Gene Technologies (A Level only) (AQA A Level Biology): Flashcards
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Define the term recombinant DNA (rDNA)
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Define the term recombinant DNA (rDNA)
Recombinant DNA is DNA that has been altered by combining lengths of nucleotides from different sources, typically from different species.
Define the term transgenic organism
A transgenic organism is one that contains nucleotide sequences from a different species.
Define the term genetically modified organism (GMO)
A genetically modified organism is any organism that has had genetic material introduced into it.
Why can a gene transferred from one species be expressed in the cells of another species?
The genetic code is universal, so the same codons code for the same amino acids in all organisms.
The mechanisms of transcription and translation are also universal, so the transferred DNA can be translated within the cells of the genetically modified organism.
True or False?
The same codons code for the same amino acids in all living things.
True.
The genetic code is universal, which means genetic information is transferable between species.
State the five steps taken to genetically engineer an organism.
Identification of the DNA fragment or gene.
Isolation of the desired DNA fragment.
Multiplication of the DNA fragment (using the polymerase chain reaction).
Transfer into the organism using a vector.
Identification of the cells with the new DNA fragment (using a marker), which is then cloned.
Name three types of vector that can be used to deliver DNA fragments into a cell.
Plasmids
Viruses
Liposomes
Name the three enzymes a genetic engineer needs to modify an organism.
Restriction endonucleases
Ligase
Reverse transcriptase
In genetic engineering, what is a marker?
A marker is a gene that codes for an identifiable substance that can be tracked, for example GFP (green fluorescent protein), which fluoresces under UV light.
Recombinant DNA technology involves the transfer of fragments of DNA from one organism into another; because the genetic code is , the transferred gene can be expressed.
Recombinant DNA technology involves the transfer of fragments of DNA from one organism into another; because the genetic code is universal, the transferred gene can be expressed.
An organism that contains nucleotide sequences from a different species is described as , and any organism with introduced genetic material is a genetically modified organism.
An organism that contains nucleotide sequences from a different species is described as transgenic, and any organism with introduced genetic material is a genetically modified organism.
State the three methods used to produce a fragment of DNA containing a desired gene.
Extracting the gene from donor DNA using restriction endonucleases.
Using reverse transcriptase to synthesise complementary DNA (cDNA) from mRNA.
Synthesising the gene artificially using a "gene machine".
What are restriction endonucleases?
Restriction endonucleases are enzymes found in bacteria that cut DNA at specific base sequences (restriction sites) within the molecule.
What are sticky ends and why are they useful?
Sticky ends are produced when a restriction endonuclease cuts the sugar-phosphate backbone unevenly, leaving one strand longer than the other.
They are useful because they can easily form hydrogen bonds with complementary base sequences on other DNA cut by the same restriction enzyme, making it easier to insert the desired gene.
How are blunt ends produced by a restriction endonuclease?
Blunt ends are produced when the restriction endonuclease cuts the sugar-phosphate backbone straight across, so both strands are the same length.
Why do many different restriction endonucleases exist?
Each restriction endonuclease binds to a specific restriction site (a specific sequence of bases) on DNA.
For example, HindIII always binds to the base sequence AAGCTT.
Describe how reverse transcriptase is used to isolate a desired gene.
The mRNA for the gene is isolated and used as a template.
Reverse transcriptase and nucleotides are used to make a single strand of complementary DNA (cDNA).
DNA polymerase then converts the single-stranded cDNA into a double-stranded DNA molecule.
Why is using cDNA (from mRNA) an advantageous way to isolate a gene?
The gene is easier to find, because specialised cells make very specific types of mRNA (e.g. β-cells of the pancreas produce many insulin mRNAs).
The mRNA, and therefore the cDNA, does not contain introns.
How is a gene synthesised artificially using a "gene machine"?
Using knowledge of the genetic code, computers generate the nucleotide sequence required.
Short fragments of DNA are produced, then joined to make longer sequences of nucleotides, which are inserted into vectors.
True or False?
