DNA Analysis Techniques Quiz

Restriction enzymes are specialized enzymes that cut DNA at specific sequences, recognizing unique patterns within the DNA molecule.

VNTRs, or Variable Number Tandem Repeats, are regions of DNA where short sequences repeat a variable number of times. These repeats are located between the restriction enzyme recognition sites.

Gel electrophoresis is a technique used to separate DNA fragments based on their size. Smaller fragments move faster through the gel, while larger fragments move slower.

Southern blotting transfers the separated DNA fragments from the gel onto a membrane, immobilizing them for further analysis. This allows for the specific detection of VNTR fragments.

A labeled DNA probe, complementary to the VNTR sequence, is introduced to the membrane. This probe specifically binds to the VNTR fragments due to sequence complementarity, allowing for their identification.

Visualization of the labeled probes reveals the VNTR-containing fragments as bands on the final output. This allows for the comparison of DNA profiles between individuals.

If an individual has the same number of repeats on both chromosomes at a locus, the analysis produces one band of DNA fragments. If the number of repeats differs, two bands are produced, corresponding to the different fragment sizes.

They recognize and cleave DNA at palindromic sequences, unique to each enzyme.

They are DNA sequences that read the same forwards and backwards on opposite strands.

They defend against external threats like viruses by degrading their DNA, protecting the host DNA.

The enzyme makes two incisions, one through each sugar-phosphate backbone of the DNA molecule.

They are generated when the enzyme cuts the DNA molecule leaving unpaired bases at the end.

They are produced when a restriction enzyme cleaves DNA in a way that results in blunt, or flat ends.

A system used to name Restriction Enzymes, based on the bacteria they came from.

It utilizes a combination of bacterial genus, species, and strain to identify the enzyme's origin.

STRs are highly variable in the number of repeats among individuals, making it unlikely for two individuals to share the same STR profile by chance. This variability makes them valuable for forensic investigations and paternity testing.

The mutation rate of STRs is low, ensuring that the number of repeats remains stable across generations, making them reliable markers for population studies and ancestry tracking.

STRs are primarily located in non-coding regions of DNA, minimizing the likelihood of impacting protein function or revealing sensitive personal traits, thus addressing ethical concerns associated with investigations using genetic markers.

The number of STR loci analyzed varies depending on the jurisdiction and database standards, with 13-20 loci commonly used for forensic purposes.

Multilocus genotypes derived from analyzing multiple STR loci are highly individualized, making it extremely improbable for two individuals to share the same exact genotype, except in the case of identical twins.

Reliable population statistics have been developed for the various alleles (versions) of each STR locus, enabling the calculation of probabilities for finding a match between a suspect's DNA and evidence.

STR typing involves comparing the DNA profile of crime scene evidence to that of a potential suspect, looking for a match. The analysis helps in identifying individuals involved in criminal investigations.

The FBI has historically used a threshold of 1 in 300 billion for a DNA match to be considered 'significant,' based on the estimated population of the United States. This threshold reflects the extremely low probability of a random match based on STR analysis.

Analyzing more STR loci increases the discriminatory power of the DNA profile, making it even less likely for two individuals to share the same profile by chance, further enhancing the reliability of forensic investigations.

A protein complex found on chromosome 6 that plays a role in the immune system by presenting antigens to T cells and triggering an immune response.

Circular DNA molecule found in mitochondria, responsible for energy production within cells.

High mutation rate in the non-coding region of mtDNA, particularly in HVR1 and HVR2.

A variation in a single DNA nucleotide at a specific location in the genome.

mtDNA analysis technique focusing on the complete base pair sequence of hypervariable regions, beyond length polymorphism.

The polymerase chain reaction (PCR) is a technique used to amplify DNA fragments, creating millions of copies from a single template.

Deoxyribonucleic acid (DNA) is a molecule found in nearly all cells, carrying genetic information. It's present in both the nucleus and mitochondria, except in red blood cells which lack both.

The PCR process involves three steps: denaturation, annealing, and extension. Denaturation separates DNA strands, annealing attaches primers, and extension replicates DNA.

A thermal cycler is a tool that precisely controls temperature changes for the PCR process, ensuring the optimal conditions for each step.

Variable loci are regions of DNA where individuals exhibit variations in their genetic sequence. These are crucial for forensic analysis.

Polymorphic loci are another name for variable loci, highlighting their diverse genetic makeup across populations.

DQA1, initially known as DQα, was the first marker used in forensic analysis for DNA typing. It was the starting point in the development of DNA profiling.

Y-STR markers are specific to the Y chromosome, making them helpful in paternity testing and tracing male lineages.

The ABO blood group system demonstrates variability with different blood types (A, B, O, AB) occurring in varying frequencies within populations.

Each individual receives one allele from their mother and one from their father at each locus. This allows for the identification of paternal and maternal contributions to a child's genetic makeup.