Chapter 8
DNA Replication and Repair
DNA Base Pairing
Free SampleFree access at this time
Erwin Chargaff’s rules on DNA equivalence paved the way for the discovery of base pairing in DNA. Chargaff’s rules state that in a…
The DNA Replication Fork
Free SampleFree access at this time
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a…
Lagging Strand Synthesis
Free SampleFree access at this time
During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading…
The Replisome
Free SampleFree access at this time
DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together…
Proofreading
Free SampleFree access at this time
Synthesis of new DNA molecules is carried out by the enzyme DNA polymerase, which adds nucleotides on the daughter strand complementary to the…
Replication in Prokaryotes
Free SampleFree access at this time
DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the…
Replication in Eukaryotes
Free SampleFree access at this time
In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity…
Telomeres and Telomerase
Free SampleFree access at this time
In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section…
Overview of DNA Repair
Free SampleFree access at this time
In order to be passed through generations, genomic DNA must be undamaged and error-free. However, every day, DNA in a cell undergoes several thousand…
Base Excision Repair
Free SampleFree access at this time
One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing…
Nucleotide Excision Repair
Free SampleFree access at this time
DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV…
Mismatch Repair
Free SampleFree access at this time
Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires…
Fixing Double-strand Breaks
Free SampleFree access at this time
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves…
Homologous Recombination
Free SampleFree access at this time
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One…
Gene Conversion
Free SampleFree access at this time
Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the…
DNA Damage can Stall the Cell Cycle
Free SampleFree access at this time
In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical…
Restarting Stalled Replication Forks
Free SampleFree access at this time
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the…
Olfactory recognition deficits are suggested to be able to serve as clinical marker to differentiate Alzheimer's disease (AD) subjects from…
The maintenance of the genome and its faithful replication is paramount for conserving genetic information. To assess high fidelity replication, we…