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Questions and Answers
What are the four nitrogenous bases found in DNA?
What are the four nitrogenous bases found in DNA?
What type of bond connects the sugar and phosphate residues in DNA?
What type of bond connects the sugar and phosphate residues in DNA?
What is the name of the five-carbon sugar found in DNA?
What is the name of the five-carbon sugar found in DNA?
How many hydrogen bonds form between a guanine (G) and a cytosine (C) base pair?
How many hydrogen bonds form between a guanine (G) and a cytosine (C) base pair?
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Which of the following statements about DNA structure is FALSE?
Which of the following statements about DNA structure is FALSE?
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What term describes the relationship between the nitrogenous bases of the two strands of DNA?
What term describes the relationship between the nitrogenous bases of the two strands of DNA?
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Why are G-C bonds stronger than A-T bonds?
Why are G-C bonds stronger than A-T bonds?
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What is the primary function of DNA in living organisms?
What is the primary function of DNA in living organisms?
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What is the primary goal of DNA isolation?
What is the primary goal of DNA isolation?
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Which of the following is NOT a factor influencing the choice of DNA isolation method?
Which of the following is NOT a factor influencing the choice of DNA isolation method?
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Why is EDTA used when collecting blood for DNA isolation?
Why is EDTA used when collecting blood for DNA isolation?
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In addition to peripheral blood, DNA can also be isolated from which of the following human materials?
In addition to peripheral blood, DNA can also be isolated from which of the following human materials?
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What is the purpose of the 'cell disintegration and lysis' stage of DNA isolation?
What is the purpose of the 'cell disintegration and lysis' stage of DNA isolation?
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Which of these is NOT a typical stage in the DNA isolation process?
Which of these is NOT a typical stage in the DNA isolation process?
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Why is it important to remove low-molecular-weight impurities during DNA isolation?
Why is it important to remove low-molecular-weight impurities during DNA isolation?
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What is the main purpose of the concentration stage of DNA isolation?
What is the main purpose of the concentration stage of DNA isolation?
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What is the purpose of adding Proteinase K in step 2?
What is the purpose of adding Proteinase K in step 2?
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What is the role of Sol S buffer in step 3?
What is the role of Sol S buffer in step 3?
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Why is the tube incubated at 70°C in step 4?
Why is the tube incubated at 70°C in step 4?
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What is the purpose of centrifuging the tube with the swab in step 6?
What is the purpose of centrifuging the tube with the swab in step 6?
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What is the main purpose of adding ethanol in step 5?
What is the main purpose of adding ethanol in step 5?
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Why is the spin-column transferred to a new collection tube in step 14?
Why is the spin-column transferred to a new collection tube in step 14?
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What does the purity ratio 260/280nm indicate?
What does the purity ratio 260/280nm indicate?
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What is the expected yield of DNA isolation in this procedure?
What is the expected yield of DNA isolation in this procedure?
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What is the purpose of the activation buffer (Buffer S) in the GeneMATRIX Swab-Extract DNA Purification Kit?
What is the purpose of the activation buffer (Buffer S) in the GeneMATRIX Swab-Extract DNA Purification Kit?
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Why is it important to avoid eating, drinking, smoking, or brushing teeth 1-2 hours before collecting cheek epithelial cells?
Why is it important to avoid eating, drinking, smoking, or brushing teeth 1-2 hours before collecting cheek epithelial cells?
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What is the recommended time for rubbing the cotton swab against the inner cheeks for optimal cell collection?
What is the recommended time for rubbing the cotton swab against the inner cheeks for optimal cell collection?
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Why is it important to use a different side of the cotton swab for each cheek?
Why is it important to use a different side of the cotton swab for each cheek?
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What is the role of the laboratory centrifuge in the DNA isolation procedure?
What is the role of the laboratory centrifuge in the DNA isolation procedure?
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What is the likely purpose of using a spectrophotometer in the DNA isolation procedure?
What is the likely purpose of using a spectrophotometer in the DNA isolation procedure?
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What is the purpose of the thermal block in the DNA isolation procedure?
What is the purpose of the thermal block in the DNA isolation procedure?
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What is the primary function of the swab stick in the DNA isolation procedure?
What is the primary function of the swab stick in the DNA isolation procedure?
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What is the typical A260/A280 ratio for pure, double-stranded DNA?
What is the typical A260/A280 ratio for pure, double-stranded DNA?
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What does an A260/A280 ratio below 1.8 indicate?
