside their regular deoxynucleotide counterparts. when a DNA polymerase enzyme encounters a terminator base (ddNTP), it cannot add more nucleotides to the growing DNA strand because the 3' hydroxyl group required for the formation of phosphodiester bonds is absent. As a result, the DNA synthesis process is prematurely terminated at the site where the terminator base is incorporated.

Question 34

What does DNA synthesis in sanger sequencing produce?

Answer 34

This process generates a set of DNA fragments of different lengths, with each fragment ending at the position where a terminator base was incorporated.

Question 35

What is capillary sequencing, and how does it relate to DNA sequencing?

Answer 35

Capillary sequencing is a modern DNA sequencing technique that uses capillary electrophoresis to separate DNA fragments. It is a high-throughput method commonly used for DNA sequencing

Question 36

How is DNA sequencing accomplished in capillary sequencing, and what is the role of capillaries in the process?

Answer 36

In capillary sequencing, DNA fragments are separated in thin capillaries filled with a gel matrix. As the fragments move through the capillary, they are separated by size, enabling the determination of the DNA sequence.

Question 37

What advantages does capillary sequencing offer over traditional Sanger sequencing?

Answer 37

Capillary sequencing is faster, more automated, and provides higher throughput compared to traditional Sanger sequencing. It is well-suited for large-scale DNA sequencing projects.

Question 38

How are DNA fragments labeled for detection in capillary sequencing?

Answer 38

Fluorescent dyes are commonly used to label DNA fragments. Each of the four nucleotide bases is typically labeled with a different fluorescent dye, allowing for their identification during electrophoresis.

Question 39

How is the DNA sequence determined in capillary sequencing, and what data is generated?

Answer 39

The DNA sequence is determined by analyzing the order of the fluorescently labeled peaks corresponding to the four nucleotide bases as they pass through the capillary. This data generates a sequencing trace.

Question 40

Explain capillary sequencing

Answer 40

In capillary Sanger Sequencing, four different terminators are used (A, C, T and G).​ Each is labelled with a different fluorescent dye​. Due to this, only 1 tube needs to be used and all four terminators can be used at once.​ The DNA is put at the end of a long thin capillary tube filled with agarose gel​ A current is passed though the gel causing the DNA fragments move towards the negative electrode​ The smaller fragments move more quickly than the larger ones so the fragments separate in the capillary tube (longest at the beginning, shortest at the end​ Because each terminator base has its own fluorescent colour, lasers can be used to distinguish which bases are present, and in which order​ The sequence can then be read using lasers and light sensors​

Question 41

How is the genome of an organism sequenced?

Answer 41

Only small sections of a genome can be sequenced at once​ 1,000s of BPs at a time​ The Human genome is 3 Billion BPs long​ To produce a full genome sequence these sections need to be patched together to complete the genome​ This is done by identifying overlapping sectio

Question 42

What is a ddNTP?

Answer 42

A dideoxynucleotide triphosphate. A dNTP (free nucleotide with 3 phosphates) missing an oxygen on its 3rd carbon. This makes it unable to form phosphodiester bonds. When it is added by DNA polymerase this terminates DNA synthesis. They are also known as terminator bases and are usually tagged with a radioactive or fluorescent dye.

Question 43

What is Next-generation sequencing?

Answer 43

Any method of DNA sequencing that has replaced the Sanger method is referred to as nextgeneration sequencing (NGS)

Question 44

Why is NGS more desirable than older methods?

Answer 44

NGS methods can be one thousand times faster than older methods of sequencing * The reduction in time required for sequencing means that costs are also greatly reduced o NGS methods cost roughly 0.1% of the cost of chain-termination methods

Question 45

What is nanopore technology?

Answer 45

determines the order of nucleotides in DNA or in RNA by measuring fluctuations in an electric current as the molecule passes through a nanopore.

Question 46

How does nanopore technology work?

Answer 46

- The nanopore is embedded in a membrane that separates two chambers containing electrolyte solutions - voltage is applied, an enzyme steadily ratchets the molecule through the nanopore along -its sequence based is on how much short sequences of individual nucleotides block the flow of ions and tiny changes in electrical current.

Question 47

What is the human genome project?