Reverse transcriptase enzymes are sourced from retroviruses.
True.
Reverse transcriptase enzymes are sourced from retroviruses and catalyse the reaction that reverses transcription.
Reverse transcriptase uses mRNA as a template to make DNA, which DNA polymerase then converts into a double-stranded molecule.
Reverse transcriptase uses mRNA as a template to make complementary DNA, which DNA polymerase then converts into a double-stranded molecule.
A restriction endonuclease that cuts the sugar-phosphate backbone unevenly produces ends, in which one strand is longer than the other.
A restriction endonuclease that cuts the sugar-phosphate backbone unevenly produces sticky ends, in which one strand is longer than the other.
What is gel electrophoresis?
Gel electrophoresis is a technique that uses an electric current to separate DNA molecules according to their size/mass and their net charge.
During electrophoresis, why do DNA fragments migrate towards the positive electrode?
DNA is negatively charged due to its phosphate groups, so in an electric field the fragments move towards the positive electrode.
During electrophoresis, do shorter or longer DNA fragments travel further through the gel?
Shorter fragments travel faster and farther through the gel.
Longer fragments move more slowly, because the tiny pores in the gel slow larger molecules down.
What are restriction fragments?
Restriction fragments are the pieces of DNA of different lengths produced when a DNA sample is digested (hydrolysed) by restriction enzymes.
Outline the steps to separate restriction fragments using gel electrophoresis.
Digest the DNA sample with a restriction enzyme to produce restriction fragments.
Load the fragment mixture into wells cut near the negative electrode.
Run the gel by applying an electric current so fragments migrate towards the positive electrode.
Separate the fragments by size, as shorter fragments travel further than longer ones.
DNA is colourless, so how can the bands of restriction fragments be made visible after electrophoresis?
By using a stain to produce coloured bands.
By treating the DNA with a radioactive marker.
By adding fluorescent probes that bind to the DNA.
How can an unknown restriction enzyme be identified using gel electrophoresis?
Because restriction enzymes are highly specific, the same enzyme always produces the same number and sizes of restriction fragments from the same DNA sample.
The unknown enzyme is identified by comparing its bands with those produced by a known restriction enzyme; matching bands indicate the same enzyme.
True or False?
During gel electrophoresis, larger DNA fragments move faster than smaller ones.
False.
Smaller fragments move faster through the tiny pores in the gel, while larger fragments move more slowly.
On what two properties does gel electrophoresis separate DNA molecules?
Their size/mass.
Their net (overall) charge.
In gel electrophoresis, DNA fragments are negatively charged and so migrate towards the electrode.
In gel electrophoresis, DNA fragments are negatively charged and so migrate towards the positive electrode.
The wells into which the DNA sample is loaded are cut at the end of the gel nearest the electrode.
The wells into which the DNA sample is loaded are cut at the end of the gel nearest the negative electrode.
What is the polymerase chain reaction (PCR)?
The polymerase chain reaction is the in vitro method of DNA amplification, used to produce large quantities of specific DNA fragments from very small quantities.
State the three stages of one PCR cycle and their temperatures.
Denaturation at 95°C.
Annealing at 50–60°C.
Elongation / extension at 72°C.
What happens during the denaturation stage of PCR?
The double-stranded DNA is heated to 95°C.
This breaks the hydrogen bonds holding the two DNA strands together, separating them.
What happens during the annealing stage of PCR?
The temperature is decreased to between 50–60°C.
This allows the primers (forward and reverse) to anneal to the ends of the single strands of DNA.
What happens during the elongation / extension stage of PCR?
The temperature is increased to 72°C, the optimum for Taq polymerase.
Taq polymerase builds the complementary strands of DNA, producing new identical double-stranded DNA molecules.
Why is Taq polymerase used in PCR?
Taq polymerase does not denature at the high temperatures involved in PCR.
Its optimum temperature is high enough to prevent annealing of DNA strands that have not yet been copied.
What are primers in PCR?
