Podcast
Questions and Answers
What is the reason for the variation in the STR of siblings?
What is the reason for the variation in the STR of siblings?
How can one prove that two individuals are siblings?
How can one prove that two individuals are siblings?
Where do children receive their DNA from?
Where do children receive their DNA from?
What does STR stand for in the context of genetics?
What does STR stand for in the context of genetics?
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Which of the following statements is true about DNA comparison between siblings?
Which of the following statements is true about DNA comparison between siblings?
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What is the principle behind Gel Electrophoresis?
What is the principle behind Gel Electrophoresis?
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Which statement about RFLP is true?
Which statement about RFLP is true?
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What effect does using more probes have in RFLP analysis?
What effect does using more probes have in RFLP analysis?
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Which of the following techniques is used to visualize DNA fragments in Capillary Gel Electrophoresis?
Which of the following techniques is used to visualize DNA fragments in Capillary Gel Electrophoresis?
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What is the primary function of PCR (Polymerase Chain Reaction)?
What is the primary function of PCR (Polymerase Chain Reaction)?
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What is the typical size requirement for a DNA sample in RFLP analysis?
What is the typical size requirement for a DNA sample in RFLP analysis?
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During RFLP analysis, why are standards added for comparison?
During RFLP analysis, why are standards added for comparison?
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Which characteristic of DNA affects its migration in Gel Electrophoresis?
Which characteristic of DNA affects its migration in Gel Electrophoresis?
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What is the primary function of chromosomes in nucleated cells?
What is the primary function of chromosomes in nucleated cells?
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Which of the following statements accurately describes the composition of the human genome?
Which of the following statements accurately describes the composition of the human genome?
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In DNA profiling, what role do short tandem repeats (STRs) play?
In DNA profiling, what role do short tandem repeats (STRs) play?
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What is the relationship between the mother and father in the context of paternity and maternity testing?
What is the relationship between the mother and father in the context of paternity and maternity testing?
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What type of biological material can DNA be retrieved from at a crime scene?
What type of biological material can DNA be retrieved from at a crime scene?
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What does a perfect match between the child and alleged father indicate?
What does a perfect match between the child and alleged father indicate?
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Which statement is true regarding incomplete matches in paternity and maternity testing?
Which statement is true regarding incomplete matches in paternity and maternity testing?
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What comprises homologous chromosomes?
What comprises homologous chromosomes?
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How many pairs of chromosomes do humans typically have?
How many pairs of chromosomes do humans typically have?
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How does nature influence the genetic contribution to the child?
How does nature influence the genetic contribution to the child?
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What is the estimated weight of the DNA in one human cell?
What is the estimated weight of the DNA in one human cell?
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What is indicated by an 'alleged father' label in testing?
What is indicated by an 'alleged father' label in testing?
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What is the predominant function of non-protein coding regions of DNA?
What is the predominant function of non-protein coding regions of DNA?
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In the context of the information provided, what is essential for establishing a biological link?
In the context of the information provided, what is essential for establishing a biological link?
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What does an overlap in genetic testing suggest?
What does an overlap in genetic testing suggest?
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What implication does the term 'combined part' have in genetic testing?
What implication does the term 'combined part' have in genetic testing?
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What is the estimated age range of the skeleton found that was identified as Richard III?
What is the estimated age range of the skeleton found that was identified as Richard III?
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How many wounds were noted on Richard III's skeleton?
How many wounds were noted on Richard III's skeleton?
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What factor contributed to the curvature of Richard III's spine?
What factor contributed to the curvature of Richard III's spine?
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What type of DNA was used to establish a maternal link to Richard III?
What type of DNA was used to establish a maternal link to Richard III?
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What was the outcome for Peter Falconio, as mentioned in the passage?
What was the outcome for Peter Falconio, as mentioned in the passage?
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What significant detail is associated with Joanne Lees during the incident?
What significant detail is associated with Joanne Lees during the incident?
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Which arrest is mentioned in connection to the disappearance of Peter Falconio?
Which arrest is mentioned in connection to the disappearance of Peter Falconio?
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What was discovered at the scene related to Peter Falconio's case?
What was discovered at the scene related to Peter Falconio's case?
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At what age did Richard III die?
At what age did Richard III die?
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What condition related to Richard III is suggested to have been exaggerated in portrayals?
What condition related to Richard III is suggested to have been exaggerated in portrayals?
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What was the outcome for Colin Pitchfork after his arrest?
What was the outcome for Colin Pitchfork after his arrest?
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Which of the following statements about DNA screening is true?
Which of the following statements about DNA screening is true?
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In the case of Lesley Molseed, what was a significant issue encountered later?
In the case of Lesley Molseed, what was a significant issue encountered later?