Answer 47

- an international research program involving over 1000 scientists. It was a publicly funded project, aiming to map and understand all the genes in the human genome -The Human Genome Project determined there are just over 20,000 human protein-coding genes. reflects how complex the regulation of these genes has to be

Question 48

What was the main purpose of the human genome project?

Answer 48

The main purpose of the human genome project was to identify the entire genetic makeup of humans. It would help in identifying genes involved in various genetic diseases.

Question 49

What did the human genome project discover?

Answer 49

The human genome project identified all the genes present in the DNA of humans, the sequence of these genes, and the identification of alleles that might be mutated in certain disease conditions.

Question 50

How many genes are in the human genome?

Answer 50

The human genome project concluded that there are around 20,000 to 25,000 genes present in the entire human genome. The sequence of all these genes has been identified

Question 51

How are DNA strands of different lengths separated during DNA sequencing?

Answer 51

By gel electrophoresis. DNA is negatively charged so moves through the agarose gel towards the anode. Smaller DNA strands move faster than longer ones.

Question 52

What is ddNTP?

Answer 52

A dideoxynucleotide triphosphate. A dNTP (free nucleotide with 3 phosphates) missing an oxygen on its 3rd carbon. This makes it unable to form phosphodiester bonds. When it is added by DNA polymerase this terminates DNA synthesis. They are also known as terminator bases and are usually tagged with a radioactive or fluorescent dye.

Question 53

How can fragments of a genome (≈1,000bp) be used to produce a full?

Answer 53

Computers can be used to identify overlapping regions. These overlapping regions can then be used to identify the location of DNA fragments relative to each other

Question 54

How is capillary sequencing different from traditional Sanger sequencing?

Answer 54

In sanger sequencing radioactive tags are added to terminator bases. This means that tagged DNA strands ending in A,T,G,or C are indistinguishable. Because of this they have to be produced separately and then run in separate wells on a gel. In capillary sequencing 4 different fluorescent tags are used meaning stands ending in a particular base can be distinguished. The reaction can be carried out in one container and separated in the same lane. DNA bases can then be automatically read as they pass a laser and imaging setup.

Question 55

Give four examples of further methods in sequencing?

Answer 55

-Whole genome sequencing -High-throughput sequencing -Pyrosequencing -Nanopore sequencing

Question 56

In nanopore sequencing, what moves the DNA through the nanopore? (what else does it do?)​

Answer 56

A specialised enzyme. (it also unzips the DNA)​

Question 57

In nanopore sequencing, what does the computer detect to determine the sequence of a DNA strand?

Answer 57

A change in the flow of ions through the nanopore & tiny changes in electrical current

Question 58

Name 2 advantages of nanopore sequencing.

Answer 58

Fast, portable, can sequence very long sections of DNA, produces a sequence in real time, Automatically reads the reverse strand.

Question 59

How many protein coding genes are present in the human genome, why was this surprising and what does this tell us about our genome?​

Answer 59

20,000. Surprising as we expected more due to how more simple organisms had. It tells us that gene regulation plays a large role in producing the wide variety of different human proteins.​

Question 60

3 key applications of DNA sequencing

Answer 60

Genome-wide comparisons between individuals and species.​ Predictions of amino acid sequences.​ Development of synthetic biology.​ ​

Question 61

What is bioinformatics?

Answer 61

Developing and using computer software that can analyse, organise, and store biological data.​

Question 62

Uses of bioinformatics?

Answer 62

This can help because i.e. a new allele is sequenced, we can compare against other alleles held in a database, we can then analyse the differences and find out how it will affect the subsequent protein shape.​ The large amount of data on DNA and proteins can be used to make comparisons i.e. think how useful it can be when tracking strains of a pathogen or identifying different species.​

Question 63

What is Computational Biology

Answer 63

Using computers to study biology through theoretical modelling i.e. simulations.

Question 64

When has Computational biology been used

Answer 64

build highly-detailed models of the human brain, ​ map the human genome, ​ assist in modelling biological systems.

Question 65

What is genomics?

Answer 65

combines DNA sequencing and computational biology to analyse the entire structure and function of genomes.​

Question 66

What is genomics used to study?

Answer 66

-genotype-phenotype relationships. ​ - The diversity of species and evolutionary relationships between organisms - Epidemiology – the study of health and disease. -Epidemiology – the study of health and disease.​

Question 67

how is genomics to study genotype-phenotype relationships?