Primers are short sequences of single-stranded DNA with base sequences complementary to the 3' end of the DNA being copied.
They identify to DNA polymerase where to begin building the new strands.
List the components required for a PCR reaction.
Target DNA (or RNA) to be amplified.
Primers (forward and reverse).
DNA polymerase (usually Taq polymerase).
Free nucleotides.
Buffer solution to provide the optimum pH.
True or False?
PCR is an in vivo method of amplifying DNA.
False.
PCR is the in vitro method of DNA amplification; in vivo cloning is carried out using bacteria.
In each cycle of PCR the amount of DNA is roughly , so after about 20 cycles a million DNA molecules are produced.
In each cycle of PCR the amount of DNA is roughly doubled, so after about 20 cycles a million DNA molecules are produced.
During denaturation the DNA is heated to 95°C, which breaks the bonds holding the two strands together.
During denaturation the DNA is heated to 95°C, which breaks the hydrogen bonds holding the two strands together.
What are transformed host cells?
Transformed host cells are host cells (usually bacteria) that have taken up the modified plasmids containing the desired gene.
What is the difference between in vivo and in vitro methods of amplifying DNA?
In vitro amplification is carried out by the polymerase chain reaction (PCR).
In vivo gene cloning is carried out inside living cells, usually using bacteria as host cells.
Which enzymes are used to insert a DNA fragment into a vector during in vivo gene cloning?
Restriction endonucleases and ligase enzymes are used to insert the DNA fragment into the vector.
Why are bacteria the most common host cells for in vivo gene cloning?
Bacteria increase in numbers rapidly.
They are relatively easy to culture.
What is the purpose of marker genes in in vivo gene cloning?
Only a small fraction of bacteria take up the plasmid containing the desired gene.
Marker genes allow the successfully transformed bacteria to be identified, so they can be selected and cultured.
Outline the steps of in vivo gene cloning using bacteria.
A DNA fragment is isolated (by one of three methods).
The DNA fragment is inserted into a vector (e.g. a plasmid) using restriction endonucleases and ligase.
The vector is transported into a bacterial host cell, forming a transformed host cell.
The bacteria multiply rapidly under optimum conditions.
Marker genes are used to identify the successfully transformed bacteria.
The transformed bacteria are cultured, cloning the desired gene each time they divide.
Which regions are added to a DNA fragment before insertion into a vector, and why?
Promoter and terminator regions are added to the DNA fragment.
These ensure the fragment is replicated (transcribed) correctly.
What is a marker gene?
A marker gene codes for an identifiable substance that can be tracked, for example GFP (green fluorescent protein), which fluoresces under UV light.
True or False?
Every time a transformed bacterium divides, the desired gene is cloned.
True.
Once the transformed bacteria are cultured, the desired gene is cloned every time a bacterium divides.
Bacterial cells that have taken up the modified plasmid are described as host cells.
Bacterial cells that have taken up the modified plasmid are described as transformed host cells.
The most commonly used vectors for inserting a DNA fragment into a bacterial host cell are .
The most commonly used vectors for inserting a DNA fragment into a bacterial host cell are plasmids.
What is a recombinant protein (RP)?
A recombinant protein is a protein produced from recombinant DNA; it is a manipulated form of the original protein.
Why are most recombinant human proteins produced using eukaryotic cells rather than prokaryotic cells?
Eukaryotic cells (e.g. yeast or animal cells) carry out the post-translational modification required to produce a suitable human protein.
This is because they possess a Golgi apparatus and/or the necessary enzymes.
State some advantages of using genetically engineered organisms to produce recombinant human proteins.
More cost-effective to produce large volumes, with an essentially unlimited, reliable supply.
Faster to produce many proteins.
The proteins can be identical to human proteins or given beneficial modifications.
Fewer moral, ethical or religious concerns than using proteins extracted from cows or pigs.
Give advantages of using recombinant insulin over animal-extracted insulin.
It is identical to human insulin (unless deliberately modified to act faster or slower).
There is a reliable supply to meet demand.
