3.8.4.3 Genetic fingerprinting Flashcards
Explain the biological principles that underpin genetic fingerprinting techniques
Genetic fingerprinting is based on the fact that VNTRs vary between individuals
Describe the process of genetic fingerprinting
The DNA is extracted amplified using PCR and cut using restriction enzymes Gel electrophoresis separates DNA fragments based on size A DNA probe complementary to a specific VNTR sequence is used in hybridisation The pattern of bands produced is unique to an individual except in identical twins
Explain why scientists might use genetic fingerprinting in forensic science
DNA from a crime scene can be compared to suspects The probability of two individuals having the same genetic fingerprint is extremely low except in identical twins This increases the reliability of matching DNA to individuals
Explain why scientists might use genetic fingerprinting in medical diagnosis
Genetic fingerprinting can identify genetic disorders by detecting specific alleles associated with disease
How is genetic fingerprinting useful for organ transplants?
It is useful for identifying tissue compatibility in organ transplants to reduce the risk of rejection
Explain why scientists might use genetic fingerprinting in animal and plant breeding
Genetic fingerprinting ensures desirable traits are passed on by selecting individuals with beneficial alleles
How does genetic fingerprinting help prevent inbreeding?
It helps prevent inbreeding by identifying genetically distinct individuals
Describe how gel electrophoresis is used in genetic fingerprinting
DNA samples are cut using restriction enzymes and loaded into agarose gel A voltage is applied causing DNA fragments to move towards the positive electrode
Why do smaller DNA fragments travel further in gel electrophoresis?
Smaller fragments travel faster and further than larger ones because they encounter less resistance in the gel matrix
Explain how PCR amplifies DNA for genetic fingerprinting
PCR uses a cycle of denaturation annealing and extension to amplify DNA The DNA is heated to separate strands Primers bind to complementary sequences DNA polymerase extends the strands using free nucleotides The cycle repeats exponentially increasing DNA quantity
Explain why DNA probes are used in genetic fingerprinting
DNA probes are short single-stranded sequences that are complementary to VNTR regions They are labeled with radioactive or fluorescent markers allowing detection
How do DNA probes help in genetic fingerprinting?
Probes hybridise with target sequences making VNTRs visible for comparison in genetic fingerprinting
Explain how genetic fingerprinting can be used to determine genetic relationships
Individuals inherit VNTRs from their parents By comparing genetic fingerprints the number of matching bands can be used to establish relatedness
How does genetic fingerprinting indicate close genetic relationships?
A higher number of shared bands indicates a closer genetic relationship such as parent-offspring or siblings