Answer 67

This means we can sequence someone’s DNA, locate their genotype for a certain gene and subsequently predict their phenotype. ​ For example, Marfan syndrome is a mutation of the FBN1 gene. This gene is responsible for the stability of our connective tissue. By sequencing the various mutations, scientists can now predict what health problems an individual with Marfan syndrome will face.​

Question 68

how is genomics to study the diversity of species and evolutionary relationships between organisms?

Answer 68

“DNA Barcoding” a method of species identification where short sections of DNA shared in common are compared to distinguish species. These can be added to a database for easy identification.​ Also, sequencing entire genomes or shared genes (housekeeping genes) and comparing them can reveal to us how long ago there was a common ancestor i.e. the greater the difference between their sequences, the longer ago the ancestor was. ​ This can be used to gain greater understanding of phylogeny​ The average rate of mutation is also known so we can use this to build timelines and estimate how long ago a speciation event occurred​

Question 69

What is DNA Barcoding?

Answer 69

method of species identification where short sections of DNA (that are highly conserved) shared in common are compared to distinguish species. These can be added to a database for easy identification.​ In humans the short section often chosen is a 648 base pair section of mtDNA (its small enough to be sequence quickly but varies enough to be different between species)

Question 70

how is genomics to study Epidemiology – the study of health and disease?

Answer 70

-Certain gene mutations are linked to a greater chance of a certain disease. This information can be provided to doctors and patients to allow them to more accurately measure and manage risk​ E.g. regular mammograms or even choose to have mastectomies. ​ Many of these risk associated genes can only be identified with vast quantities of genomic data and medical records​ -Sequencing pathogenic genomes means we can work out i.e. if we are dealing with a resistant strain of bacteria, the progress and movement of a virus or the origin of an outbreak​. We can also analyse the effectiveness of a vaccine or drug by modelling viral proteins. (or identify possible targets)​. Pathogen genomes are regularly sequenced due to their usefulness and simplicity

Question 71

What is the purpose of identifying genes in people’s genomes that increase the risk of certain diseases if people are unable to change their DNA?

Answer 71

Awareness of risk, can adopt mitigation strategies, doctor can advise strategies to help high risk individuals e.g. more frequent check ups, medication, surgery.

Question 72

What is phylogeny?

Answer 72

The history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms.​

Question 73

What kind of genes are typically used when comparing DNA sequences of distantly related species?​

Answer 73

Highly conserved, Housekeeper genes​

Question 74

give three examples of why the sequence of amino acids predicted is not always what is produced?

Answer 74

RNA-editing RNA-processing Post-translation control

Question 75

How do spliceosomes change the sequence of amino acids?

Answer 75

- Spliceosomes are large structures made from proteins and RNA found in the nucleus. These are responsible for turning pre-mRNA into mature-RNA They can join the same exons in a variety of ways to give rise to different proteins.​ This means a single gene can code for several different versions of functional mRNA, which codes for a different sequence of amino acids and therefore different proteins and phenotypes.​

Question 76

How does RNA-editing change the sequence of amino acids?

Answer 76

- after transcription the nucleotide sequence of the mRNA can be changed - addition deletion or substitution of a nucleotide so a single gene can produce many proteins

Question 77

How does post-translational control change the sequence of amino acids?

Answer 77

- can modify the amino acids and the formation of bonds - folding or shortening of peptide chains - addition of prosthetic chain

Question 78

what is synthetic biology ?

Answer 78

an area of research that seeks to create new biological parts, pathways, and organisms, or to redesign systems that are already found in nature

Question 79

What is genetic engineering?

Answer 79

Manipulation of a genome to achieve a certain outcome (i.e. inserting the gene for human insulin into a prokaryotic plasmid)

Question 80

What is a transgenic organism?

Answer 80

Organisms that have had their DNA altered

Question 81

What is recombinant DNA?

Answer 81

DNA that has been artificially combined from different sources, creating a new sequence that does not exist naturally.

Question 82

What are the three stages of genetic engineering?

Answer 82

1. Isolation of desired gene / DNA fragment.​ 2. Insertion of gene / DNA fragment into a vector.​ 3. Transfer of vector into host cell (often bacteria).​

Question 83

What are the two methods for isolating the desired gene?