Fewer ethical, moral or religious concerns, as it is not extracted from cows or pigs.
Fewer rejection problems, side effects or allergic reactions.
What is gene therapy?
Gene therapy involves using various mechanisms to alter a person's genetic material in order to treat or cure diseases, for example by replacing, inactivating or inserting a gene.
What is the difference between ex vivo and in vivo somatic gene therapy?
In ex vivo therapy, the new gene is inserted (via a virus vector) into cells outside the body, which are then returned to the patient.
In in vivo therapy, the new gene is inserted (via a vector) into cells inside the body.
Why are changes made during somatic gene therapy not inherited by future generations?
Somatic gene therapy targets specific body (somatic) cells, not the gametes.
As the germ cells are not altered, the changes cannot be passed on to offspring.
True or False?
Germline gene therapy is legal in humans.
False.
Germline gene therapy is illegal in humans, because changes made to germ cells are potentially permanent and could be inherited by future generations.
State the benefits of genetic engineering over traditional selective breeding for improving crops or livestock.
Organisms with the desired characteristics are produced more quickly.
All organisms will contain the desired characteristic (no chance of a recessive allele arising).
The desired characteristic can come from a different species or kingdom.
Give ways in which crop plants have been genetically modified in agriculture.
Resistant to herbicides – increases yield.
Resistant to pests – increases yield.
Enriched in vitamins – increases nutritional value.
An organism that contains introduced nucleotides from a different species is described as , whereas any organism with introduced genetic material is a genetically modified organism.
An organism that contains introduced nucleotides from a different species is described as transgenic, whereas any organism with introduced genetic material is a genetically modified organism.
Cotton has been genetically modified with a gene for the toxin, taken from the bacterium Bacillus thuringiensis, so that it produces its own insecticide.
Cotton has been genetically modified with a gene for the Bt toxin, taken from the bacterium Bacillus thuringiensis, so that it produces its own insecticide.
What is a DNA probe?
A DNA probe is a short length of single-stranded DNA with a known base sequence that is complementary to the base sequence of a known allele.
What is DNA hybridisation?
DNA hybridisation is the process in which two complementary single-stranded DNA molecules combine through base pairing to form a single double-stranded DNA molecule.
What type of label is usually attached to a DNA probe, and why?
A DNA probe is usually attached to a radioactive or fluorescent label.
The label indicates the position of the probe when it binds to a complementary sequence.
How is the position of a bound DNA probe detected for fluorescent and radioactive labels?
For fluorescent labels, UV light is used to detect their position.
For radioactive labels, autoradiography is used to detect their position.
True or False?
A DNA probe used to detect a harmful allele must be complementary to that harmful allele.
True.
The probe must have a base sequence complementary to the harmful allele and must not be complementary to any normal alleles.
On a nylon membrane, why must the DNA fragments be made single-stranded before adding DNA probes?
The fragments are made single-stranded by breaking the hydrogen bonds between complementary base pairs.
This allows the labelled probes to anneal to any complementary DNA fragments present.
Outline how DNA probes are used to locate a specific harmful allele in a patient's DNA.
A cell sample is taken and the DNA is extracted and purified.
The DNA is amplified using PCR, then digested with restriction endonucleases.
The fragments are separated by gel electrophoresis and transferred to a nylon membrane, where they are made single-stranded.
Labelled DNA probes are added and anneal to any complementary (harmful) allele present.
Excess probes are washed off, and the membrane is processed to reveal the position of any bound probes.
In DNA probe testing, what does it mean if a label shows up on a restriction fragment?
If a label shows up, the DNA in that position must be from the harmful allele.
If no labels show up, the test DNA does not contain the harmful allele.
Give two uses of DNA hybridisation with DNA probes.
Medical diagnostic tests.
Genetic screening – to indicate whether specific harmful alleles are present in a DNA sample.
A DNA probe is a short length of DNA with a known base sequence complementary to a specific allele.
A DNA probe is a short length of single-stranded DNA with a known base sequence complementary to a specific allele.
