Forensics DNA Fingerprinting Quiz

Questions and Answers

What does DNA stand for?

Deoxyribose Nucleic Acid

What is DNA fingerprinting and what is it used for?

Also known as profiling, it is used to distinguish between individuals of the same species.

Who invented DNA fingerprinting?

Alec Jeffreys

How is DNA fingerprinting used in forensics? Name 5 ways.

Establishing paternity, identifying victims of war and disasters, studying biodiversity, tracking GMOs, settling immigration disputes. Signup and view all the answers

How is DNA fingerprinting used in forensics?

Linking suspects to crimes, clearing suspects, identifying victims. Signup and view all the answers

For what purpose was DNA fingerprinting originally developed?

Treating diseases, medical use. Signup and view all the answers

Name several types of biological (trace) evidence in which DNA can be found.

Saliva, semen, blood, urine, skin. Signup and view all the answers

Is DNA considered class or individual evidence?

False Signup and view all the answers

Where in a cell is DNA specifically found?

In chromosomes that are located in the nucleus. Signup and view all the answers

How many chromosomes are found in human body cells? What is the exception to this?

46 total chromosomes; the exceptions are sperm and egg cells. Signup and view all the answers

What are the full names of the four bases found in DNA?

Guanine, Cytosine, Thymine, Adenine. Signup and view all the answers

Name the complements of the four bases found in DNA.

Guanine & Cytosine; Thymine & Adenine. Signup and view all the answers

What shape is a molecule of DNA?

Double helix (ladder shape). Signup and view all the answers

What are the sides of the double helix made of?

Sugars & phosphates. Signup and view all the answers

DNA in chromosomes is called what?

Nuclear DNA. Signup and view all the answers

How is mitochondrial DNA different from nuclear DNA?

Only comes from the mother; passed to the offspring from the egg, not sperm. Signup and view all the answers

What is the total amount of DNA in a cell called?

Genome. Signup and view all the answers

How many base pairs make up the human genome?

3 billion. Signup and view all the answers

Regions of encoded DNA, with directions to build molecules are called what?

Exons. Signup and view all the answers

Regions of un-encoded DNA, that do not code for the production of molecules but are useful in forensic science, are called what?

Introns. Signup and view all the answers

Where are the variations in DNA found?

In the non-coding segment (introns). Signup and view all the answers

What are polymorphisms?

Non-coded DNA segments that contain patterns of repeated base sequences that are unique to individuals. Signup and view all the answers

How do polymorphisms appear on a DNA fingerprint?

In a pattern of bands. Signup and view all the answers

What are two types of repeating DNA sequences? How many bases does each contain?

<ol> <li>Variable Numbers of Tandem Repeats (VNTR) 9-80 bases in length. 2. Short Tandem Repeats (STR) 2-5 bases in length.</li> </ol> Signup and view all the answers

Which type of repeating DNA sequence is usually preferred in forensics? Why?

STR, because it is usually much shorter. Signup and view all the answers

What is tissue matching?

Comparing DNA evidence from a crime scene with the DNA taken from a suspect. Signup and view all the answers

What is inheritance matching?

The comparing of family members' DNA for proof of familial relations. Signup and view all the answers

What is PCR? Why is it necessary for trace evidence?

Polymerase Chain Reaction (PCR) makes thousands of copies of DNA evidence so that DNA will not be useless if destroyed by forensic testing. Signup and view all the answers

What enzyme is used in PCR?

Taq polymerase. Signup and view all the answers

What three processes are repeated many times during PCR?

Denaturation, annealing, extension. Signup and view all the answers

Describe what must be done to avoid DNA evidence contamination at a crime scene.

Wear disposable gloves, use disposable instruments for handling, avoid coughing, talking, or sneezing, don't touch face or self, keep evidence in a cool and dry environment, keep evidence out of sunlight, air dry evidence. Signup and view all the answers

How does a scientist cut DNA into fragments?

By using restriction enzymes or 'molecular scissors'. Signup and view all the answers

What size DNA fragments travel farther? (big or small)

Small. Signup and view all the answers

Does DNA move to the negative or positive end of the electrophoresis chamber?

Positive. Signup and view all the answers

What is the name and abbreviation of the USA's electronic database of DNA profiles?

(CODIS) Combined DNA Index System. Signup and view all the answers

What is the purpose of marker or standard DNA?