Answer 83

1. Use of restriction endonucleases.​ 2. Use of mRNA and reverse transcriptase.

Question 84

What is a restriction endonuclease – what does it do?​

Answer 84

An enzyme that cuts DNA at specific locations.

Question 85

how does restriction endonuclease isolate the desired gene?

Answer 85

- they cut DNA at specific areas - cut can leave blunt or sticky ends

Question 86

What is a blunt end? ( Isolation of desired gene)

Answer 86

- when restriction endonuclease cuts straight through both DNA stands

Question 87

What is a sticky end? ( Isolation of desired gene)

Answer 87

- when restriction endonuclase cuts the DNA at restriction sites that are at different lengths, leaving a single stranded overhang, with exposed bases.

Question 88

Why are endonucleases that produce sticky ends preferable?

Answer 88

They make it easier to insert the gene into the DNA of another organism. (complimentary sticky ends fit together)

Question 89

How is mRNA and reverse transcriptase used to isolate desired gene?

Answer 89

1- first isolate the mRNA containing the gene of interest 2- using a primer and reverse transcriptase, complementary DNA (cDNA) can be synthesised 3- heat the mRNA and cDNA to separate the stands 4- DNA polymerase is added to cDNA and dsDNA is formes (double stranded DNA)

Question 90

What is a vector- give two examples

Answer 90

-A vector is something that can carry the required DNA into a host cell.​ - plasmids- small, circular molecules of DNA, separate from chromosomal DNA, that can replicate independently.​ - bacteriophages-These are viruses that infect bacteria.

Question 91

How do u insert the isolated gene into a vector?

Answer 91

- the plasmid is cut open using the same restriction endonuclease that was used to isolate the DNA fragment.​ -The vector DNA and the isolated gene are mixed together.​The complementary bases pair up between them, and hydrogen bonds are formed.​ -An enzyme called DNA ligase is needed in order to form phosphodiester bonds to fully bond the inserted DNA into the vector. This process is known as ligation.​

Question 92

What is ligation?

Answer 92

process of joining two DNA fragments through the formation of a phosphodiester bond, using the enzyme DNA ligase, resulting in the creation of a single, continuous DNA molecule.

Question 93

What is the plasmid called after the gene has been inserted?

Answer 93

recombinant DNA.​ This is because it now contains DNA from two sources.

Question 94

What are three ways a plasmid can be transferred into the host cell?

Answer 94

- chemical- tha use of Ca2+ - electroporation - bacteriophage

Question 95

What is electroporation?

Answer 95

An electrical current is applied to the bacteria. ​ This electrical pulse makes the membrane more porous and opens temporary tunnels.​ It also sets up an electrochemical gradient The electrically induced pores permit the entry of foreign DNA or molecules into the cells. - it can then fuse with the nuclear DNA

Question 96

transferring the vector using a calcium-rich solutions

Answer 96

- both the plasmids and the bacterial cell membrane are negative - Ca2+ ions bind to the negative phosphate groups on the cell surface and neutralise - plasmids can enter the bacterial cell after they have been heat to make a leaky/pours membrane

Question 97

What is electrofusion?

Answer 97

is a technique that uses electric fields to induce the fusion of cell membranes, allowing the combination of two separate cells into a single hybrid cell/polyploid, containing DNA from both.

Question 98

What is electrofusion in animal cells?

Answer 98

-polyploid cells don't survive long in a body -but electrofusion is used for production of monoclonal antibodies

Question 99

What is a monoclonal antibody?

Answer 99

-produced by combining cell producing an antibody with a tumour cell, so it divides rapidly in culture - they are used to identify pathogens, and treat diseases

Question 100

positive ethical issues of genetic engineering of microorganisms

Answer 100

gives us the ability to treat diseases previously thought untreatable (antibiotics, medicines and enzymes). This would reduce suffering, and lessen the burden of these diseases on i.e. families and the NHS.​

Question 101

why do you think the genetic modification of pathogens is so strictly regulated, and to a certain extent, completely banned?​

Answer 101

- the misuses pf science and genetic engineering for hostile purposes (gene editing, gain-of-function technologies) -biowarfares

Question 102

How are the concerns of biowarfare managed?