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What event led to the realization that Ronald Castree was the murderer in the Lesley Molseed case?
What event led to the realization that Ronald Castree was the murderer in the Lesley Molseed case?
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What was a common misconception about the DNA screening of Type A individuals in the locality?
What was a common misconception about the DNA screening of Type A individuals in the locality?
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How did Ian Kelly contribute to the initial identification of Colin Pitchfork?
How did Ian Kelly contribute to the initial identification of Colin Pitchfork?
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What was the primary function of DNA databases in criminal investigations?
What was the primary function of DNA databases in criminal investigations?
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Which factor did NOT affect the investigation of Lesley Molseed's murder?
Which factor did NOT affect the investigation of Lesley Molseed's murder?
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What was a major implication of Colin Pitchfork's case for future investigations?
What was a major implication of Colin Pitchfork's case for future investigations?
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What was one result of the successful DNA match in Ronald Castree's case?
What was one result of the successful DNA match in Ronald Castree's case?
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Study Notes
DNA Structure and Function
- DNA is a polymer of nucleotides.
- Each nucleotide consists of a sugar (2-deoxyribose), a phosphate, and a base (adenine, guanine, cytosine, or thymine).
- The phosphate links the sugars.
- DNA is a double helix.
- The bases in DNA hydrogen bond to each other (A with T, and C with G).
- Human DNA has about 3 billion base pairs.
Chromosomes
- Humans have 23 pairs of chromosomes.
- 22 pairs are autosomal (non-sex chromosomes).
- 2 pairs are sex chromosomes (XX in females, XY in males).
- The Y chromosome is smaller than the X chromosome.
- Chromosomes are made of DNA wound around proteins called histones.
- Different sizes and shapes, with the largest denoted as 1.
- Pairs of chromosomes are homologous because they have the same size and same genetic structure, one from the mother and the other from the father.
- When stained with fluorescent dyes, chromosomes display distinctive bright and dark bands.
Genes
- Genes are segments of DNA that code for proteins.
- Genes range in size from 1000-10,000 base pairs.
- The number of genes varies from species to species (bacteria - several hundred to several thousand; humans - approximately 30,000).
- Non-coding regions of DNA (approximately 95% of human DNA) are called "junk DNA," but perform other roles.
The Human Genome
- The human genome is all the genetic material.
- The genome is divided into chromosomes; chromosomes contain genes, and genes are made of DNA.
- The genome contains the complete set of hereditary instructions to build, run, and maintain an organism.
DNA Profiling/Fingerprinting
- Uses 'junk' DNA (non-coding regions) due to high variability (between individuals).
- Restriction Fragment Length Polymorphism (RFLP) was used originally
- STR (Short Tandem Repeats) are repeating lengths of base pairs.
- STRs vary greatly in number of repeats between individuals and populations.
- Multiplexing analyzes multiple STRs simultaneously.
- US National database uses 13 STRs; UK uses 10 STRs.
- The probability of a match increases with the number of STRs analyzed.
PCR (Polymerase Chain Reaction)
- PCR allows a specific region of DNA to be duplicated many times (up to 1,000,000 copies).
- PCR can analyze very small amounts of DNA (e.g., 36 cells or remnants of saliva on a cigarette butt).
- PCR is useful for analyzing crime scene samples for DNA evidence.
- Each cycle takes approximately 5 minutes.
DNA Databases
- Many countries maintain DNA databases of criminals.
- DNA from a crime scene can be compared to DNA in databases.
Forensic Case Studies
- Detailed case studies included. Note successes and failures in the use of DNA databases.
- Issues arising from cold cases, and miscarriages of justice.
- The complexities of matching profiles and determining if there is sufficient evidence.
Mitochondrial DNA (mtDNA)
- A circular genome located in mitochondria.
- mtDNA contains 16,569 bases and 37 genes.
- mtDNA, unlike nuclear DNA, is inherited solely from the mother.
- mtDNA is more resistant to degradation than nuclear DNA as they occur in greater numbers.
- Variations in the D-loop region are used to distinguish individuals.
- More resistant to sample degradation than nuclear DNA and is maternally inherited, so useful in historical contexts.
Historical DNA Analysis
- Examples including analysis of the Romanovs, and issues identifying a specific individual.
- DNA evidence has been used to identify or rule out identities in historical contexts.
DNA Survival
- DNA can survive in various conditions and environments for long periods.
- DNA evidence can be found in various forms (e.g., skeletons, mummies, remains). This is important in historical contexts and forensic science where remains may be decades or even centuries old.
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Description
This quiz covers essential concepts related to DNA structure, function, and the organization of chromosomes. It explores the composition of DNA nucleotides, the chromosome pairs in humans, and the basic definition of genes. Test your understanding of these fundamental biological topics!
