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What is semi-conservative replication?
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What is semi-conservative replication?
Semi-conservative replication is a replication process in which one strand of parental DNA is kept in each new DNA molecule.
Define the term template strand.
The template strand is the original DNA strand that provides the base sequence which acts as a guide for the creation of a complementary new strand.
True or False?
DNA replication occurs in the nucleus.
True.
DNA replication occurs in the nucleus.
What does helicase do during DNA replication?
Helicase unwinds the DNA helix and breaks hydrogen bonds between base pairs, exposing the template strands.
What does the enzyme DNA polymerase do?
DNA polymerase is the enzyme that links nucleotides together to form a new DNA strand using the template strand.
What is the significance of keeping one original DNA strand?
Keeping one original DNA strand ensures genetic continuity and accuracy between generations of cells.
What happens when cytosine is exposed on the template strand?
When cytosine is exposed on the template strand, a guanine nucleotide is added to the new strand.
Define complementary base pairing.
Complementary base pairing is the specific pairing of adenine with thymine, and cytosine with guanine, in DNA.
Name the type of bond used to join one nucleotide to the adjacent nucleotide.
Phosphodiester bonds are used to join together adjacent nucleotide bases.
What is gel electrophoresis?
Gel electrophoresis is a technique used to separate DNA, RNA, or proteins based on their size and charge.
Define the term anode in the context of gel electrophoresis.
Anode is the positive pole towards which negatively charged DNA molecules move during electrophoresis.
True or False?
Smaller DNA fragments move faster during gel electrophoresis.
True.
Smaller DNA fragments move faster and therefore further during gel electrophoresis.
What is the purpose of PCR?
The purpose of PCR is to amplify specific DNA or RNA sequences, producing large quantities for analysis.
What is the function of Taq polymerase.
Taq polymerase is an enzyme used in PCR that remains stable at high temperatures and synthesizes new DNA strands.
What happens during the denaturation stage of PCR?
During denaturation, the DNA is heated to 95°C, breaking hydrogen bonds between DNA strands, causing the double strands to separate.
What is the role of primers in PCR?
Primers bind to specific sections of DNA to initiate the synthesis of new DNA strands.
True or False?
PCR can be used to amplify RNA.
True.
PCR can be used to amplify RNA as well as DNA.
What is the role of restriction enzymes in preparing DNA for gel electrophoresis?
Restriction enzymes cut DNA into fragments before separation in gel electrophoresis.
Define the term "annealing" in PCR.
Annealing is the stage in PCR where the temperature is lowered to allow primers to bind to single-stranded DNA.
What is DNA profiling?
DNA profiling is a technique used to identify individuals based on unique patterns in their DNA.
Define VNTRs.
VNTRs (Variable Number Tandem Repeats) are short, non-coding regions of DNA that vary between individuals.
True or False?
DNA profiling can be used to identify bodies in forensic investigations.
True.
DNA profiling can be used to identify bodies in forensic investigations.
What is the role of restriction endonucleases in DNA profiling?
Restriction endonucleases cut DNA into fragments that can be separated by gel electrophoresis in DNA profiling.
Define the term "genetic fingerprint."
A genetic fingerprint is a unique pattern of DNA bands created by separating VNTR fragments during gel electrophoresis.
What must be done to DNA samples before they can be analysed in gel electrophoresis?
DNA samples must be amplified using PCR before they can be analysed in gel electrophoresis.
True or False?
In DNA profiling, any band present in the child’s profile must be present in either the mother's or father's profile.
True.
Any band in the child's profile must be present in either the mother's or father's profile.
What is the significance of fluorescent probes in DNA profiling?
Fluorescent probes bind to specific DNA sequences and make the DNA fragments visible under UV light in DNA profiling.
Define "contamination" in the context of forensic DNA profiling.
Contamination refers to the accidental introduction of foreign DNA into a sample, potentially leading to incorrect results.
What increases the reliability of DNA profiling in forensic investigations?
Increasing the number of VNTR markers being compared increases the reliability of DNA profiling in forensic investigations.
What is the directionality of DNA replication?
DNA replication must occur in the 5' to 3' direction.
How does DNA polymerase add new nucleotides?
DNA polymerase adds new nucleotides by bonding the 5' phosphate group of the incoming nucleotide to the free 3'-OH group on the growing DNA strand.
Which of the DNA strands replicates in a "continuous" way, and which is "discontinuous"?
The leading strand is made continuously, following the fork as it opens.
The lagging strand is made discontinuously, in short fragments, away from the fork.
How is the leading strand synthesised during DNA replication?
The leading strand is synthesised continuously, following the replication fork as it opens.
Define the term "Okazaki fragments".
An Okazaki fragment is a small fragment of DNA created on the lagging strand of DNA during replication, due to the discontinuous nature of replication on this strand.
How is the lagging strand synthesised during DNA replication?
The lagging strand is synthesised discontinuously, in short Okazaki fragments, away from the replication fork.
What is the role of DNA primase in DNA replication?
DNA primase generates short RNA primers on the template strands to provide an initiation point for DNA polymerase III.
What are the roles of DNA polymerase III and DNA polymerase I?
DNA polymerase III starts replication by linking nucleotides in a 5' to 3' direction, while DNA polymerase I removes the RNA primers and replaces them with DNA.
What is the role of DNA ligase in DNA replication?
DNA ligase joins the Okazaki fragments on the lagging strand by catalysing the formation of sugar-phosphate bonds.
What is the purpose of proofreading by DNA polymerase III?
Proofreading by DNA polymerase III helps reduce mistakes during DNA replication, minimising mutations that could be harmful to the new cell.