Answer 102

- lead to “The Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on their Destruction” i.e. the BWC -It was the first multilateral disarmament treaty banning the production of an entire category of weapons

Question 103

What is Bt (bacillius thuringienisis)

Answer 103

- a bacteria that produces proteins toxic to certain insects - it is used to conrtol pests such as caterpillars

Question 104

Outline the mains pros of GM crops

Answer 104

- increased crop yields (due to disease resistance, herbicide resistance and pest resistance) - less use of pesticides (pest resistant GM crops reduce the need, therefore protecting the environment and helping poor farmers) - extended shelf life (reducing food waste) - nutritional value - wider range of growing conditions

Question 105

Outline the mains cons of GM crops

Answer 105

- pesticide resistant pests (harming non-target animals and causing problems such as superweeds) - biodiversity could be reduced if herbicides are overused - transferred genes could be spread to wild populations

Question 106

How could GM crops assist in improved nutrition and increased yields in less economically developed countries?

Answer 106

-can bolster nutrition in less economically developed countries by incorporating essential vitamins and nutrients directly into the crops, addressing prevalent deficiencies. -GM crops engineered for resistance to pests, diseases, and environmental stresses can enhance yields, ensuring a more reliable and abundant food supply. -The adaptability of GM technology allows for the customization of crops to local conditions, fostering agricultural sustainability in resource-constrained settings.

Question 107

What is golden rice (as a GM crop)?

Answer 107

- produces beta-carotene

Question 108

What are GM pigs?

Answer 108

- swine fever-resistant pigs - scientist inserted a gene from wild African pigs into European pigs to give them immunity

Question 109

What is GM Atlantic salmon?

Answer 109

- Faster growing salmon - received genes from faster-growing chinook salmon (they then produce growth hormones all year round)

Question 110

What is pharming?

Answer 110

- the production of human medicines

Question 111

What is creating animal models in pharming?

Answer 111

- the addition or removal of genes so that animals develop certain diseases, acting as models for the development of new therapies. - e.g. knockout mic have genes deleted so they are more likely to develop cancer

Question 112

What is creating human proteins in pharming?

Answer 112

- the introduction of a human gene coding for a medically required protein - bacteria cannot produce all the complex proteins made by eukaryotes - human gene is introduced into animal egg along with a promoter sequence, so the gene is only expressed in mammary glands - the fertilised transgenic female embryo is returned to the mother. - it is born and grows. its milk contains the desired human protein and is harvested

Question 113

What are the two types of gene therapy in humans?

Answer 113

Somatic Germ line cell

Question 114

How do you replace a faulty recessive allele with a healthy one? (gene therapy)

Answer 114

you can add a dominant allele

Question 115

How do you replace a faulty dominant allele with a healthy one? (gene therapy)

Answer 115

attempt to silence the gene by breaking it up with some DNA in the middle of it

Question 116

What are somatic cells?

Answer 116

normal body cells

Question 117

What is somatic cell gene therapy?

Answer 117

Therefore this type of gene therapy involves altering faulty alleles in these body cells.​ This can be through many ways i.e. adding a copy of a working gene into the nucleus so that it now produces a key protein, or one that synthesises a repressor protein to silence a faulty gene.​

Question 118

Is somatic cell gene therapy a cure?

Answer 118

it isn't - the healthy allele will be passed on every time a cell divides but somatic cells have limited life, so repeated treatments are needed - it can still be passed on to offspring

Question 119

What are germ line cells?

Answer 119

Gametes or an embryo immediately following fertilisation

Question 120

What is Germ line cell gene therapy?

Answer 120

This involves editing a defective allele in a gamete so offspring do not suffer from the disease i.e. they are born healthy.​ This is currently illegal for human embryos, but has been done with animal embryos

Question 121

What are the cons of human gene therapy?

Answer 121

Potential overexpression of genes i.e. too much of missing protein expressed.​ Decision being made on what genes are “normal” and what cause a disability. Could disability become less acceptable? Could extraordinary people not be born?​ Expensive – is money better spent on other treatments? i.e. Somatic therapy is often short-lived, and patient can end up requiring multiple treatments.​

Question 122

What are the pros of human gene therapy?

Answer 122

Prolong life / allow for better quality of life for people with various disorders;​ Germ line could ensure carriers of genetic disorders can have a baby without risk of inheritance. Could also decrease number of people suffering from genetic disease.​