What does an A260/A280 ratio below 1.8 indicate?
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What is the primary purpose of using a spectrophotometer in DNA analysis?
What is the primary purpose of using a spectrophotometer in DNA analysis?
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Which of these is NOT a method for DNA isolation?
Which of these is NOT a method for DNA isolation?
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Which enzyme is used to degrade proteins during DNA isolation?
Which enzyme is used to degrade proteins during DNA isolation?
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What is the role of detergents like SDS and Triton-X100 in DNA isolation?
What is the role of detergents like SDS and Triton-X100 in DNA isolation?
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What is the optimal storage temperature for isolated DNA for long-term preservation?
What is the optimal storage temperature for isolated DNA for long-term preservation?
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At what wavelength does DNA absorb maximum UV light?
At what wavelength does DNA absorb maximum UV light?
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What is the primary purpose of using phenol and chloroform during DNA isolation?
What is the primary purpose of using phenol and chloroform during DNA isolation?
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What is the role of proteinase K in DNA isolation?
What is the role of proteinase K in DNA isolation?
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Which of the following is NOT a characteristic of DNA isolation using the magnetic method?
Which of the following is NOT a characteristic of DNA isolation using the magnetic method?
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In the column-based DNA isolation method, what is the purpose of the wash steps?
In the column-based DNA isolation method, what is the purpose of the wash steps?
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What is the role of buffers in DNA isolation, specifically during lysis?
What is the role of buffers in DNA isolation, specifically during lysis?
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In the initial steps of DNA isolation, why is the obtained lysate vigorously shaken in the presence of phenol and chloroform?
In the initial steps of DNA isolation, why is the obtained lysate vigorously shaken in the presence of phenol and chloroform?
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During column-based DNA isolation, what is the principle behind DNA binding to the GeneMATRIX column during centrifugation?
During column-based DNA isolation, what is the principle behind DNA binding to the GeneMATRIX column during centrifugation?
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In the magnetic method of DNA isolation, what is the role of the magnet?
In the magnetic method of DNA isolation, what is the role of the magnet?
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Study Notes
DNA Isolation and Analysis
- DNA is a linear biopolymer made of nucleotides
- Nucleotides consist of a nitrogenous base (adenine, guanine, cytosine, or thymine), a five-carbon sugar (deoxyribose), and a phosphate group
- Purines (adenine and guanine) are bicyclic, while pyrimidines (cytosine and thymine) are monocyclic
- DNA strands run antiparallel, forming a double helix
- Base pairs (G-C or A-T) are held together by hydrogen bonds (G-C has three, A-T has two)
- DNA's structure allows for replication and repair
DNA Isolation Goals and Methods
- DNA isolation is crucial for various biological studies and diagnostics (genetic diseases, cancer detection, drug development, cell therapy, and genetic engineering)
- Isolation aims to produce high-molecular-weight DNA free from proteins, other cellular components, and DNA-inhibiting enzymes
- The choice of method depends on the type of material, type of DNA desired, and sample size
- Examples of DNA isolation sources include peripheral blood, epithelial cells, fibroblast cultures, amniotic fluid cells, chorionic villi, and hair follicles
DNA Isolation Procedure
- Several fundamental stages are common to most DNA isolation procedures:
- Preliminary sample preparation (purification, fragmentation, homogenization, buffering)
- Cell disruption and DNA release (lysis)
- Purification of DNA from other cellular components
- Concentration and removal of impurities
- Evaluating DNA purity and quantity
DNA Purity and Concentration
- DNA purity is assessed by measuring absorbance at specific wavelengths using a spectrophotometer
- DNA has a maximum absorbance around 260 nm
- Protein has a maximum absorbance around 280 nm
- Ratio A260/A280 is ~1.8 for pure DNA; lower values indicate protein contamination
- DNA concentration can be calculated using the formula Cb = Cst * (Ab/Ast)
DNA Isolation Methods
- Common methods include solvent-based (phenol/chloroform) and chromatographic (silica column, magnetic beads)
Practical Part: Cheek Cell DNA Isolation
- Procedure for cheek cell swabbing and DNA isolation using a provided kit
- Equipment needed for the procedure
- Necessary safety precautions before performing the experiment (avoiding eating, drinking, smoking, and oral hygiene practices)
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Description
This quiz explores the structure and functions of DNA, including its composition of nucleotides and the significance of base pairing. It also covers the goals and methods of DNA isolation, essential for various biological applications. Test your knowledge on genetic engineering and diagnostic techniques.