It contains a solution with DNA fragments of an unknown length. Signup and view all the answers

Introns make up to 98.5% of DNA, what is another name for introns?

Junk DNA. Signup and view all the answers

What is denaturation?

A PCR process in which temperature is increased to separate DNA strands. Signup and view all the answers

What is annealing?

A PCR process in which temperature is decreased to allow primers to base pair to a complementary DNA template. Signup and view all the answers

What is extension?

A PCR process in which polymerase extends primer to form nascent DNA strand. Signup and view all the answers

What are RFLPs?

Restriction fragment length polymorphisms. Signup and view all the answers

What is electrophoresis?

A process that separates RFLPs according to their length, creating a DNA fingerprint. Signup and view all the answers

Study Notes

DNA Basics

DNA stands for Deoxyribose Nucleic Acid, the molecular blueprint for living organisms.
DNA fingerprinting, also known as profiling, is used to differentiate individuals within the same species.

History and Development

DNA fingerprinting was invented by Alec Jeffreys, paving the way for forensic applications.

Forensic Applications

DNA fingerprinting is utilized in various forensic contexts, including:
- Establishing paternity and parentage
- Identifying victims of wars and disasters
- Studying biodiversity
- Tracking genetically modified organisms (GMOs)
- Settling immigration disputes
In forensics, DNA fingerprinting helps link or clear suspects and identify victims.

Biological Evidence

DNA can be extracted from various trace biological samples:
- Saliva
- Semen
- Blood
- Urine
- Skin
Individual evidence refers specifically to DNA, whereas blood is classified as class evidence.

DNA Structure

DNA is housed in chromosomes within the nucleus of cells.
Human body cells contain 46 chromosomes (23 pairs), except sperm and egg cells, which have 23 single chromosomes.

DNA Bases and Pairing

The four bases in DNA are:
- Guanine
- Cytosine
- Thymine
- Adenine
Base pairs are composed of Guanine with Cytosine and Thymine with Adenine, forming the genetic code.

Molecular Configuration

DNA has a double helix structure resembling a twisted ladder.
The sides of this helix are made up of sugar and phosphate molecules.

DNA Types

DNA located within chromosomes is referred to as nuclear DNA.
Mitochondrial DNA differs as it is inherited from the mother and comes from the egg.

Genome and Variations

The complete set of DNA in a cell is known as the human genome, which contains approximately 3 billion base pairs.
Exons are the coding regions of DNA, while introns are non-coding regions essential for forensic science.

Polymorphisms

Polymorphisms are unique DNA segments that present patterns of repeated base sequences, primarily found in introns.
They manifest on DNA fingerprints as distinct bands.

Repeating DNA Sequences

Two major types of repeating DNA sequences are:
- Variable Numbers of Tandem Repeats (VNTR) ranging from 9-80 bases in length
- Short Tandem Repeats (STR) consisting of 2-5 bases in length
STRs are preferred in forensic analysis due to their shorter lengths, allowing for more efficient testing.

DNA Analysis Techniques

Tissue matching involves comparing DNA from a crime scene with a suspect's DNA.
Inheritance matching evaluates familial DNA for confirming relationships.
Polymerase Chain Reaction (PCR) amplifies small samples of DNA, making them usable for forensic examination.
PCR involves three critical processes: denaturation, annealing, and extension.

Evidence Handling

To prevent contamination of DNA evidence at crime scenes:
- Wear disposable gloves and use single-use instruments.
- Avoid speaking or touching the face and ensure evidence is stored in dry, cool conditions.

DNA Fragment Analysis

Restriction enzymes cut DNA into fragments; smaller fragments travel further during electrophoresis towards the positive end.
RFLPs (Restriction Fragment Length Polymorphisms) are the fragments produced after enzymatic cutting.

Databases and Terms

CODIS (Combined DNA Index System) is the U.S. electronic database for DNA profiles.
Junk DNA is another term for introns, comprising 98.5% of DNA but lacking coding function.

PCR Processes

Denaturation: The heating of DNA to separate strands.
Annealing: Cooling the mixture to allow primers to bond with DNA.
Extension: The process of synthesizing new DNA strands from the primers.

Overall Significance

DNA fingerprinting and analysis are crucial in modern forensics, medicine, and understanding genetic relationships.

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Description

Test your knowledge on DNA fingerprinting with this engaging quiz. From its definition to its applications in forensics, you'll learn vital information about this essential forensic tool. Challenge yourself and expand your understanding of DNA profiling!