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Questions and Answers
What are genes?
What are genes?
Sequences of DNA that encode proteins.
What does the genome consist of?
What does the genome consist of?
All the chromosomes and other DNA found in an organism's cells.
Who discovered nucleic acid?
Who discovered nucleic acid?
Friedrich Mieschner
Protein-digesting enzymes destroyed nearly everything in a cell except the contents of the nucleus, according to Mieschner's findings.
Protein-digesting enzymes destroyed nearly everything in a cell except the contents of the nucleus, according to Mieschner's findings.
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What method did Robert Feulgen develop for staining DNA?
What method did Robert Feulgen develop for staining DNA?
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Somatic cells contain the same amount of DNA as gametes.
Somatic cells contain the same amount of DNA as gametes.
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What process did Fred Griffith demonstrate in his experiment with pneumococci?
What process did Fred Griffith demonstrate in his experiment with pneumococci?
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Griffith's research concluded that hereditary information is dependent on life.
Griffith's research concluded that hereditary information is dependent on life.
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What did Avery, MacLeod, and McCarty demonstrate?
What did Avery, MacLeod, and McCarty demonstrate?
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The Hershey and Chase experiment aimed to determine whether DNA or protein was the hereditary information.
The Hershey and Chase experiment aimed to determine whether DNA or protein was the hereditary information.
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Watson and Crick determined the structure of DNA as a single helix made up of two complementary strands of nucleotides.
Watson and Crick determined the structure of DNA as a single helix made up of two complementary strands of nucleotides.
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What were the major factors that contributed to Watson and Crick's discovery of the DNA structure?
What were the major factors that contributed to Watson and Crick's discovery of the DNA structure?
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The Watson-Crick template theory suggests that one DNA strand acts as a template for replicating a complementary strand.
The Watson-Crick template theory suggests that one DNA strand acts as a template for replicating a complementary strand.
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Who carried out DNA replication in vitro?
Who carried out DNA replication in vitro?
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What technique did Meselson and Stahl use to demonstrate that DNA replication is semiconservative?
What technique did Meselson and Stahl use to demonstrate that DNA replication is semiconservative?
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Topoisomerase functions in supertwisting of DNA, correcting 'overwinding' ahead of replication forks.
Topoisomerase functions in supertwisting of DNA, correcting 'overwinding' ahead of replication forks.
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What separates the DNA strands during replication?
What separates the DNA strands during replication?
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What prevents the separated DNA strands from rebinding?
What prevents the separated DNA strands from rebinding?
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What lays down a short complimentary strand of RNA as a primer for DNA synthesis?
What lays down a short complimentary strand of RNA as a primer for DNA synthesis?
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What is the primary DNA polymerase responsible for laying down most of the complementary DNA strands?
What is the primary DNA polymerase responsible for laying down most of the complementary DNA strands?
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What DNA polymerase lays down complimentary strands of DNA running in the 5' to 3' direction and is involved in the removal of RNA primers and repairs nicks in the lagging strand?
What DNA polymerase lays down complimentary strands of DNA running in the 5' to 3' direction and is involved in the removal of RNA primers and repairs nicks in the lagging strand?
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What enzyme seals nicks in the backbone of DNA by catalyzing a reaction between phosphates and sugars?
What enzyme seals nicks in the backbone of DNA by catalyzing a reaction between phosphates and sugars?
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DNA polymerase III functions in the 5' to 3' direction, meaning it can only add nucleotides to the existing 3' end of the strand.
DNA polymerase III functions in the 5' to 3' direction, meaning it can only add nucleotides to the existing 3' end of the strand.
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The lagging strand is synthesized continuously, just like the leading strand.
The lagging strand is synthesized continuously, just like the leading strand.
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What are the short segments of DNA synthesized on the lagging strand called?
What are the short segments of DNA synthesized on the lagging strand called?
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DNA polymerase I removes RNA primers and replaces them with DNA.
DNA polymerase I removes RNA primers and replaces them with DNA.
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DNA ligase seals nicks in the backbone of the DNA molecule via a simple, straightforward process.
DNA ligase seals nicks in the backbone of the DNA molecule via a simple, straightforward process.
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DNA polymerase has a proofreading function which eliminates any errors made during replication.
DNA polymerase has a proofreading function which eliminates any errors made during replication.
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Mismatched bases can be removed by DNA polymerase, but this doesn't affect the overall accuracy of replication.
Mismatched bases can be removed by DNA polymerase, but this doesn't affect the overall accuracy of replication.
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Nucleotide excision repair replaces an error in DNA, but it is not able to fix DNA damage caused by radiation or UV exposure.
Nucleotide excision repair replaces an error in DNA, but it is not able to fix DNA damage caused by radiation or UV exposure.
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What are thymine dimmers and how are they removed?
What are thymine dimmers and how are they removed?
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Eukaryotic DNA cannot be replicated to the 3' end of a DNA molecule because the primers can't be removed and the ends can't be replicated.
Eukaryotic DNA cannot be replicated to the 3' end of a DNA molecule because the primers can't be removed and the ends can't be replicated.
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What are telomeres and what is their function?
What are telomeres and what is their function?
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Somatic cells have an unlimited life because of the length of their telomeres.
Somatic cells have an unlimited life because of the length of their telomeres.
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Prokaryotic DNA is linear, while eukaryotic DNA is circular.
Prokaryotic DNA is linear, while eukaryotic DNA is circular.
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Eukaryotic DNA replication is faster than prokaryotic DNA replication.
Eukaryotic DNA replication is faster than prokaryotic DNA replication.
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Eukaryotic DNA replication begins at multiple points on the chromosome because there is so much DNA and the process is relatively slow.
Eukaryotic DNA replication begins at multiple points on the chromosome because there is so much DNA and the process is relatively slow.
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Prokaryotes and eukaryotes have the same method for segregating newly replicated DNA molecules into daughter cells.
Prokaryotes and eukaryotes have the same method for segregating newly replicated DNA molecules into daughter cells.
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Eukaryotic segregation of DNA is more complex than prokaryotic segregation because eukaryotic cells contain a larger number of chromosomes and more genes.
Eukaryotic segregation of DNA is more complex than prokaryotic segregation because eukaryotic cells contain a larger number of chromosomes and more genes.
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Prokaryotes have true sexual reproduction.
Prokaryotes have true sexual reproduction.
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Eukaryotic cells contain two forms of each gene, called alleles, which must be segregated during gametogenesis to produce gametes for sexual reproduction.
Eukaryotic cells contain two forms of each gene, called alleles, which must be segregated during gametogenesis to produce gametes for sexual reproduction.
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Replication in organelles like mitochondria and chloroplasts is similar to prokaryotic replication because the DNA is circular and there are no histone proteins.
Replication in organelles like mitochondria and chloroplasts is similar to prokaryotic replication because the DNA is circular and there are no histone proteins.
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Organelles are completely self-sufficient and do not rely on the nucleus for any genetic information.
Organelles are completely self-sufficient and do not rely on the nucleus for any genetic information.
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Prokaryotic chromosomes are 1000 times smaller than eukaryotic chromosomes.
Prokaryotic chromosomes are 1000 times smaller than eukaryotic chromosomes.
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Eukaryotic chromosomes are single linear DNA molecules associated with some basic proteins.
Eukaryotic chromosomes are single linear DNA molecules associated with some basic proteins.
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Histones are highly basic proteins with large amounts of lysine and arginine, which are essential for binding to DNA.
Histones are highly basic proteins with large amounts of lysine and arginine, which are essential for binding to DNA.
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Two molecules each of four types of histones create a protein core around which DNA is wrapped, resulting in structures called nucleosomes.
Two molecules each of four types of histones create a protein core around which DNA is wrapped, resulting in structures called nucleosomes.
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Histone tails interact to cause the 10-nm fiber to fold/coil into 30-nm fibers.
Histone tails interact to cause the 10-nm fiber to fold/coil into 30-nm fibers.
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Looped domains coil themselves during mitosis into metaphase chromosomes; specific genes are always at specific points, ensuring a highly specific and precise process.
Looped domains coil themselves during mitosis into metaphase chromosomes; specific genes are always at specific points, ensuring a highly specific and precise process.
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What is euchromatin?
What is euchromatin?
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Study Notes
DNA as Genetic Material
- Genes are sequences of DNA encoding proteins.
- Genome encompasses all chromosomes and DNA within an organism's cells.
- Friedrich Miescher discovered nucleic acid.
- Robert Feulgen developed DNA staining methods (DNA in chromosomes).
- Fred Griffith demonstrated trait transfer between organisms.
- Avery, MacLeod, and McCarty linked DNA to transformation.
- Hershey and Chase proved DNA, not protein, is hereditary material (using radioactive isotopes).
- Watson and Crick determined DNA structure (double helix, complementary base pairs).
- Chargaff's rules (A=T, G=C) are fundamental to DNA structure.
- Rosalind Franklin's X-ray diffraction contributed crucial data.
DNA Replication and Repair
- Watson-Crick proposed a template model for DNA replication.
- Arthur Kornberg conducted the first in vitro DNA synthesis experiments.
- Meselson and Stahl demonstrated semiconservative DNA replication.
Enzymes and Proteins in DNA Replication (Prokaryotes)
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Topoisomerase alleviates DNA supercoiling.
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DNA helicase unwinds the DNA double helix.
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Single-strand binding proteins prevent strand reannealing.
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Primase synthesizes RNA primers.
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DNA polymerase III is the primary replication enzyme (5' to 3').
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DNA polymerase I removes RNA primers and replaces them with DNA.
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DNA ligase joins Okazaki fragments (lagging strand).
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DNA replication proceeds in a 5' to 3' direction on both strands.
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The leading strand is synthesized continuously, while the lagging strand is synthesized discontinuously as Okazaki fragments.
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Proofreading functions reduce errors during replication (mismatch repair).
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Other repair mechanisms exist for fixing errors (e.g., nucleotide excision repair).
Eukaryotic DNA Replication
- Eukaryotic replication is more complex than prokaryotic replication due to the linear nature of chromosomes and multiple origins of replication.
- Histone proteins package eukaryotic DNA.
Chromosomes Structure
- Prokaryotic chromosomes are circular.
- Eukaryotic chromosomes are linear.
- DNA is wrapped around histone proteins forming nucleosomes.
- Nucleosomes condense into higher-order structures during cell division.
- Euchromatin is less condensed, transcriptionally active DNA; heterochromatin is highly condensed, inactive DNA.
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Description
This quiz covers the essential concepts of DNA as genetic material, including its discovery, structure, and replication mechanisms. Key historical experiments and theories by scientists such as Miescher, Griffith, and Watson and Crick are highlighted. Test your understanding of DNA's role in heredity and the process of replication.
