Podcast
Questions and Answers
What is the orientation of the two polynucleotide chains in the DNA double helix?
What is the orientation of the two polynucleotide chains in the DNA double helix?
Which pair of nucleotides is correctly matched with its complement?
Which pair of nucleotides is correctly matched with its complement?
Which chemical group is found at the 5' end of a single polynucleotide strand?
Which chemical group is found at the 5' end of a single polynucleotide strand?
What is the diameter of the DNA double helix?
What is the diameter of the DNA double helix?
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How many base pairs are present in one complete turn of the DNA helix?
How many base pairs are present in one complete turn of the DNA helix?
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What is the primary conclusion of the Meselson Stahl experiment?
What is the primary conclusion of the Meselson Stahl experiment?
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In which type of replication does DNA synthesis occur bidirectionally?
In which type of replication does DNA synthesis occur bidirectionally?
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Which bases in DNA are classified as purines?
Which bases in DNA are classified as purines?
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What is the role of the nuclease in rolling circle replication?
What is the role of the nuclease in rolling circle replication?
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What structure is formed as parental strands separate during replication?
What structure is formed as parental strands separate during replication?
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How does the replication of linear DNA in eukaryotic chromosomes compare to bacterial DNA replication?
How does the replication of linear DNA in eukaryotic chromosomes compare to bacterial DNA replication?
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What is the purpose of the CsCl solution in the Meselson Stahl experiment?
What is the purpose of the CsCl solution in the Meselson Stahl experiment?
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Which statement accurately describes one characteristic of theta replication?
Which statement accurately describes one characteristic of theta replication?
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What is the primary function of dideoxyribose in the dideoxy sequencing method?
What is the primary function of dideoxyribose in the dideoxy sequencing method?
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During the dideoxy sequencing process, how is the sequence determined?
During the dideoxy sequencing process, how is the sequence determined?
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What color fluorescent dye corresponds to Guanine in the dideoxy sequencing method?
What color fluorescent dye corresponds to Guanine in the dideoxy sequencing method?
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Which step of PCR occurs at a temperature of approximately 72°C?
Which step of PCR occurs at a temperature of approximately 72°C?
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How many times are the three steps of PCR typically repeated?
How many times are the three steps of PCR typically repeated?
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What is the primary function of helicase during DNA replication?
What is the primary function of helicase during DNA replication?
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What role does the single-strand binding protein (SSB) play in DNA replication?
What role does the single-strand binding protein (SSB) play in DNA replication?
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Which protein is responsible for introducing a double-stranded break ahead of the replication fork?
Which protein is responsible for introducing a double-stranded break ahead of the replication fork?
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How does multiple initiation of replication help the process?
How does multiple initiation of replication help the process?
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What is the approximate distance between origins of replication in eukaryotic chromosomes?
What is the approximate distance between origins of replication in eukaryotic chromosomes?
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What is the typical duration for chromosomal DNA replication in eukaryotes?
What is the typical duration for chromosomal DNA replication in eukaryotes?
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What is the function of gyrase (topoisomerase II) in DNA replication?
What is the function of gyrase (topoisomerase II) in DNA replication?
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Which statement is true about the process of DNA replication timing in eukaryotes?
Which statement is true about the process of DNA replication timing in eukaryotes?
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What does the C-value represent in relation to genetic material?
What does the C-value represent in relation to genetic material?
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Which base pairs in DNA are classified as purines?
Which base pairs in DNA are classified as purines?
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How are nucleotides in a DNA strand connected?
How are nucleotides in a DNA strand connected?
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The C-value paradox highlights that genome size does not always correlate with what?
The C-value paradox highlights that genome size does not always correlate with what?
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Which of the following is NOT a component of nucleotides?
Which of the following is NOT a component of nucleotides?
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What is commonly used to refer to one complete haploid set of chromosomes?
What is commonly used to refer to one complete haploid set of chromosomes?
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What structural feature defines a polynucleotide chain in DNA?
What structural feature defines a polynucleotide chain in DNA?
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The genetic complement of a cell is known as what?
The genetic complement of a cell is known as what?
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Study Notes
Genome size
- Genome: the complete set of genetic material in an organism
- C-value: the amount of DNA in a haploid genome
- C-value Paradox: there is no relationship between genome size and organism complexity
- Genome size differences are significant across different types of organisms. For example, genome sizes among protozoa differ by 5800-fold, arthropods by 250-fold, fish by 350-fold, algae by 5000-fold, and angiosperms by 1000-fold.
DNA Structure
- DNA is a polymer of four deoxyribonucleotides
- deoxyribose (a five-carbon sugar)
- phosphoric acid
- nitrogen-containing bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)
- The nucleotides are joined by phosphodiester bonds to form a polynucleotide chain.
- Phosphate is attached to the 5' carbon of one sugar and linked to the hydroxyl group attached to the 3' carbon of the next sugar in line.
- DNA is a right-handed helix with two polynucleotide chains twisted around one another.
- Adenine pairs with Thymine.
- Guanine pairs with Cytosine.
- The strands are antiparallel.
- The backbone of each strand consists of alternating deoxyribose sugars and phosphate groups
- DNA molecule diameter: 20 Angstroms
- Each turn of the helix contains 10 bases and is 34 Angstroms long.
Replication
- Types of Replication: Theta, Rolling Circle, and Multiple initiation
- Theta Replication (bacterial)
- Can be unidirectional or bidirectional
- Rolling Circle Replication
- Common in bacteria and some eukaryotic viruses
- Multiple Initiation
- Common in eukaryotic cells
- Bidirectional.
- Replication of Chromosomal DNA in Eukaryotes
- Replication is initiated at many sites along the DNA
- Origins of replication are about 40,000 bp apart
- Replication typically takes from 5 to 10 hours.
- Semiconservative replication: Each new DNA molecule contains one original strand and one newly synthesized strand.
- Meselson-Stahl Experiment: Experiment that proved semi-conservative replication
Replication Mechanism
- 3 proteins help initiate replication:
- Helicase: unwinds DNA at the replication fork
- Single-strand binding protein (SSB): stabilizes single strands of DNA at the replication fork
- Gyrase (topoisomerase II): introduces a double-stranded break ahead of the replication fork to relieve the stress of helix unwinding.
- DNA polymerase: adds nucleotides to the 3' end of a growing DNA strand.
Telomerase
- Enzyme that extends the telomeres at the ends of chromosomes to prevent shortening during replication.
DNA manipulation
- Sanger sequencing: DNA synthesis in the presence of small amounts of fluorescently labeled nucleotides that contain the sugar dideoxyribose, which terminates DNA chain elongation
- Polymerase Chain Reaction (PCR): Method used to amplify specific DNA sequences
- Denaturation: DNA is heated to separate the strands.
- Reannealing: Primers anneal to the single-stranded DNA template.
- Elongation: DNA polymerase extends the primers, copying the DNA template.
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Description
Test your knowledge on genome sizes and the structure of DNA. This quiz covers important concepts, including the C-value paradox and the components of DNA. Understanding these fundamentals is essential for studying genetics and genomics.