In DNA hybridisation, two complementary single-stranded DNA molecules combine through pairing to form a double-stranded molecule.
In DNA hybridisation, two complementary single-stranded DNA molecules combine through base pairing to form a double-stranded molecule.
Define the term genetic screening.
Genetic screening is the testing of an embryo, fetus or adult to analyse the DNA.
It can help identify individuals who are carrying an allele at a gene locus for a particular disorder.
State two ways in which a DNA sample for genetic screening can be obtained.
Taking tissue samples from adults or embryos produced by in vitro fertilisation.
Chorionic villus sampling or amniocentesis of embryos and fetuses in the uterus.
Genetic screening can help identify individuals who are carrying an at a gene for a particular disorder.
Genetic screening can help identify individuals who are carrying an allele at a gene locus for a particular disorder.
What is the normal role of the BRCA1 and BRCA2 genes?
They produce tumour suppressor proteins.
These play an important role in regulating cell growth.
True or False?
Faulty BRCA1 and BRCA2 alleles can be inherited from either parent.
True.
Faulty BRCA1 and BRCA2 alleles increase the risk of developing breast and ovarian cancers and can be inherited from either parent.
Give one advantage of genetic screening for an adult with a family history of BRCA1/BRCA2 mutations.
The person may decide to take preventative measures, e.g. having an elective mastectomy to reduce cancer risk.
Screening may also begin from an earlier age or take place more frequently.
How can genetic screening allow a person to reduce their chance of developing a disease?
Screening enables people to make sensible lifestyle choices.
For example, someone predisposed to cancer or heart disease may choose to eat a healthy diet and not smoke to reduce the chance of the disease developing.
Explain how genetic screening can help potential parents make reproductive decisions.
Screening enables potential parents to choose whether or not to have biological children.
They may not want to risk passing on a harmful allele.
Give one social disadvantage of genetic screening relating to insurance.
The results may lead to a higher price for life insurance.
This may be unaffordable compared with other people.
Explain what is meant by genetic discrimination as a disadvantage of screening.
Some people fear that individuals with disease-causing alleles may be unfairly treated as "inferior".
For example, parents with a high chance of passing on harmful alleles may be unfairly pressured into not having children.
Why might genetic screening negatively affect a person's mental wellbeing?
There may be nothing positive that can be done in response to the information discovered.
This can potentially leave the person depressed or scared.
Screening the broad genetic make-up of a potential child could lead to reproductive decisions such as foetuses without the desired genetics, raising the possibility of babies.
Screening the broad genetic make-up of a potential child could lead to reproductive decisions such as aborting foetuses without the desired genetics, raising the possibility of designer babies.
What is the role of a genetic counsellor?
To help individuals understand and process their genetic screening results.
They read out the results and explain what they mean.
At what two points might a person see a genetic counsellor?
Before screening – to inform an individual of the possible results.
After screening – to explain what the results mean.
State two things a genetic counsellor might discuss with a patient.
The chance of developing an inherited disease.
The chance of having a child with a certain disease.
Other examples include lifestyle changes, therapeutic treatments, termination, and financial or ethical issues.
A genetic counsellor may discuss the lifestyle changes that can be made to reduce or the risk of developing the disease.
A genetic counsellor may discuss the lifestyle changes that can be made to reduce or manage the risk of developing the disease.
Define personalised medicine.
Personalised medicine involves the development of more targeted drugs to treat a variety of human diseases.
It also includes the development of synthetic tissues.
What is meant by genomic medicine?
Genomic medicine uses information about an individual's genes to influence their clinical care.
Which project provides information used to develop genomic medicine?
Genome sequencing projects, such as the Human Genome Project (HGP).
True or False?
Personalised medicine can tailor treatment to an individual's genotype.
True.
Information about an individual's genes is used to develop more targeted treatments and to influence their clinical care.
How does genetic screening support personalised medicine through prevention?
Screening allows individuals with a high chance of developing specific diseases to be identified.
