DNA Replication
Understandings:
• Nucleosomes help to supercoil the DNA.
• DNA structure suggested a mechanism for DNA replication.
• Some regions of DNA do not code for proteins but have other important functions.
Aim 6: Design models to illustrate the stages of DNA replication.
Guidance
• The regions of DNA that do not code for proteins should be limited to regulators of gene expression, introns, telomeres and genes for tRNA
• Nucleosomes help to supercoil the DNA.
• DNA structure suggested a mechanism for DNA replication.
• Some regions of DNA do not code for proteins but have other important functions.
Aim 6: Design models to illustrate the stages of DNA replication.
Guidance
• The regions of DNA that do not code for proteins should be limited to regulators of gene expression, introns, telomeres and genes for tRNA
Skill: Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA. Click to learn about the Meselson Stahl experiment. Do the quiz at the end.
DNA replication is continuous on the leading strand and discontinuous on the lagging strand.
• DNA replication is carried out by a complex system of enzymes.
The replication of DNA is semi-conservative and depends on complementary base pairing.
Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds.
DNA polymerase III links nucleotides together to form a new strand, using the pre-existing strand as a template.
DNA polymerases can only add nucleotides to the 3’ end of a primer.
Details of DNA replication differ between prokaryotes and eukaryotes. Only the prokaryotic system is expected.
• The proteins and enzymes involved in DNA replication should include helicase, DNA gyrase, single strand binding proteins, DNA primase and DNA polymerases I and III.
DNA replication made easy - with a little review thrown in:
• DNA replication is carried out by a complex system of enzymes.
The replication of DNA is semi-conservative and depends on complementary base pairing.
Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds.
DNA polymerase III links nucleotides together to form a new strand, using the pre-existing strand as a template.
DNA polymerases can only add nucleotides to the 3’ end of a primer.
Details of DNA replication differ between prokaryotes and eukaryotes. Only the prokaryotic system is expected.
• The proteins and enzymes involved in DNA replication should include helicase, DNA gyrase, single strand binding proteins, DNA primase and DNA polymerases I and III.
DNA replication made easy - with a little review thrown in:
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Application: Use of Taq DNA polymerase to produce multiple copies of DNA rapidly by the polymerase chain reaction (PCR).
How are multiple copies of DNA made?
How are multiple copies of DNA made?
Application: Use of nucleotides containing dideoxyribonucleic acid to stop DNA replication in preparation of samples for base sequencing.
Dideoxynucleotides are chain-elongating inhibitors of DNA polymerase, used in the Sanger method for DNA sequencing. They are also known as 2',3' dideoxynucleotides, and abbreviated as ddNTPs (ddGTP, ddATP, ddTTP and ddCTP).
Dideoxynucleotides are chain-elongating inhibitors of DNA polymerase, used in the Sanger method for DNA sequencing. They are also known as 2',3' dideoxynucleotides, and abbreviated as ddNTPs (ddGTP, ddATP, ddTTP and ddCTP).
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DNA gyrase, also called Topoisomerase, functions to stabilize DNA in replication.
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Application: Tandem repeats are used in DNA profiling.
A tandem repeat is a sequence of two or more DNA base pairs that is repeated in such a way that the repeats lie adjacent to each other on the chromosome. Tandem repeats are generally associated with non-coding DNA. In some instances, the number of times the DNA sequence is repeated is variable.
Theory of knowledge:
Highly repetitive sequences were once classified as “junk DNA” showing a degree of confidence that it had no role. To what extent do the labels and categories used in the pursuit of knowledge affect the knowledge we obtain?
How ethical is it to keep a database of convicted felons' DNA profiles? Can we rely on DNA fingerprints for conviction? Many ethical issues surround the use of DNA in forensic technology. investigate the article below:
A tandem repeat is a sequence of two or more DNA base pairs that is repeated in such a way that the repeats lie adjacent to each other on the chromosome. Tandem repeats are generally associated with non-coding DNA. In some instances, the number of times the DNA sequence is repeated is variable.
Theory of knowledge:
Highly repetitive sequences were once classified as “junk DNA” showing a degree of confidence that it had no role. To what extent do the labels and categories used in the pursuit of knowledge affect the knowledge we obtain?
How ethical is it to keep a database of convicted felons' DNA profiles? Can we rely on DNA fingerprints for conviction? Many ethical issues surround the use of DNA in forensic technology. investigate the article below:
