Chapter 7: DNA Profile Exam 3ac

This statement is true because DNA can indeed be extracted from blood, semen, saliva, and hair follicles. These sources contain cells that have DNA, which can be isolated and extracted using various laboratory techniques. Blood is a commonly used source for DNA extraction, as it contains a high concentration of nucleated cells. Semen also contains sperm cells, which have DNA. Saliva contains cheek cells that can be used for DNA analysis. Hair follicles contain root cells that have DNA, and hair shafts can also contain trace amounts of DNA. Therefore, all of these sources can be used for DNA extraction.

Chromosomes are the correct answer because they are the long strands of DNA found in the nucleus of human cells. They carry genetic information and are responsible for the transmission of traits from one generation to another. Each human cell typically contains 46 chromosomes, except for gametes (sperm and egg cells) which have 23 chromosomes each.

Gel electrophoresis is a widely used technique in molecular biology to separate and analyze DNA fragments based on their size. In this process, DNA samples are cut into smaller fragments using restriction enzymes and then placed on a gel. An electric current is applied to the gel, causing the negatively charged DNA fragments to migrate towards the positive electrode. Since smaller fragments move faster through the gel, a distinct pattern of bands is formed, allowing scientists to determine the size and quantity of DNA fragments. Therefore, the statement that gel electrophoresis is the process where DNA is cut and placed on a gel to create a pattern based on size is true.

DNA in a gel electrophoresis separates based on its size because the gel acts as a sieve, with smaller DNA fragments being able to move more easily through the pores than larger fragments. As an electric current is applied, the negatively charged DNA molecules migrate towards the positive electrode. Smaller fragments move faster and travel further through the gel, resulting in separation based on size. This technique is commonly used in molecular biology to analyze and compare DNA samples.

Forensics examiners can compare the DNA found at a crime scene with the DNA of various suspects to determine if there is a match. If there is a match, it indicates that the suspect was present at the crime scene and therefore can be linked to the crime. This process is a crucial tool in solving crimes and identifying perpetrators.

Electrophoresis is a technique used to separate DNA molecules based on their size. In this method, the DNA samples are loaded onto an agarose gel and an electric current is applied. The negatively charged DNA molecules move towards the positive electrode, and their movement is hindered by the gel matrix. Smaller DNA fragments move faster and migrate further through the gel, while larger fragments move slower and migrate a shorter distance. This separation pattern creates a unique DNA fingerprint, which can be used for various applications such as genetic testing, forensic analysis, and paternity testing.

John's DNA matches the crime scene DNA.

An allele is the correct answer because it refers to a gene that has more than one alternating form. In the case of blood types, there are multiple alleles that code for different blood types such as A, B, and O. Alleles are different versions of the same gene found at the same location on a chromosome.

The given statement is false. In gel electrophoresis, smaller DNA fragments move faster and travel further through the gel, while larger fragments move slower and travel a shorter distance. This is because the gel matrix creates resistance, causing larger fragments to experience more hindrance and slower movement compared to smaller fragments. Therefore, the smaller size fragments actually travel the furthest in gel electrophoresis.

A restriction enzyme is a molecule that cuts a DNA molecule at a specific base sequence. It recognizes and binds to a specific DNA sequence, and then cleaves the DNA at specific points within or near that sequence. This process is important in genetic engineering and molecular biology techniques, as it allows for the manipulation and analysis of DNA. PCR (Polymerase Chain Reaction) is a technique used to amplify specific DNA sequences, STR (Short Tandem Repeat) and VNTR (Variable Number Tandem Repeat) are types of DNA sequences used in forensic analysis.

PCR stands for Polymerase Chain Reaction. It is a method used to amplify or replicate small samples of DNA into millions of copies. This technique allows scientists to create multiple copies of a specific DNA sequence, making it easier to study and analyze. PCR involves a series of temperature changes that help to denature the DNA, allowing primers to bind and DNA polymerase to synthesize new strands. This process is widely used in various fields of research, such as genetic testing, forensic analysis, and molecular biology.

A molecule labeled with a radioactive isotope that attaches to a particular sequence of DNA is known as a probe. Probes are used in molecular biology to detect and identify specific DNA sequences. They can be used to locate genes, identify genetic variations, or detect the presence of specific pathogens or mutations. By binding to the target DNA sequence, the probe allows scientists to visualize and study the DNA of interest.

A gene is a segment of DNA that contains the instructions for building a specific protein or determining a particular trait. It is the basic unit of heredity and is responsible for passing on genetic information from parents to offspring. Genes play a crucial role in determining an individual's characteristics, such as eye color, height, and susceptibility to certain diseases. They are essential for the proper functioning and development of an organism.

Gel electrophoresis is a technique used to separate DNA fragments based on their size. The fragments are loaded onto a gel and an electric current is applied, causing the fragments to move towards the positive electrode. Smaller fragments move faster and travel further, while larger fragments move slower and travel a shorter distance. This results in a pattern of bands on the gel, which can be visualized and analyzed to create a DNA fingerprint. DNA fingerprinting is a method used to identify individuals based on their unique DNA fragment patterns, making it the correct answer in this context.

STR stands for short tandem repeats, which are repeated sequences of DNA that are 2-5 base pairs in length. These repeats can vary in length and number of repetitions between individuals, making them useful for DNA profiling and forensic analysis. STR analysis involves amplifying these repeat regions using a technique called polymerase chain reaction (PCR), and the resulting DNA fragments can be used to determine an individual's unique genetic profile. Therefore, the correct answer is STR.

The given statement is incorrect. Matching DNA from a crime scene to a suspect does not automatically mean that the suspect committed the crime. While DNA evidence can be strong evidence in a case, it is not definitive proof of guilt. Other factors such as witness testimonies, alibis, and additional evidence need to be considered before concluding that a suspect is guilty. Therefore, the statement is false.

Suspect 2 left DNA at the crime scene.

The given DNA code repeats 3 times, indicating a variable number tandem repeat. Variable number tandem repeats (VNTRs) are regions of DNA where a short sequence of nucleotides is repeated a variable number of times. In this case, the sequence "GGCTCTGGATCGCTAG" is repeated three times, making it a VNTR. Short tandem repeats (STRs) are also regions of DNA with repeated sequences, but the number of repeats is usually constant. PCR (Polymerase Chain Reaction) and Gel Electrophoresis are laboratory techniques used to amplify and analyze DNA, respectively, and are not applicable in this context.

The lover is the father of the baby because the DNA analysis showed that the baby shares a band with the lover. This band was the most useful in making the decision because it indicates a genetic match between the lover and the baby, confirming paternity.