This means preventative measures or precautions can be taken.
Personalised medicine involves the development of more drugs to treat a variety of human diseases.
Personalised medicine involves the development of more targeted drugs to treat a variety of human diseases.
What are variable number tandem repeats (VNTRs)?
Short DNA sequences (e.g. GATA) that are repeated a variable number of times at a single location.
They are found in the non-coding sections of DNA.
In which regions of DNA are VNTRs found?
In the non-coding sections of DNA.
They may also be referred to as 'satellite' or 'microsatellite' DNA.
True or False?
The length of VNTRs varies between different people.
True.
The probability that two individuals would have the same length VNTRs is extremely small.
Why can VNTRs be used to identify the source of a DNA sample?
The length of VNTRs varies between individuals.
The probability that two people share the same length VNTRs is extremely small, so the pattern is effectively unique.
How can VNTRs be used to identify biological parents?
The number of VNTRs a person has is inherited.
Offspring inherit their VNTRs from their parents, so the patterns can be used to confirm parentage.
Only twins will produce an identical pattern of restriction fragments.
Only identical twins will produce an identical pattern of restriction fragments.
Where do restriction enzymes cut the DNA when analysing VNTRs?
At specific base sequences close to the VNTR regions.
Different restriction enzymes cut the DNA at different base sequences.
Explain why applying the same restriction enzymes to different people's DNA produces fragments of different lengths.
The distance between the recognition sites depends on the number of repeated sequences.
As the number of VNTRs differs between individuals, DNA fragments of different lengths are produced.
When VNTR fragments undergo electrophoresis, they produce a pattern that can be used to identify individuals.
When VNTR fragments undergo electrophoresis, they produce a distinctive pattern that can be used to identify individuals.
True or False?
VNTRs are found in the coding regions of DNA.
False.
VNTRs are found in the non-coding sections of DNA.
What is gel electrophoresis used for?
It is a technique used to separate molecules such as DNA, RNA and proteins.
Molecules are separated according to their size/mass and their net charge.
Why is DNA negatively charged?
Due to its phosphate groups.
Towards which electrode does DNA move during gel electrophoresis, and why?
DNA moves towards the anode (the positive electrode).
This is because DNA is negatively charged due to its phosphate groups.
True or False?
Smaller DNA fragments travel further through the gel than larger fragments.
True.
The tiny pores in the gel allow smaller fragments to move quickly and further, whereas larger fragments move slowly.
During gel electrophoresis, molecules are separated according to their size/mass and their net .
During gel electrophoresis, molecules are separated according to their size/mass and their net charge.
Which type of gel is used to separate DNA fragments?
An agarose gel.
Polyacrylamide gel (PAG) is used for separating proteins.
What happens when an electric current is applied to the gel?
The negatively charged DNA fragments migrate through the gel towards the positive electrode (anode).
Smaller fragments move faster and travel further, separating the DNA by size.
How are DNA samples placed into the gel before running electrophoresis?
A micropipette is used to carefully load the samples into wells at one end of the gel.
A DNA ladder/standard is loaded into the first well for comparison.
How are the separated DNA fragments made visible after electrophoresis?
DNA is transferred to a nitrocellulose membrane and denatured into single strands.
Tagged DNA probes are added, then visualised using X-ray film (radioactive label) or UV light (fluorescent dye).
Positively charged molecules move towards the (negative pole), whereas negatively charged molecules move towards the (positive pole).
Positively charged molecules move towards the cathode (negative pole), whereas negatively charged molecules move towards the anode (positive pole).
Why does gel electrophoresis usually depend on PCR?
Electrophoresis requires a large amount of sample.
PCR is needed to amplify the DNA fragments so there is enough material to analyse.
What is genetic fingerprinting (DNA profiling)?
A technique used to identify individuals or assess genetic relationships.
It analyses non-coding, variable regions of DNA, especially VNTRs.
What are the first two steps in the process of genetic fingerprinting?
DNA extraction – DNA is collected from cells (e.g. blood, saliva, hair root) and purified.
Amplification by PCR – specific VNTR regions are amplified to obtain enough material.
What is the role of restriction endonucleases in genetic fingerprinting?
They cut the DNA at specific sequences.
This generates fragments containing VNTRs.
How are the DNA fragments separated during genetic fingerprinting?
By gel electrophoresis, using an agarose gel and an electric current.
Smaller fragments travel further, creating a distinct pattern of bands.
What is the role of DNA probes in genetic fingerprinting?
The DNA is transferred to a membrane and denatured into single strands.
Probes (radioactive or fluorescent) bind to the VNTR regions, allowing the banding pattern to be visualised.
The pattern produced by gel electrophoresis represents an individual's unique genetic fingerprint.
The banding pattern produced by gel electrophoresis represents an individual's unique genetic fingerprint.
How can genetic fingerprints be used to confirm parentage?
Offspring inherit half of their VNTRs from each parent.
By comparing the banding patterns, parentage (e.g. paternity) can be confirmed.
True or False?
The probability of two unrelated people sharing the same genetic fingerprint is very low.
True.
Each person (except identical twins) has a unique genetic profile, particularly in their VNTR regions.
How is the final banding pattern visualised in genetic fingerprinting?
Using X-ray film (for radioactive probes).
Or UV light (for fluorescent probes).
How does a genetic fingerprint indicate low genetic diversity in a population?
Populations with low genetic diversity show more similar or repeated banding patterns.
Populations with high variability show many different VNTR patterns.
Offspring inherit half of their from each parent, allowing family relationships to be inferred from banding patterns.
Offspring inherit half of their VNTRs from each parent, allowing family relationships to be inferred from banding patterns.
State three fields in which genetic fingerprinting is used.
Forensic science (crime investigation).
Medical diagnosis.
Animal and plant breeding.
How is genetic fingerprinting used in forensic science to identify a suspect?
Samples of body cells or fluids (e.g. blood, saliva, hair) are taken from the crime scene or victim.
The DNA is profiled and compared to samples from suspects, the victim and control samples.
True or False?
If a suspect's DNA pattern matches DNA found at a crime scene, it provides strong evidence they were present.
True.
Conversely, a mismatch can exclude someone from suspicion.
Why is genetic fingerprinting suitable for use in forensic science?
Each person (except identical twins) has a unique DNA profile.
This is particularly true in their VNTR regions.
Give two uses of genetic fingerprinting in medical diagnosis.
Detecting genetic disorders – identifying disease-causing alleles (e.g. Huntington's, cystic fibrosis, BRCA1/BRCA2).
Carrier screening – determining if a person is a carrier of a recessive condition.
It is also used for tissue typing before organ transplantation.
DNA fingerprinting is used for tissue before organ transplantation to check compatibility.
DNA fingerprinting is used for tissue typing before organ transplantation to check compatibility.
Explain why genetic fingerprinting can be used to detect genetic disorders.
Some diseases are caused by specific mutations or patterns in the genome.
Comparing a patient's DNA to that of known affected individuals can detect the presence or absence of disease-causing alleles.
Give two uses of genetic fingerprinting in animal and plant breeding.
Ensuring selective breeding programmes are effective.
Confirming parentage or pedigree in livestock and crops.
It also helps maintain genetic diversity and reduce inbreeding.
Why is genetic fingerprinting useful in breeding programmes?
Breeders can confirm that offspring have inherited the correct genetic traits (e.g. high milk yield, disease resistance).
It also helps identify unrelated individuals to maintain genetic diversity.
Because banding patterns are inherited, genetic fingerprinting can confirm in paternity tests and determine family relationships.
Because banding patterns are inherited, genetic fingerprinting can confirm parentage in paternity tests and determine family relationships.
Other than identifying suspects, give one forensic use of DNA profiling.
Identifying bodies or body parts that are otherwise unidentifiable.
For example, remains that are too badly decomposed or damaged (e.g. after a bomb blast).
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